748 research outputs found
Specificity and mechanism of RNA trafficking from mouse to bacteria in the gut
No full textThe human gastrointestinal tract hosts a complex and diverse population of microorganisms collectively known as the gut microbiota. The gut microbiota plays pivotal roles in maintaining human health. Research links an imbalance in gut microbiota to several human diseases like inflammatory bowel diseases, obesity, diabetes mellitus, and gastrointestinal cancers. Consequently, modulating the gut microbiota is increasingly recognized as vital for treating these conditions, and several approaches, including probiotics, prebiotics, and faecal microbiota transplantation, are being explored for this purpose. However, strategies are lacking for precisely manipulating the composition of the gut microbiota. One emerging strategy is the use of microRNAs (miRNAs) which may be involved in the specific regulation of bacterial genes.
miRNAs are a class of small, single-stranded RNA, typically 18–25 nucleotides in length. These small RNAs primarily regulate gene expression by either facilitating the degradation of messenger RNA (mRNA) or repressing mRNA translation in mammals. Over the last 15 years, extensive literature has demonstrated the presence of miRNAs in a cell-free form including serum, saliva, urine, and faeces. Recent reports suggest that mammalian miRNAs can directly influence the composition and activity of gut bacteria by entering bacteria and interacting with bacterial genes. However, many questions remain regarding how miRNA-bacteria interactions occur under physiological conditions. This thesis aims to investigate the specificity and mechanisms underlying small RNA trafficking from mouse intestinal cells to bacteria within the gut environment.
To explore the miRNA-bacteria interactions, a crucial first step is to identify the miRNAs that are naturally transferred to the gut microbiota. We developed a purification method to isolate pure gut microbiota from mouse gut contents and sequenced small RNAs in the purified gut microbiota (PGM). Our data suggest host miRNAs are naturally present within gut microbiota and show that the miRNA composition within PGM is distinct to that found in total gut contents, implying specificity. We then employed miRNA-FISH (Fluorescence In Situ Hybridization) to visualize the presence of host miRNAs within gut bacterial cells and to detect miR-21a-5p, which is the most abundant miRNA in PGM. Moreover, co-staining experiments conducted in PGM using probes for miR-21a-5p and Lactobacillus demonstrated co-localization, suggesting the uptake of miR-21a-5p by Lactobacillus. Our work provides a promising foundation on which to discover additional interactions between miRNA and bacteria within the gut.
Next, we investigated the transport mechanism of host miRNAs into bacteria. In mammals, miRNAs usually function with an Argonaute protein and it has been observed that miRNA-Ago2 (Argonaute 2) complexes are secreted by mouse intestinal epithelial cells. We hypothesized that miRNAs move with Ago2 protein and the miRNA-Ago2 complexes regulate gene expression within the gut microbiota. To test this hypothesis, we investigated whether the mouse Ago2 protein is detectable within gut microbiota and adapted a method to identify bacterial genes directly targeted by miRNA-Ago2 complexes. The detection of Ago2 was performed in PGM using western blot analysis and immunofluorescence imaging and our results suggest that there is no consistent Ago2 signal in PGM. However, PGM does not encompass the entire spectrum of bacterial species within the mouse gut. To account for possibility that Ago2 signal could be lost in the PGM purification, we employed another method to capture Ago2 and isolate associated RNAs from the intact gut tissue: CLEAR-CLIP (covalent ligation of endogenous Argonaute-bound RNAs–Crosslinking and immunoprecipitation). We identified high-confidence bacterial targets co-purifying with Ago2 in samples obtained from different segments of the gut, suggesting the transfer of host miRNAs with Ago2 protein and their potential functional role in gut bacteria. Nevertheless, further bioinformatic analysis and experimental validation are required to confirm these as genuine targets.
In order to account for other transport methods beyond Ago2, we then investigated extracellular vesicles (EVs). These lipid-bound vesicles are secreted by cells into the extracellular space and play important roles in both intercellular and inter-organismal communication. We isolated EVs from a mouse intestinal epithelial cell line (Mode-K) and profiled the miRNAs content of Mode-K EVs. Our results show that miRNAs from the let-7 family are abundant and enriched in Mode-K EVs. To explore potential specificity in the uptake of EVs by bacteria, we conducted a comparison using fluorescently labelled EVs obtained from Mode-K cells and from the gastrointestinal parasite Heligmosomoides bakeri. We show that Salmonella Typhimurium SL1344 internalize Mode-K EVs but not parasite EVs when cultured in M9 medium and the uptake of mouse or parasite EVs is not observed in E. coli W3110. These data demonstrate specificity in the interaction between mammalian EVs and SL1344. Additionally, our data indicated that Mode-K EVs exerted a stimulatory effect on the growth of SL1344 and this growth-promoting impact is dependent on the dosage of Mode-K EVs, as higher concentrations correlated with increased growth. Co-culture experiments using Triton X-100-treated Mode-K EVs confirmed the necessity of intact EVs for the observed growth promotion in SL1344. We also show that mouse miRNAs are detected in S. Typhimurium after co-culturing with Mode-K EVs. In conclusion, Mode-K EVs have the capability to deliver RNA cargo to bacteria and affect bacterial growth. However, whether this promotion effect of Mode-K EVs on SL1344 is induced by mouse miRNAs requires further investigation.
Finally, we used a genetic reporter system (Cre-loxP system) to investigate whether Mode-K EVs can deliver functional cargo into S. Typhimurium. This technique involves the donor cells secreting EVs containing Cre mRNA, which are then internalized by the reporter cells. If the Cre mRNA is translated after internalization, Cre recombinase can remove the loxP-flanked transcription terminator, leading to the production of fluorescent molecules in the reporter cells. Our co-culture experiments of mouse Cre-expressing EVs with reporter S. Typhimurium demonstrated the functional transmission of cargo from mouse to bacteria via EVs.
In summary, this thesis demonstrates that host miRNAs are present within gut microbiota under physiological conditions and provides an approach to identify interactions between miRNA and bacteria within the gut. We also demonstrate that EVs derived from intestinal epithelial cells can act as a transport mechanism for host miRNAs into specific bacteria and impact bacteria growth. These findings enhance our understanding of the specificity and mechanism of RNA trafficking from mouse to bacteria within the gut environment which could hold promising implications for modulating the gut microbiota to treat associated diseases in the future
Systematic analysis of small RNA function in respiratory virus infection
No full textRespiratory syncytial virus (RSV) and parainfluenza virus (PIV) are among the most
common causes of respiratory infections worldwide, causing morbidity and mortality
especially in young children but also elderly or immunocompromised adults.
Infections result in hundreds of thousands of hospitalizations each year, leading also
to a significant global health and economic burden. RSV alone infects nearly all
children by the age of 2 years and is estimated to cause a higher disease burden than
influenza in the adult population. Despite intensive research, there are still no licenced
vaccines or effective treatments against RSV and PIV infections. Most antiviral
approaches to date directly target the virus, although many host factors are involved
in the viral replication cycle.
MicroRNAs (miRNAs) are a class of small regulatory RNAs that canonically supress
gene expression by binding to the 3’ untranslated region (3’ UTR) of messenger RNAs
(mRNAs). Several miRNAs have been reported to be altered upon viral infection and
these alterations can suppress or boost host immune responses and the viral infection
progress, depending on the targets of the miRNAs. However, there is no systematic
analysis of miRNA and target regulation in respiratory virus infection.
Previous
functional screening from our group using miRNA mimics and inhibitors demonstrated
that some miRNAs including miR-744 and miR-28 have antiviral properties against a
wide range of viruses. However, the targets of these miRNAs and their mechanisms
of action remain largely unknown.
This thesis focuses on the global characterisation of host miRNA regulation in RSV
and PIV-3 infections in the A549 epithelial cell line and then further investigates the
targets of key de-regulated or antiviral miRNAs in RSV infections.
Dynamic changes in miRNA expression over the time course of 96 h of RSV and PIV-3 infections were determined by small RNA sequencing. In general, RSV and PIV-3
induced similar de-regulation of miRNA levels, with miR-149 and miR-744 being
down-regulated and the miR-34/miR-449 cluster being upregulated. Other miRNAs
that we previously identified as antiviral (such as miR-28) were not differentially
expressed.
In addition, several viral small RNAs (vsRNAs) with a length of 22-30 nt were
identified in the small RNA sequencing data for both RSV and PIV-3. The RSV vsRNAs were found to be present not only inside the cell but also in cell culture
supernatant at early time points of infection. Small RNA sequencing from RSV-infected patients confirmed their presence in bronchial alveolar lavage fluid. Inhibition
of one of these RNAs (vsRNA L-1) inhibited RSV infection and replication, making
this RNA an interesting candidate for future therapeutic approaches.
To investigate the mechanism of action of deregulated and antiviral miRNAs in RSV
infection, miRNA targets were identified by immunoprecipitation of the RNA-induced
silencing complex (RISC), followed by ligation of the miRNA to its target and
sequencing of these chimeric RNAs. After initial optimisation, two protocols were
tested side by side to identify optimal conditions for the A549 cell line. A variation of
the CLEAR-CLIP (covalent ligation of endogenous Argonaute-bound RNAs–
Crosslinking and immunoprecipitation) protocol resulted in 3-6% of miRNA-target
interactions. Apart from canonical interactions with 3’ UTRs, high confidence targets
were identified in coding sequences (CDS) and regulatory regions using a new
bioinformatic approach developed by our laboratory. In general, miRNA expression
correlated with the number of target counts. However, for a subset of miRNAs that
were highly abundant, no high-confidence targets could be identified, including the
miR-449 family. These data suggest that additional mechanisms, such as RISC
association, regulate targeting of these miRNAs. In addition to the identification of
host targets, this analysis also identified bindings sites in the viral genome for host
miRNAs miR-26 and miR-27, which could represent a viral mechanism to suppress
these host miRNAs and up-regulate host gene expression.
High confidence targets were analysed in detail for a subset of lead candidate
miRNAs to identify their mechanisms of action. Target network analysis suggested
miR-26 and miR-27 as regulators of host genes important for viral processes. Too
few targets were found to perform target network analysis for miR-28 or miR-744, but
initial results confirm the Signal Peptidase Complex Subunit 3 (SPCS3) 3’ UTR as a
target for miR-28. This gene was reported to be essential in viral infections and could
explain the antiviral effect of miR-28 mimics.
In summary, this thesis provides a global overview of miRNA regulation during the
time course of respiratory virus infections and provides insight into new target
interaction of de-regulated or antiviral miRNAs during RSV infection.
Expanding our
knowledge of miRNA-mediated gene regulations in the context of infection will contribute to a better understanding of pathways that could be targeted in new
therapeutic strategies
Modulation of host intestinal epithelium by gastrointestinal nematode secreted extracellular vesicles
No full textHelminths have co-evolved alongside their hosts for millions of years and haveadapted eloquent mechanisms that allow them to reside in the host withoutcausing significant pathology, or elimination. The ability of these parasites tomanipulate their specialised host is reflected by their continued persistence asa global health concern, with ~1 billion people infected with soil transmittedhelminths (STHs). Helminth infections have long been associated with reducedallergic and autoimmune diseases leading to the hypothesis that helminthsuppress the host immune system, and this has been confirmed in both animalmodels and controlled human infection studies. Many studies have shown thatmany suppressive effects of infection on the host immune system can beattributed to helminth excreted/secreted products (ES). A small but growing listof individual molecules from helminth ES have been characterised, and themechanism of action elucidated. For example, multiple helminth species havebeen identified to secrete TGFβ mimic proteins that can bind host TGFβreceptor and induce T-regulatory (Treg) immunosuppressive cells. However,the full repertoire of helminth secreted molecules that modulate the host ishypothesised to be far from complete.
Our lab discovered the presence of extracellular vesicles (EVs) within ES fromthe mouse infective helminth Heligmosomoides polygyrus bakeri (H. bakeri).EVs are lipid bilayer enclosed nanoparticles that carry proteins, lipids andnucleic acids and are released ubiquitously by all cells and organisms studiedto date. In mammalian systems EVs provide a mechanism of communicationbetween near or distal cells. In the context of host-pathogen dynamics it isproposed that EVs could play a role in enabling parasites to condition theirenvironment during infection. There is mounting evidence of host-parasite EVmediated modulation occurrence between plants and colonising fungal cells,bacteria and mammalian host cells, and several parasites and theirmammalian hosts including several helminth species.
During H. bakeri infection host immune suppression is thought to primarilyoccur during the adult stage of infection when the parasite resides in the lumenof the duodenum in close proximity to the intestinal epithelium. The intestinalepithelium plays an integral role both in helminth detection, and in mediatingparasite clearance. Therefore, I hypothesised that adult H. bakeri EVs targetthe intestinal epithelium and directly modulate this tissue. The goal of thisthesis was to determine the role of helminth EVs in infection dynamics andhost modulation in the intestinal epithelium. I aimed to address whether H.bakeri EVs enter the intestinal epithelium, whether uptake is targeted to aspecific cell type and how these effects the function of this tissue usingintestinal organoid models.
To address these aims development and refinement of methods for high purityEV preparations and EV labelling was required in order to directly implicate H.bakeri EVs as the causative agent in host responses. In Chapter 3, I comparedvarious combinational approaches to EV isolation and improved the purity ofour EV and EV depleted HES preparations. I then assessed EV preparationsusing cryoEM which furthered our understanding of the morphology anddiversity of H bakeri secreted EVs. I trialled multiple labelling methodologiesand found a low-background labelling method that allowed high confidenceidentification of uptake for subsequent chapters. However, I later discoveredthat the majority of labelling techniques trialled had variable labelling efficiencywith low proportions of EVs labelled; this is a caveat to consider wheninterpreting results using labelled EVs.
To understand how H. bakeri EVs interact with the intestinal epithelium Ideveloped methods to grow small intestinal 2-D organoids (enteroids) whichare in vitro cultures that reconstitute the intestinal epithelium (Chapter 4). 2-Denteroids have greater cellular complexity as compared to a homogenous cellline and allow us to address the question of cell type specificity for uptake. 2-D enteroid cultures maintained cellular polarisation and differentiated into 6-7major cell types of the intestinal epithelium.
In Chapter 5, I demonstrated by using fluorescently labelled EVs that H. bakeriEVs enter organoid cells, however at a lower proportion than I see side-by-side for our cell line cultures. This led to the hypothesis that H. bakeri EVscould target specific cellular populations within the intestinal epithelium. Toidentify whether uptake of H. bakeri EVs occurs in a targeted fashion byspecific cell types I performed microscopy experiments aiming to co-localiseEVs with certain cell types. Microscopy approaches did not provide a definitiveanswer to the question of whether uptake is cell type specific. Next, I modifiedthe cellular proportion of our 2-D enteroids to identify whether this altered theproportion of EV uptake. Goblet and tuft cells are specialised cells of theepithelium that are strongly induced during helminth infection and mediatehelminth clearance; I reasoned that H. bakeri EVs may specifically enter andmodulate these cell types. Organoid cultures that were enriched in goblet andtuft cells showed no enhanced ability to take up EVs, suggesting that neithergoblet nor tuft cells are specifically targeted over other cell types; however, thisdata does not rule out that H. bakeri EVs can enter these cell types andmodulate them. Whether cell type specificity exists for the uptake of H. bakeriEVs within the intestinal epithelium remains unclear and is still an active areaof investigation.
To understand how EV treatment of 2-D enteroids altered host geneexpression in Chapter 6, I performed RNA sequencing (RNA seq) andcharacterised the transcriptional changes within 2-D enteroids to H. bakeri EVsor EV depleted ES after 24 h. Genes critical for maintenance of stem cells, cellcycle and antimicrobial defence were downregulated by H. bakeri EVs. Withinthe intestinal epithelium only a proportion of the cells are mitotic, thereforechanges in cell cycle suggest a modulation of either stem cells of Transit-amplifying (TA) cells. I also identified several changes in cell type restricted genes expressed specifically by stem cells, Paneth cells, TA cells orEnteroendocrine cells (EECs). I now hypothesise EVs specifically modify thesecell types. To define the cell type specific responses after EV or EV depletedES treatment I performed single cell RNA seq, unfortunately the quality of ourcontrol sample made interpreting these results difficult. However, these dataserve as conformation of the cellular composition of our 2-D enteroids model.
In addition, I also utilised our 2-D organoid model to perform novel co-culturedexperiments with live adult or larval stage 4 (L4) H. bakeri and performedtranscriptional analysis of the host epithelium under these conditions. Thesedata allow us to uncouple the impact of infection with whole parasites on theintestinal epithelium from any immune driven changes in the epithelium thatoccur in vivo. These data also serve as a comparison between host effectsattributed specifically to H. bakeri EVs, and changes induced by the wholeparasite.
In summary, this thesis contributes new knowledge to our understanding of H.bakeri interactions with the intestinal epithelium in the absence of host immunedriven responses and distinguishes the role of secreted H. bakeri EVs inmodulating this tissue. I determined that H. bakeri EVs enter host epithelialcells in 2-D enteroids, but whether this is specifically targeted to certainsubpopulations remains elusive. I characterised the host gene expressionchanges upon H. bakeri EV treatment in 2-D enteroids, these findings furtherour understanding as a field of which host genes and pathways are targetedby H. bakeri. In the future, this thesis along with continued research, couldhave important implications for helminth eradication. Conversely, where H.bakeri EVs suppress specific genes or pathways involved in diseases of theintestinal epithelium such as ulcerative colitis, Crohn's disease, oradenocarcinoma, they could provide novel strategies for therapeutics
Exosomes secreted by nematode parasites transfer small RNAs to mammalian cells and modulate innate immunity
No full textIn mammalian systems RNA can move between cells via vesicles. Here we demonstrate that the gastrointestinal nematode Heligmosomoides polygyrus, which infects mice, secretes vesicles containing microRNAs (miRNAs) and Y RNAs as well as a nematode Argonaute protein. These vesicles are of intestinal origin and are enriched for homologues of mammalian exosome proteins. Administration of the nematode exosomes to mice suppresses Type 2 innate responses and eosinophilia induced by the allergen Alternaria. Microarray analysis of mouse cells incubated with nematode exosomes in vitro identifies Il33r and Dusp1 as suppressed genes, and Dusp1 can be repressed by nematode miRNAs based on a reporter assay. We further identify miRNAs from the filarial nematode Litomosoides sigmodontis in the serum of infected mice, suggesting that miRNA secretion into host tissues is conserved among parasitic nematodes. These results reveal exosomes as another mechanism by which helminths manipulate their hosts and provide a mechanistic framework for RNA transfer between animal species.</p
Between chronicon and chanson: William of Tyre, the first crusade, and the art of storytelling
No full textThe Chronicon of Archbishop William of Tyre is not only a source of unparalleled significance for historians of the Latin East, it is also one that offers an important window onto historical writing in twelfth-century Christendom. Comprising over 1,000 pages of Latin text in the modern critical edition, its twenty-three books span (roughly) the period of Latin Christian involvement in the Levant and Syria from the genesis of the First Crusade in 1095 through to the mid-1180s. The text reflects an extensive writing process, one that most historians argue began c. 1170 and lasted until the period immediately preceding the author's death c. 1184/86. Unsurprisingly for such a lengthy and important work, the Chronicon and its author have attracted widespread interest. However, except for Peter Edbury and John Rowe's 1988 study, scholars have rarely taken a broad-ranging approach to the Chronicon. Instead, recent work has largely focused on examining specific elements or themes of the text, with a growing interest in William's authorial strategies mirroring the emergence of literary approaches to crusade narratives. The Chronicon's first eight books, which account for over a third of the entire work and include the author's retelling of the First Crusade, have nevertheless either been ignored, largely because they are viewed as derivative and of little value in tracing William's authorial voice or ideological standpoints, or approached only to confirm arguments regarding related texts, especially Albert of Aachen's Historia Ierosolimitana and the so-called ‘Lost Lotharingian Chronicle’.
Some recent work has begun to redress this, but a close, careful and detailed analysis of William's account of the First Crusade remains necessary, especially given Edbury and Rowe's somewhat offhand – or at least not fully explored – concluding remark that ‘only in the story of the First Crusade did [William’s] narrative achieve a genuine homogeneity’. Such a study is vital to achieving a better understanding of the author and his text, for these sections offer the best opportunity to trace William's historical method by pinpointing his use and adaptation of other sources to craft his own version of events. But re-examining William's account of the First Crusade is also valuable because it will help to situate the Chronicon more firmly within the wider flourishing of history creation during the twelfth century and beyond, in both a crusading and non-crusading context
Functional diversification of Argonautes in nematodes:an expanding universe
No full textIn the last decade, many diverse RNAi (RNA interference) pathways have been discovered that mediate gene silencing at epigenetic, transcriptional and post-transcriptional levels. The diversity of RNAi pathways is inherently linked to the evolution of Ago (Argonaute) proteins, the central protein component of RISCs (RNA-induced silencing complexes). An increasing number of diverse Agos have been identified in different species. The functions of most of these proteins are not yet known, but they are generally assumed to play roles in development, genome stability and/or protection against viruses. Recent research in the nematode Caenorhabditis elegans has expanded the breadth of RNAi functions to include transgenerational epigenetic memory and, possibly, environmental sensing. These functions are inherently linked to the production of secondary siRNAs (small interfering RNAs) that bind to members of a clade of WAGOs (worm-specific Agos). In the present article, we review briefly what is known about the evolution and function of Ago proteins in eukaryotes, including the expansion of WAGOs in nematodes. We postulate that the rapid evolution of WAGOs enables the exceptional functional plasticity of nematodes, including their capacity for parasitism
Rancang Bangun Buck Converter Efisiensi Tinggi Dengan Pengendali Arduino Nano Berbasis Simulasi Multisim 14.2
No full textA DC converter is needed to adjust the voltage generated by the PV cell so that it can be connected to the battery. DC converter devices have various efficiencies depending on the type of topology, as well as the selection of electronic components that make up the DC converter which has an impact on a lot of wasted energy in the electrical conversion process. According to Chapman (2005:105), the Buck Converter topology has an efficiency of up to 85%. A common challenge found in all types of DC converters is how to design a DC converter with high work efficiency. The author designed a Buck Converter with an efficiency of up to 90%, which can be integrated with a 20Wp PV Cell as input and a 12V50Ah VRLA Battery as output. The design begins by making a circuit simulation on the NI Multisim 14.2 software. Based on the simulation, a Buck Converter prototype was made with an Arduino Nano controller. Input Voltage Variation Test resulted that the maximum efficiency of the Buck Converter Simulation is 98% and the maximum efficiency of the Buck Converter Prototype is 92%. Duty Cycle Variation Test resulted that the maximum efficiency of Buck Converter Simulation is 99.3% and the maximum efficiency of Buck Converter Prototype is 96.4%. Load Variation Test resulted that the maximum efficiency of Buck Converter Simulation is 97.3% and the maximum efficiency of Buck Converter Prototype is 91.8%
Parasite-derived microRNAs in host serum as novel biomarkers of helminth infection
No full textBackgroundMicroRNAs (miRNAs) are a class of short non-coding RNA that play important roles in disease processes in animals and are present in a highly stable cell-free form in body fluids. Here, we examine the capacity of host and parasite miRNAs to serve as tissue or serum biomarkers of Schistosoma mansoni infection.Methods/Principal FindingsWe used Exiqon miRNA microarrays to profile miRNA expression in the livers of mice infected with S. mansoni at 7 weeks post-infection. Thirty-three mouse miRNAs were differentially expressed in infected compared to naïve mice (>2 fold change, p<0.05) including miR-199a-3p, miR-199a-5p, miR-214 and miR-21, which have previously been associated with liver fibrosis in other settings. Five of the mouse miRNAs were also significantly elevated in serum by twelve weeks post-infection. Sequencing of small RNAs from serum confirmed the presence of these miRNAs and further revealed eleven parasite-derived miRNAs that were detectable by eight weeks post infection. Analysis of host and parasite miRNA abundance by qRT-PCR was extended to serum of patients from low and high infection sites in Zimbabwe and Uganda. The host-derived miRNAs failed to distinguish uninfected from infected individuals. However, analysis of three of the parasite-derived miRNAs (miR-277, miR-3479-3p and bantam) could detect infected individuals from low and high infection intensity sites with specificity/sensitivity values of 89%/80% and 80%/90%, respectively.ConclusionsThis work identifies parasite-derived miRNAs as novel markers of S. mansoni infection in both mice and humans, with the potential to be used with existing techniques to improve S. mansoni diagnosis. In contrast, although host miRNAs are differentially expressed in the liver during infection their abundance levels in serum are variable in human patients and may be useful in cases of extreme pathology but likely hold limited value for detecting prevalence of infection
Syringogaster palenque Marshall & Buck 2009, new species
No full textSyringogaster palenque Marshall & Buck, new species Figs. 43–45; Plate 2F; Map 6 DESCRIPTION: Head uniformly pale reddish brown except for black ocellar tubercle. Frons including ocellar triangle tomentose; ocellar triangle strongly tapered and triangular, anterior apex rounded and separated from frontal margin by 2X scape length; remainder of frons tomentose and dull; ocellar triangle on same plane as rest of frons, flanked on each side by a row of 5–6 very small inclinate bristles. Ocellar bristles well developed. Pedicel almost entirely setulose, a small anteromedial area bare and shining. Face pale, lower part expanded and with black bristles; shining vibrissal angle with thin black bristles. Gena and subgena subequal in height at middle, gena with only fine pale setulae behind shining and sparsely setose vibrissal angle. Supracervical collar 2–3X length of pronotum, lateral carina continuous with prominent, anteriorly directed posterior tentorial pit. Thorax: Pronotum dark dorsally and reddish laterally, very short medially. Mesonotum mostly dark excluding reddish brown postpronotum and small anterolateral area in front of humeral carina. Humeral, notopleural and supra-alar carinae well developed, the latter very large and prominent. Pleuron mostly dark brown to black excluding reddish brown propleuron and anterior part of anepisternum, shining reddish anterior part of anepisternum well demarcated from dark and tomentose posterior part; katepisternum mostly bare and shining, tomentose along anterodorsal margin and with scattered long setulae; anepimeron dull tomentose. Metathoracic spiracle prominent and long-setose, first and second prespiracular lobes small, subspiracular ridge large and divided into a shining anterior part and a tomentose posterior part. Metasternum reddish brown, postmetacoxal bridge dark reddish brown to medium brown. Fore coxa whitish, remainder of leg pale brown except for somewhat darkened tibia; all bristles pale and thin (no stout, black anteroventral spines on femur). Mid femur whitish basally, rest of femur pale brown except for more or less developed darker dorsal streak in distal 2/3; tibia yellowish, sometimes with brown basal half. Mid tarsomeres 1–3 with antero- and posteroventral sawlines. Hind femur with a narrow, indistinct white basal ring; remainder of leg orange-brown except for dark brown concave apicoventral area and sometimes brown subbasal ring. Hind femur concave and densely tomentose dorsally on distal third, convex and glabrous for balance of dorsal surface; anteroventral row of 11–14 spines extending over distal 7/10 of femur, posterior row shorter. Hind tibia with apex weakly trilobate, lobes subequal. Sawlines present on hind tarsomeres 1–3. Wing dark with clear patches forming transverse bands before and after crossvein dm-cu and before crossvein bm-cu. Fork of CuA distal to bm-cu, separated from bm-cu by more than twice the length of bm-cu; A 1 +CuA 2 and CuA 1 each extending about half way to wing margin. R 2+3 running almost parallel to costa distally, not distinctly turned up to costa near apex. Cell r 4+5 greatly tapered from apex to level of r-m; r-m less than one third as long as dm-cu. Abdomen: Abdomen strongly petiolate, syntergite 1–3 parallel-sided on at least basal half, tergite 3 twice as wide at apex as base. Syntergite 1–3 densely microsculptured, sculpturing forming transverse ridges on tergite 1, densely tomentose. Abdomen reddish brown, dark brown along posterior margins of all tergites including each of tergites 1 and 2; no suture line between tergites 2 and 3; tergite 4 separate from tergite 3. Female terminalia: Tergite 7 with deep posteromedial emargination. Four spermathecae in two pairs, each pair close together on short ducts, touching but not fused; spermatheca smooth, broadly cylindrical, with a broad basal invagination and a small smooth, cylindrical cap (evagination) distally, cap about 0.25X spermathecal diameter. Male terminalia: Tergite 5 with ventrolateral margins unmodified, ventrolateral margin of tergite 6 with a tapered anteroventral corner; spiracles 5 and 6 in tergite close to lateral margin. Membranes of abdominal segments 4 and 5 densely covered with stout black spinules, sternite 5 divided into two small, widely separated round sclerites, each with 3 or 4 bristles on each sclerite; sternite 6 short and transverse, irregularly interrupted several times. Synsternite 7+8 with ventral part broad, right spiracle lateroventral and left spiracle lateral. Epandrium longer than wide. Cercus and surstylus narrow and elongate, cercus 3X as long as width, surstylus 4X as long as greatest width, slightly curved and gradually tapered towards apex; outer surface of surstylus with long hairs some of which are almost as long as the surstylus. Hypandrium with two pairs of breaks or weakenings: first between basal U-shaped portion and base of hypandrial arms, weakening between hypandrial bridge and mesal base of each hypandrial arm secondarily closed but still with an anterior and a posterior incision, second near middle of each hypandrial arm posterior to ventral hypandrial lobe. Anterior U-shaped portion robust, anterior apodeme hardly developed. Hypandrial bridge very broad and considerably projecting posteriorly below cerci, medial length almost as great as width. Posterior part of hypandrial arm broad, with broad, rounded ventral lobe; ventral hypandrial lobe elongate, distally long-setose. Pregonite with longitudinal dorsal, ventral and medial carinae. Basiphallus with apex moderately expanded, bearing posteriorly directed finger-like lobe on left side. Distiphallus relatively short, with a basal part made up of several plates including a large, cup-shaped left basal sclerite; distal part with a long sickle-shaped, sclerite directed medially from right side. TYPE MATERIAL: Holotype ♀ (DEBU): ECUADOR. Pichincha Prov., 47 km S Sto. Domingo, Río Palenque Biological Station, 250 m, 17–25.ii.1979, S.A. Marshall. Paratypes: COLOMBIA. Montería, iii.1958, M. R. Wheeler (1♂, badly damaged, lacking head and most legs, AMNH). ECUADOR. Guayas, Naranjal, xii.1955, Levi-Castillo (♀, head missing, USNM); Puruguay, house of Alfredo Paliz, 1°27.52’S, 79°12.33’W, 690 m, 5–7.iii.2006, secondary forest and garden, yellow pan traps around the house, M. v. Tschirnhaus, “EC1808” (1♀, DEBU). ETYMOLOGY: This species is named for the biological reserve at Río Palenque, where the senior author collected the holotype in 1979 (see above). COMMENTS: Its unusually dark thorax (especially the mostly dark mesonotum) distinguishes S. palenque from the closely related S. brunneina. Syringogaster lopesi has a similar thoracic color pattern, including the pale anterior anepisternum and dark posterior anepisternum, but this species is easily distinguished from S. palenque by the presence of fore femoral spines. The male of S. palenque is distinctive for a number of postabdominal characters including the narrow, tapered, long-setose, surstylus; extremely wide hypandrial bridge; ventral lobe of posterior part of hypandrium; slender, posteriorly directed lobe on left side of apex of basiphallus (directed posterolaterally in S. brunneina), and sickle-shaped process near apex of distiphallus. Syringogaster palenque is one of only three South American species of Syringogaster known from west of the Andes (the others are the widespread S. rufa and S. brunnea). Eight species of Syringogaster have been recorded from Ecuador east of the Andes. The male paratype of S. palenque is one of only five Syringogaster specimens we have seen from Colombia. The other specimens we have seen from Colombia, including one collected at the same time and place as the holotype of S. palenque, are all S. brunneina. It is not unusual to find different species of Syringogaster together, and we recently observed S. brunneina on the same group of leaves as S. brunnea in Costa Rica.Published as part of Marshall, S. A., Buck, M., Skevington, J. H. & Grimaldi, D., 2009, A revision of the family Syringogastridae (Diptera: Diopsoidea), pp. 1-80 in Zootaxa 1996 (1) on pages 53-5
- …
