263,331 research outputs found
Dynamics of freshwater nematodes. Abundance, biomass and diversity
No full textAbebe E, Michiels I, Traunspurger W. Dynamics of freshwater nematodes. Abundance, biomass and diversity. In: Abebe E, Traunspurger W, Andrassy I, eds. Freshwater Nematodes: Ecology and taxonomy. Wallingford: CAB International; 2006: 77
Literary analysis of Orchis militaris, a book by Ivo Michiels
No full textA 'Type-ideal novel' (een 'idealtype van roman')', is according to the Flemish writer Ivo Michiels such a novel, 'that a film which can not be filmized of brought into the concrete milieu. It's a novel that does not want to compete with consumer industry, based on abundance of information, especially in the film.' (Janssens, 5) In the thesis Literary Analysis of Orchis militaris, a book by Ivo Michiels we have analysed how does a novel look like, written by an author of such a vision. The focus ov this thesis is the literary analysis of Orchis militaris (1968), which includes both formal and thematic analysis. Moreover, I integrated this book into the literary-historical context, which indicates the connection between this book and the Flemish, Dutch and world literature - especially important was the experimental literature of 50th and 60th and the French nouveau roman. During the research I managed to define the typical features of this work, a.o. the expanding sentences, almost forming a labyrinth, not censored inner monologue, very slow time, unclear boundaries between individuals and the images, the characters, which do not have any character - the only things we knoě about them, are the situations in which the characters are, there is no perspective of future or direction of movement, in the book is..
Hoover Institute Carillon [Bourdon Bell]
No full textUna Pro Pace Sono "For peace alone do I ring"C5,000 poundsPro Pace Sono Bell. Originally located in the Belgian Pavilion at the New York World's Fair, 1939-1940, 35 bells by Michiels Foundry, enlarged to 48 bells by Eijsbouts. Dedication played by Kamiel Lefevere
An iterative method for computing the pseudospectral abscissa for a class of nonlinear eigenvalue problems.
No full textWe consider the following class of nonlinear eigenvalue problems: (Σ i=1 m Aipi(λ))v = 0, where A 1,⋯, Am are given n ×n matrices and the functions p1,⋯, pm are assumed to be entire. This does not only include polynomial eigenvalue problems but also eigenvalue problems arising from systems of delay differential equations. Our aim is to compute the ∈-pseudospectral abscissa, i.e., the supremum of the real parts of the points in the ∈-pseudospectrum, which is the complex set obtained by joining all solutions of the eigenvalue problem under perturbations {δA i} i=1 m, of norm at most ∈, of the matrices {A i} i=1 m. Under mild assumptions, guaranteeing the existence of a globally rightmost point of the ∈-pseudospectrum, we prove that it is sufficient to restrict the analysis to rank-one perturbations of the form δA i = β iuv *, where u ∈ C n and v ∈ C n with β i ∈ C for all i. Using this main-and unexpected-result we present new iterative algorithms which require only the computation of the spectral abscissa of a sequence of problems obtained by adding rank one updates to the matrices Ai. These provide lower bounds to the pseudspectral abscissa and in most cases converge to it. A detailed analysis of the convergence of the algorithms is made. Their applicability and properties are illustrated by means of the delay and polynomial eigenvalue problem
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Evolutie en mechanismen van bacteriële persistentie, een snelweg voor de evolutie van genetische resistentie
No full textPersister cells constitute a small, antibiotic-tolerant fraction in an otherwise susceptible population. These phenotypic variants are inherent in any bacterial species and are strongly involved in recurrent and chronic infections. An in-depth understanding of the molecular mechanisms underlying the generation, maintenance, and resuscitation of persister cells is still lacking, especially in clinically relevant pathogenic strains. This is largely due to the transient and rare nature of persister cells, which renders them inconvenient for analysis with standard molecular-genetic approaches. Additionally, it remains debated whether persistence is an evolved, adaptive strategy, or rather the result from accidental errors in cellular metabolism.
In a first part of this work, we used an innovative selection strategy to investigate the evolutionary adaptation of important Gram-negative and Gram-positive pathogens towards periodic treatment with high doses of aminoglycoside antibiotics. In all tested species, we rapidly observed a strong increase in persister levels. This finding could have profound clinical consequences, as selection for increased persister levels during actual infections could prohibit treatment success without involving increased MICs, and thus remain unnoticed by the treating physician. The genetic basis of the evolutionary adaptation towards high persistence was investigated using whole-genome sequencing. Our analysis revealed a number of new putative persistence determinants. However, mutational targets showed little overlap between species, presenting a significant hurdle for the development of genetic diagnostic markers for high persistence.
The second part of this thesis discusses the role of respiratory complex I, the first enzyme in the bacterial respiratory chain, in persistence. We repeatedly identified mutations in this large complex in evolved high-persistence mutants of laboratory and pathogenic E. coli strains. Remarkably, mutations only occurred in the subunits that are responsible for the generation of the proton motive force. We showed that bacteria expressing the mutated form of complex I displayed an intact electron transport chain, but impaired proton translocation, leading to cytoplasmic acidification and antibiotic tolerance.
Many pathogenic bacteria can invade the eukaryotic host cell to escape immune components. However, time-kill dynamics and persistence of intracellular bacteria in the face of antibiotic treatment are currently poorly characterised. We investigated the time-kill response of E. coli and P. aeruginosa in human monocytes after exposure to three different bactericidal antibiotics. Additionally, we found that mitomycin C, a promising anti-persister molecule, is also effective against intracellular bacteria.
In a final part, we used a combined experimental and mathematical modelling approach to address the long-standing hypothesis of persistence acting as a driver for the evolution of genetic antibiotic resistance. Our results show that persistence plays a dual role: it increases both the reservoir of viable cells and the mutation rate, two factors that jointly contribute to the emergence of genetically resistant mutants. Thus, the battle against antibiotic-resistant pathogens could benefit strongly from incorporating anti-persister strategies.
In conclusion, the results presented in this thesis yield interesting new insights into the evolutionary and mechanistic aspects of persistence, including its link with the emergence of genetic resistance. These results will potentially contribute to the development of better drugs and treatment strategies needed to successfully combat bacterial infections and limit the occurrence and spread of antibiotic resistance.status: Publishe
EDM-Research/UE-LASAA: published
No full textUnreal Engine 5.3 plugin for Large-area Spatially Aligned Anchors This project contains a plug-and-play Unreal Engine 5 plugin for Large-area Spatially Aligned Anchors (LASAA). The current version only supports Meta headsets. Other headsets can be integrated by changing the SDK and the code inside LASAA/Source/LASAA/Private/Anchor.cpp and LASAA/Source/LASAA/Public/Anchor.h. Source code for the following scientific publication: Vanherck, J., Zoomers, B., Jorissen, L., Vandebroeck, I., Joris, E., & Michiels, N. (2024). Large-Area Spatially Aligned Anchors. In L. T. De Paolis, P. Arpaia, & M. Sacco (Eds.), International Conference on Extended Reality (pp. 42–60). Cham: Springer Nature Switzerland. Abstract: Extended Reality (XR) technologies, including Virtual Reality (VR) and Augmented Reality (AR), offer immersive experiences merging digital content with the real world. Achieving precise spatial tracking over large areas is a critical challenge in XR development. This paper addresses the drift issue, caused by small errors accumulating over time leading to a discrepancy between the real and virtual worlds. Tackling this issue is crucial for co-located XR experiences where virtual and physical elements interact seamlessly. Building upon the locally accurate spatial anchors, we propose a solution that extends this accuracy to larger areas by exploiting an external, drift-corrected tracking method as a ground truth. During the preparation stage, anchors are placed inside the headset and inside the external tracking method simultaneously, yielding 3D-3D correspondences. Both anchor clouds, and thus tracking methods, are aligned using a suitable cloud registration method during the operational stage. Our method enhances user comfort and mobility by leveraging the headset's built-in tracking capabilities during the operational stage, allowing standalone functionality. Additionally, this method can be used with any XR headset that supports spatial anchors and with any drift-free external tracking method. Empirical evaluation demonstrates the system's effectiveness in aligning virtual content with the real world and expanding the accurate tracking area. In addition, the alignment is evaluated by comparing the camera poses of both tracking methods. This approach may benefit a wide range of industries and applications, including manufacturing and construction, education, and entertainment.MAX-R (Mixed Augmented and eXtended Reality media pipeline). Horizon Europe ProjectXRTwin SBO. Flanders Make (Belgium).Special Research Fund (BOF)FWO fellowship grant. Research Foundation - Flanders. awardNumber:1SHDZ24N
Chironomus blaylocki Wuelker, Martin, Kiknadze, Sublette & Michiels, 2009, sp. n.
No full text<i>Chironomus blaylocki</i> sp. n. <p> <i>Chironomus tentans</i> Fabricius, 1805; Blaylock <i>et al</i>. 1964; Blaylock 1965, 1966a, 1966b: karyotype and chromosomal polymorphism (misidentification); belongs to thummi-cytocomplex (Wuelker <i>et al</i>. 1968).</p> <p> <i>Chironomus</i> “ <i>decorus</i>. B” Martin 1979: chromosome arm F</p> <p> <i>Chironomus</i> “ <i>tentans</i> Blaylock ” Wuelker <i>et al</i>. 1989: karyotype</p> <p> <i>Chironomus</i> “ <i>tentans</i> Blaylock ” Wuelker <i>et al</i>. 1991: karyotype</p> <p> <i>Chironomus</i> species l Martin 2008: karyotype, and associated larva.</p> <p> <i>Chironomus blaylocki</i> Kiknadze <i>et al</i>. 2004: banding pattern of 5 chromosome arms (<i>nomen nudum</i>)</p> <p> <b>Type material.</b> Holotype, U.S.A., White Oak Creek, nr. Oak Ridge, Anderson Co., Tennessee, Sgc, 31.I.1964, " <i>C. tentans</i> ", slide 3, leg. BGB, in ZSM.</p> <p> <b>Other material examined.</b> We are in possession of only 10 salivary gland chromosome squashes of this species (coll. BGB), all from Tennessee, of which only one has the larval body on the same slide: White Oak Creek, 6 chromosome squashes as Holotype but various dates (VI. 1961 20.IX.1962 and I.1964), 4 with larval body (22.VI.1967) (location of 3 of these, partially measured, is now uncertain but likely in ZSM or UMN); Ten Mile Creek, nr. Knoxville, Knox Co. 2 SGCs (8.XI and 18.XII.1962); Mile 37.5, Mc Coy Branch, Clinch River, Knox Co. 2 SGCs (20.XI. and 17.XII.1962). There are a few male adults and larvae from White Oak Creek at the same date as the larval samples, but not clearly associated. The remark of Blaylock <i>et al</i>. (1964) that “7 different <i>Chironomus</i> species occur in Ten Mile Creek” is a warning against unproved association, particularly since other species, one of which has a larva similar in gross morphology to that of <i>C. blaylocki</i> (Spies <i>et al</i>. 2002), have been obtained from White Oak Creek. However, there are also some measurements of three associated larvae, and a male collected at the same place and time as these larvae. This male, while problematically associated, shows overall similarity to the adults associated by rearing of <i>C. bifurcatus</i>, whose larval material constitutes a closely related cytomorphological species pair, makes the description appropriate.</p> <p>Other species recorded from the locality would not be expected to show such similarity. However, associated reared material will be necessary to confirm the adult morphology.</p> <p> <b>Etymology.</b> Elected by J.E. Sublette as a manuscript name, after B.G. Blaylock.</p> <p> <b>Diagnostic characters.</b> This species is presently most accurately identified by the unique banding pattern of the polytene chromosomes. There are unique patterns in three of the seven chromosome arms. Most of the shared patterns (arms B, C2, E and F) are with species b (Martin 2008), which may be a subspecies of <i>C. blaylocki</i> (see Discussion). There is a shared pattern of arm C with <i>C. bifurcatus</i> and in arms E and F1 with <i>C. decorus</i> (Martin 1979) and <i>C. decorus</i> R & F (Rothfels & Fairlie 1957). Due to the presence of polymorphic sequences, only the pattern blaA1 (1a–e, 8–9, 2d–3e, 15–14, 2c–1f, 16a–d, 7–4, 13a–f, 10– 12, 3i –f, 17–19) and the characteristic arm G can be expected in all specimens.</p> <p> The presumptive adult male (see below) has genitalia (Fig. 3 c) very similar to those of <i>C. bifurcatus</i> but the superior volsella on <i>C. blaylocki</i>, while dark as <i>C. maturus</i> Johannsen, 1908 and <i>C. bifurcatus</i>, is more smoothly curved but slightly angled as in both of those species and is almost evenly tapered from the base to the tip. The phallopodeme is distinctly different from those species, resembling that of <i>Chironomus atrella</i> (Townes, 1945).</p> <p> <b>Karyotype</b> (Fig. 1)</p> <p>Chromosome arm combination AB, CD, EF, G (thummi-cytocomplex). Nucleolus subterminal in arm G, no nucleolus in the long chromosome arms. Three BRs are normally visible, two in arm G (one just distal of the nucleolus, the other near the other end of the chromosome) and one in arm B (normally near middle of the arm, but may be distal due to inversion polymorphism).</p> <p> Inversion polymorphism is known in chromosome arms B, C, D and F. Some polymorphism was described by Blaylock <i>et al</i>. (1964) using different names. The relationship to the identification used here is given in Table 1.</p> <p> This paper Blaylock <i>et al</i>. 1964 blaA1 2R</p> <p>blaB1 2L</p> <p>blaB2 2Lab blaC1 1R</p> <p>blaC2 1Ra</p> <p>blaD1 1L</p> <p>blaD2 1Lc</p> <p>blaE1 3L</p> <p>blaF1 3R</p> <p>blaF2 3Ra</p> <p>Arm A</p> <p> There is only one banding pattern known in arm A, blaA1, which can be derived from arm A of <i>Chironomus harpi</i> Sublette, 1991 (Wuelker <i>et al</i>. 1991) another member of the decorus-group, by two simple inversion steps. In3f–16, leads to a hypothetical intermediate, then In13–2c leads to blaA1. Arm A of <i>C. utahensis</i>, also in the decorus-group, is a further simple inversion step from <i>C. harpi</i> (see below).</p> <p>Arm B</p> <p> B1 with a BR in the middle of the arm, followed distally by a group of dark bands. These appear to correspond to band groups 7 and 8 respectively, in the standard system of Dévai <i>et al</i>. (1989). Blaylock <i>et al</i>. (1964) report a complex inversion in this arm, which they call 2Lab. They considered 2Lab to be composed of two independent components that were always found together. However, our interpretation of this heterozygote, here called B1.2 (Table 1), is that it is due to overlapping inversions, similar to F1.2 of <i>C. utahensis</i> (Wuelker <i>et al</i>. 1991). The limits of these inversions are shown in Fig. 1. The longer of these inversions takes the BR to near the distal end of the arm with the dark bands proximal to it (Fig. 4 a).</p> <p>Arm C</p> <p> Two banding patterns have been recorded. Although less frequent, blaC1 appears phylogenetically more basal, as it is only a simple inversion step from the common pattern recorded in a number of species of <i>Chironomus</i> (Wuelker 1991). C2 differs from C1 by a small simple inversion, 2f–6.</p> <p> There is an additional polymorphism of this chromosome, in which the centromere band is puffed. In the heterozygote the puffing may disrupt pairing in the vicinity, leading to Blaylock <i>et al</i>. (1964) describing it as an inversion (1Rb). The arm C in Fig. 1 is homozygous for the puffed band.</p> <p>Arm D</p> <p> Of the two patterns reported for this arm by Blaylock <i>et al</i>. (1964), we have only seen one. There are two equally parsimonious explanations for the derivation of the more frequent pattern D1. It can be derived from the common pattern of Wuelker (e.g. 1991) by 4 intermediate patterns involving 6 simple inversions. Note that the step from inter 3 to inter 4 in this scheme would restore group 18 to its original state, which in inter 2 is 18g –a.</p> <p> Equally, it may be derived from the pattern of <i>Chironomus piger</i> Strenzke, 1951 by a similar number of steps:</p> <p> The second sequence, D2, on the basis of the description and photograph in Blaylock <i>et al</i>. (1964), is derived from D1 by a simple inversion of about 11–19g.</p> <p>Arm E</p> <p> Only one pattern, blaE1, has been found in this arm. It differs from the basic pattern for this arm as found in <i>Chironomus aberratus</i> Keyl, 1961 (Wuelker 1980) by the simple inversion 5–8.</p> <p> The E1 pattern is also found in other decorus-group species, such as <i>C. decorus</i> (R&F) and C. species 3a (Martin <i>et al</i>. 1979), as well as in <i>C. maturus</i> (Wuelker & Martin 1974) and <i>C. stigmaterus</i> Say, 1823 (Martin & Wuelker 1974).</p> <p>Arm F</p> <p> Two patterns have been reported in arm F. The only homozygote represented in our sample is blaF2.2. This pattern differs from blaF1 by the simple inversion 5c–16, while F1 differs from the standard (basic) pattern of <i>C. piger</i> by the characteristic inversion of the decorus-group, 2–9.</p> <p> The pattern blaF1 is also found in <i>C. decorus</i> (Martin <i>et al</i>. 1979).</p> <p>Arm G</p> <p> Long, stretched, and paired, according to Blaylock <i>et al</i>. (1964), but with pairing gaps in our material. One BR near one end, a subterminal nucleolus at the other end and another BR distal of the nucleolus.</p>Published as part of <i>Wuelker, Wolfgang, Martin, Jon, Kiknadze, Iya I., Sublette, James E. & Michiels, Susanne, 2009, Chironomus blaylocki sp. n. and C. bifurcatus sp. n., North American species near the base of the decorus-group (Diptera: Chironomidae), pp. 28-46 in Zootaxa 2023</i> on pages 29-34, DOI: <a href="http://zenodo.org/record/186122">10.5281/zenodo.186122</a>
Composition and distribution of free-living aquatic nematodes: global and local perspectives
No full textTraunspurger W, Michiels IC, Abebe E. Composition and distribution of free-living aquatic nematodes: global and local perspectives. In: Abebe E, Andrassy I, Traunspurger W, eds. Freshwater Nematodes: Ecology and taxonomy. Wallingford: CAB International; 2006: 752
Chironomus bifurcatus Wuelker, Martin, Kiknadze, Sublette & Michiels, 2009, sp. n.
No full textC. bifurcatus sp. n. Chironomus species a Martin 1979 Chironomus decorus-group species 1 Butler et al. 1995 Chironomus species a Martin 2008 Type material. Holotype, CANADA: Lake Deschêne, near Ottawa, Ontario, egg mass # 1 laid 21.IX. 66, slide C0.39.2 18 M JM, in ZSM. Other material examined. Canada. Lake Deschéne, Ottawa, Carleton Co., Ontario, from egg masses, 22–23.X. 1966 (JM), 5 Sgc with larval heads; 10 imagines 1 (I with Pex, not assoc) 3 I male, 6 I female, 5 LP female. Copanspin farm, Dunrobin, Carleton Co., Ontario, 2.V and 24.X. 1966 (JM) 7 Sgc with larval heads, 2 LPI male, 1 LI female, 1 LI male, 1 P female. Edge of creek 1 / 2 mile e. Dunrobin, Carleton Co., Ontario, 25.IV. 1966 and 25.IV. 1967 (JM) 5 Sgc with larval head, 1 PI female, 1 LI male, 1 LPI female, 1 PI male. Rideau River, Carleton Co., Ontario, V–VII. 1966 (JM) 2 I male, 2 LPI male, 1 LP male 1 PI male. Bear Creek, nr. Carlsbad Springs, Carleton Co., Ontario, 19.IV. 1966 (JM) 3 Sgc with larval head. Barrel drain near Squirrel Rapids, Algonquin Park, Nipissing Co., Ontario, 29.VI. 1966 (JM) 1 LPI male. Mile 14.3, Highway 60, Algonquin Park, Nipissing Co., Ontario, 1.VI. 1966 (JM) 3 Sgc with larval head, 1 LP male. Brewery Creek, Hull, Quebec, 24.VIII. 1970 (JM & J. Mackie) 3 I male, 1 P male, 3 I female, 1 female Pex, 1 P female, 9 Pex, 44 Sgc with larval head. U.S.A. Lake Michigan, Epoufette, Michigan, from egg mass # 1 laid 21.ix. 1966, em. 17–26.x. 1966, (J.M.) 4 Sgc with larval head, 2 PI male, 1 P male, 1 I female. Anderson Lake, Clearwater Co., Minnesota, 28.III. 1993 (MGB) 35 Sgc. Turtle Lake, Becker Co., Minnesota, I. 1974, III. 1974 and 19.IX. 1974 (MGB) 39 Sgc. Adult specimens are in the collections of CNC and UMN. Etymology. From the forked appearance of arm G in many polytene chromosome squashes. Diagnostic characters. This species is presently most accurately identified by the unique banding pattern of the polytene chromosomes. There are unique patterns in all of the chromosome arms, except for arm E. In arm C, one pattern is shared with C. blaylocki, but a second unique pattern also exists. It is not possible to specify a particular diagnostic sequence because specimens may have different combinations of the polymorphic sequences, but their should be one of the species specific sequences of Arms A (bifA1, 2, 3 or 4), B (bifB 1 or 2), D (bifD 1 or 2), F (bifF 1 or 2) and the characteristic arm G. In Townes (1945), the male of this species keys to “ Tendipes ” (= Chironomus) decorus (Johannsen 1905). It can be differentiated from C. decorus by that species having paler saddle-shaped fascia on terga II–V or VI (Johannsen, 1905), and with the superior volsella longer and paler and usually slightly widened near the middle. Townes’ Fig. 136 A agrees most closely with Johannsen’s type material, while 136 B is apparently Chironomus maturus Johannsen, 1918 and 136 C is probably this new species; his Fig. 136 D is possibly Chironomus whitseli Sublette & Sublette 1974. The heavier gonostylus shown in his Fig. 136 C agrees with the males here associated with this new species. The single male tentatively associated with C. blaylocki is extremely similar but has a darker abdomen and the superior volsella is longer, more evenly tapered from the base and not as angled on the lateral margin (Fig. 3 c); the phallopodemes of the two species, C. bifurcatus and C. blaylocki, are distinct (Fig. 3 c, d). The abdominal colour pattern of C. bifurcatus (Fig. 3 b) is very similar to that of C. blaylocki (Fig. 3 a) and C. maturus (Sublette & Sublette 1974, Fig. 2); however, the heavier gonostylus and the less strongly hooked superior volsella are distinctive for this species. Material is not available to definitively separate this species in the pupal stage from other member of the maturus -group. It is readily separated from C. decorus by that species having secondary tubercles on the frontal apotome (Fig. 6 a, b). Karyotype (Fig. 4) Chromosome arm combination AB, CD, EF, G (thummi-cytocomplex). Terminal nucleolus in arm G, no nucleolus in long arms. There are normally three BRs, located in similar to positions to those of C. blaylocki. Inversion polymorphism known in chromosome arms A, B and F. Arm A There are four sequences of arm A in our samples. A 2 and A 3 differ from bifA 1, by simple inversions, while A 4 can be derived from A 3 by a further simple inversion (see below). There is a problem in the location of bands 4 ab. The incomplete appearance of group 4 in the Palaearctic decorus-group species C. obtusidens was regarded by Keyl (1961, 1962) as due to structural modification. In contrast, we see bands 4 ab transported to another site on the arm. However, this may be due to an independent origin of the arm A banding patterns of C. obtusidens and C. bifurcatus, as outlined below. It is very difficult to derive the C. bifurcatus patterns from the basic arm A pattern, e.g. in C. holomelas Keyl, 1961, but the bifA 2 pattern can be obtained via 11 simple inversions (see below). This scheme indicates that bifA 2 is derived by a separate set of inversion steps to those leading to C. obtusidens and C. blaylocki. Some of the intermediate steps may eventually be found in the arm A patterns of other uncharacterised species of the decorus-group, e.g. C. decorus R&F (Rothfels & Fairlie 1957) or C. decorus (Martin et al. 1979). Arm B B 1 with BR (group 7) in the middle of the arm, which in B 2 is transported to a more distal position. The bands distal to the BR in B 1 are not group 8, as in blaB 1 of C. blaylocki, but rather the bands proximal to the BR of blaB 1. Group 8 may be more distally located in the C. bifurcatus patterns. Arm C Two patterns are present in arm C. The common C 1 has the same sequence, and consequently the same relationship to the common pattern, as in blaC 1. The second sequence, C 2, is known only as the heterozygote, and differs from C 1 by the simple inversion 4 i– 15 The pattern of bifD 1 can be derived from the common pattern of arm D by five inversion steps. It can also be derived from the pattern of C. piger, but this requires six inversion steps. Neither mode of derivation shows any common intermediate sequence with the derivation of blaD 1. Arm F The simplest explanation for the banding pattern in arm F is that it is derived from the F 1 pattern of C. blaylocki via a hypothetical intermediate with the simple inversion 6–17. A further three break inversion of this intermediate gives the pattern of bifF 1. A second sequence, bifF 2, is known only from a single heterozygote and has approximate limits 14–19. Arm G Long and stretched, generally partly unpaired like a fork (species name), but may be completely unpaired, possibly due to inversion heterozygosity. There is a virtually terminal nucleolus at the unpaired end, with a nearby BR as in C. blaylocki, and another BR near middle of arm. There is considerable variability in the degree of puffing of the BRs with developmental stage Inversion polymorphism: In our material polymorphism occurs in arms A, B, C and D, but there is a low frequency of polymorphism for heterochromatin near the nucleolus (Fig. 5 b) and also medially (Fig. 4) in arm G. As well, there can be supernumerary chromosomes in mid-Western populations (Fig. 5 b). Arm A polymorphisms are widespread, with both A 1 and A 3 common in different populations, while A 2 is less frequent. In the largest sample, South March, Ontario, the frequencies are A 1 = 46.4 %, A 2 = 13.1 %, A 3 = 40.4 %. Both sequences of arm B are common in Ontario populations (67.6 % B 1, 32.4 % B 2 at South March), but B 2 is rare in the mid-Western samples. C 2 and D 1 occur at low frequency in both Ontario and the mid- West (both 1.2 % at South March).Published as part of Wuelker, Wolfgang, Martin, Jon, Kiknadze, Iya I., Sublette, James E. & Michiels, Susanne, 2009, Chironomus blaylocki sp. n. and C. bifurcatus sp. n., North American species near the base of the decorus-group (Diptera: Chironomidae), pp. 28-46 in Zootaxa 2023 on pages 36-40, DOI: 10.5281/zenodo.18612
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