1,720,980 research outputs found
Annotated \u3cem\u3eGirardia dorotocephala\u3c/em\u3e MA-C2 Transcriptome Sequences
No full textGirardia dorotocephala MA-C2 transcriptome sequences encoding for products with homology to annotated metazoan proteins
BLAST2GO Homolog, E-value, and GO Annotation for \u3cem\u3eGirardia dorotocephala\u3c/em\u3e MA-C2 Transcriptome Assembly
No full textExcel file listing Top BLAST2GO homolog, E-value, and GO annotation for Girardia dorotocephala MA-C2 transcriptome assembly
A Primer on Regneration
No full textThe ability to restore lost tissues and body regions, a process known as regeneration, is broadly represented in both plant and animal kingdoms (Birnbaum and Sanchez Alvarado, 2008). Despite a wide phylogenetic distribution of regeneration abilities among metazoans, cumulative studies have identified a conserved series of events that take place during regeneration of complex animal structures (King and Newmark, 2012). Immediately following amputation, an organism recognizes damage and initiates wound healing, which is followed by programmed cell death in the vicinity of tissue damage and subsequent proliferation and migration of cells that foster the development of new tissue. Finally, rearrangement of pre-existing tissue and integration with newly differentiated cells restore the function and proportionality displayed prior to damage. While these conserved processes suggest that the ability to regenerate is ancestrally common (Bely, 2010), heterogeneity exists in some basic mechanisms displayed during regeneration in different animal species. Perhaps one of the most noticeable differences is the cellular source contributing to the formation of new tissue during regeneration. Organisms such as planarians and Hydra rely on active reservoirs of somatic pluripotent stem cells abundantly distributed throughout their bodies while vertebrates rely primarily on progenitor cell activation and dedifferentiation to generate cells with limited potential that then develop specific structures. However, not all regenerative events rely on cellular replacement. Recent research has identified autonomous repair mechanisms and functional regeneration of single cells – be it neurons or ciliated protozoa. The fact that organisms can achieve regeneration through diverse cellular sources is remarkable, but can these processes and conserved molecular pathways be activated to achieve regeneration in species lacking such abilities? Analysis of these pathways will contribute to better understanding of human development and provide potential avenues for regenerative medicine
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Expression and Function of Genes Involved in Spermatogenesis in the Planarian \u3cem\u3eSchmidtea mediterranea\u3c/em\u3e
Get PDFCharacterizing the molecular events that ensure proper spermatogenesis is key for understanding illnesses of the male reproductive system
Autoregulation of GLD-2 Cytoplasmic Poly(A) Polymerase
Get PDFCytoplasmic polyadenylation regulates mRNA stability and translation and is required for early development and synaptic plasticity. The GLD-2 poly(A) polymerase catalyzes cytoplasmic polyadenylation in the germline of metazoa. Among vertebrates, the enzyme is encoded by two isoforms of mRNA that differ only in the length of their 3′-UTRs. Here we focus on regulation of vertebrateGLD-2 mRNA. We show that the 3′-UTR of GLD-2 mRNA elicits its own polyadenylation and translational activation during frog oocyte maturation. We identify the sequence elements responsible for repression and activation, and demonstrate that CPEB and PUF proteins likely mediate repression in the resting oocyte. Regulated polyadenylation of GLD-2 mRNA is conserved, as are the key regulatory elements. Poly(A) tails of GLD-2 mRNA increase in length in the brain in response to neuronal stimulation, suggesting that a comparable system exists in that tissue. We propose a positive feedback circuit in which translation of GLD-2 mRNA is stimulated by its polyadenylation, thereby reinforcing the switch to polyadenylate and activate batteries of mRNAs
Characterization of a Conserved Transient Receptor Potential Channel Required for Spermatogenesis in Planarian Flatworms
No full textThe molecular processes underlying the control of external stimuli on development of the reproductive system remain to be understood. The Transient Receptor Potential superfamily of proteins (TRPs) consists of cation channels that respond to external stimuli and are abundant in the somatosensory as well as reproductive systems. Mammalian TRP-Melastatin 3 (TRPM3) channels are activated by heat and the neurosteroid pregnenolone. Here we characterize an ortholog of TRPM3 in the planarian flatworm Schmidtea mediterranea (Smed-TRPM3). Smed-TRPM3 was hypothesized to play a role in germline development due to enriched expression in the reproductive system of sexual planarians. In situ hybridization analysis revealed that Smed-TRPM3 is preferentially expressed in planarian testes and ovaries. Functional analysis by RNA interference (RNAi) revealed that Smed-TRPM3 promotes spermatogenesis, as sexual Smed-TRPM3(RNAi) planarians had fewer and less-developed testes compared to control knockdowns. Asexual Smed-TRPM3(RNAi) animals had fewer nanos+ clusters compared to controls which may indicate that the observed spermatogenesis defects are due to the loss of male germline stem cells. We hypothesize that Smed-TRPM3 responds to the hormone pregnenolone to ultimately regulate gonad development. Alternatively, Smed-TRPM3 may be regulating reproductive development in response to temperature.https://corescholar.libraries.wright.edu/urop_celebration/1107/thumbnail.jp
Tau Tubulin Kinase Is Required for Spermatogenesis and Development of Motile Cilia in Planarian Flatworms
No full textCilia are microtubule-based structures that protrude from the apical surface of cells to mediate motility, transport, intracellular signaling, and environmental sensing. Tau tubulin kinases (TTBKs) destabilize microtubules by phosphorylating microtubule-associated proteins (MAPs) of the MAP2/Tau family, but also contribute to the assembly of primary cilia during embryogenesis. Expression of TTBKs is enriched in testicular tissue, but their relevance to reproductive processes is unknown. We identified six TTBK homologues in the genome of the planarian Schmidtea mediterranea (Smed-TTBK-a, -b, -c, -d, -e, and -f), all of which are preferentially expressed in testes. Inhibition of TTBK paralogues by RNA interference (RNAi) revealed a specific requirement for Smed-TTBK-d in postmeiotic regulation of spermatogenesis. Disrupting expression of Smed-TTBK-d results in loss of spermatozoa, but not spermatids. In the soma, Smed-TTBK-d RNAi impaired the function of multiciliated epidermal cells in propelling planarian movement, as well as the osmoregulatory function of protonephridia. Decreased density and structural defects of motile cilia were observed in the epidermis of Smed-TTBK-d(RNAi) by phase contrast, immunofluorescence, and transmission electron microscopy. Altogether, these results demonstrate that members of the TTBK family of proteins are postmeiotic regulators of sperm development and also contribute to the formation of motile cilia in the soma
- …
