Biology Commons^™

Hsp70 And Hsp40 Functionally Interact With Soluble Mutant Huntingtin Oligomers In A Classic Atp-Dependent Reaction Cycle, Gregor P. Lotz, Justin Legleiter, Rebecca Aron, Emily M. Sontag, Shao-Yi Huang, Cheping Ng, Charles G. Glabe, Leslie M. Thompson, Paul J. Muchowski

Biological Sciences Faculty Research and Publications

Inclusion bodies of aggregated mutant huntingtin (htt) fragments are a neuropathological hallmark of Huntington disease (HD). The molecular chaperones Hsp70 and Hsp40 colocalize to inclusion bodies and are neuroprotective in HD animal models. How these chaperones suppress mutant htt toxicity is unclear but might involve direct effects on mutant htt misfolding and aggregation. Using size exclusion chromatography and atomic force microscopy, we found that mutant htt fragments assemble into soluble oligomeric species with a broad size distribution, some of which reacted with the conformation-specific antibody A11. Hsp70 associated with A11-reactive oligomers in an Hsp40- and ATP-dependent manner and inhibited their …

Structure And Expression Of Two Nuclear Receptor Genes In Marsupials: Insights Into The Evolution Of The Antisense Overlap Between The Α-Thyroid Hormone Receptor And Rev-Erbα, Brandon C. Rindfleisch, M. Scott Brown, John L. Vandeberg, Stephen Munroe

Biological Sciences Faculty Research and Publications

Background: Alternative processing of α-thyroid hormone receptor (TRα, NR1A1) mRNAs gives rise to two functionally antagonistic nuclear receptors: TRα1, the α-type receptor, and TRα2, a non-hormone binding variant that is found only in mammals. TRα2 shares an unusual antisense coding overlap with mRNA for Rev-erbα (NR1D1), another nuclear receptor protein. In this study we examine the structure and expression of these genes in the gray short-tailed opossum, Monodelphis domestica, in comparison with that of eutherian mammals and three other marsupial species, Didelphis virginiana, Potorous tridactylus and Macropus eugenii, in order to understand the evolution and regulatory …

Drosophila Vitelline Membrane Assembly: A Critical Role For An Evolutionarily Conserved Cysteine In The “Vm Domain” Of Sv23, T. Wu, Anita L. Manogaran, J. M. Beauchamp, Gail L. Waring

Biological Sciences Faculty Research and Publications

The vitelline membrane (VM), the oocyte proximal layer of the Drosophila eggshell, contains four major proteins (VMPs) that possess a highly conserved “VM domain” which includes three precisely spaced, evolutionarily conserved, cysteines (CX⁷CX⁸C). Focusing on sV23, this study showed that the three cysteines are not functionally equivalent. While substitution mutations at the first (C123S) or third (C140S) cysteines were tolerated, females with a substitution at the second position (C131S) were sterile. Fractionation studies showed that sV23 incorporates into a large disulfide linked network well after its secretion ceases, suggesting that post-depositional mechanisms are in place to …

Post‐Glacial Expansion Into The Paleozoic Plateau: Evidence Of An Ozarkian Refugium For The Ozark Minnow Notropis Nubilus (Teleostei: Cypriniformes), Peter B. Berendzen, J.F. Dugan, Tony Gamble

Biological Sciences Faculty Research and Publications

Genetic variation was examined within the Ozark minnow Notropis nubilus using complete mtDNA cytochrome b gene sequences from 160 individuals representing 30 localities to test hypotheses on the origin of the distribution. Phylogenetic analyses revealed three strongly supported clades of haplotypes consistent with geographic distributions: a clade from the Western Ozarks, a clade from the Southern Ozarks and a clade from the Northern Ozarks and upper Mississippi River basin. The estimated mean ages of these clades indicated that they diverged during pre-Illinoian glacial cycles extending from the late Pliocene into the early Pleistocene. Results of demographic analyses based on coalescent …

Circadian Disruption And Metabolic Disease: Findings From Animal Models, Deanna M. Arble, Kathryn Moynihan Ramsey, Joseph Bass, Fred W. Turek

Biological Sciences Faculty Research and Publications

Social opportunities and work demands have caused humans to become increasingly active during the late evening hours, leading to a shift from the predominantly diurnal lifestyle of our ancestors to a more nocturnal one. This voluntarily decision to stay awake long into the evening hours leads to circadian disruption at the system, tissue, and cellular levels. These derangements are in turn associated with clinical impairments in metabolic processes and physiology. The use of animal models for circadian disruption provides an important opportunity to determine mechanisms by which disorganization in the circadian system can lead to metabolic dysfunction in response to …

Reversible Deficiencies In Flagellar Beating And Axonemal Assembly, Mei Wei

Dissertations (1934 -)

Axonemal complexes in flagella are largely prepackaged in the cell body. As such, one mutation often results in the absence of the co-assembled components and permanent motility deficiencies. For example, a Chlamydomonas mutant defective in RSP4 in the radial spoke, which is critical for bend propagation, has paralyzed flagella that also lack the paralogue RSP6 and three additional radial spoke proteins. Intriguingly, recent studies showed that several mutant strains contain a mixed population of swimmers and paralyzed cells despite their identical genetic background. Here we report a cause underlying these variations. Two new mutants lacking RSP6 swim processively and other …

Role Of Ampk Throughout Meiotic Maturation In The Mouse Oocyte: Evidence For Promotion Of Polar Body Formation And Suppression Of Premature Activation, Stephen Downs, Ru Ya, Christopher C. Davis

Biological Sciences Faculty Research and Publications

This study was conducted to assess the role of AMPK in regulating meiosis in mouse oocytes from the germinal vesicle stage to metaphase II. Exposure of mouse cumulus cell-enclosed oocytes (CEO) and denuded oocytes (DO) during spontaneous maturation in vitro to AMPK-activating agents resulted in augmentation of the rate and frequency of polar body formation. Inhibitors of AMPK had an opposite, inhibitory effect. In addition, the AMPK inhibitor, compound C (Cmpd C) increased the frequency of oocyte activation. The stimulatory action of the AMPK-activating agent, AICAR, and the inhibitory action of Cmpd C were diminished if exposure was delayed, indicating …

Prolonged Space Flight-Induced Alterations In The Structure And Function Of Human Skeletal Muscle Fibres, Robert Fitts, S. W. Trappe, David Costill, Philip M. Gallagher, Andrew C. Creer, Patricia Colloton, Jim R. Peters, Janell Romatowski, J. L. Bain, Danny A. Riley

Biological Sciences Faculty Research and Publications

The primary goal of this study was to determine the effects of prolonged space flight (~180 days) on the structure and function of slow and fast fibres in human skeletal muscle. Biopsies were obtained from the gastrocnemius and soleus muscles of nine International Space Station crew members ~45 days pre- and on landing day (R+0) postflight. The main findings were that prolonged weightlessness produced substantial loss of fibre mass, force, and power with the hierarchy of the effects being soleus type I > soleus type II > gastrocnemius type I > gastrocnemius type II. Structurally, the quantitatively most important adaptation was fibre atrophy …

The Impact Of Lianas On 10 Years Of Tree Growth And Mortality On Barro Colorado Island, Panama, Laura L. Ingwell, S. Joseph Wright, Kristen K. Becklund, Stephen P. Hubbell, Stefan A. Schnitzer

Biological Sciences Faculty Research and Publications

1. Lianas compete intensely with trees, but few studies have examined long‐term effects of liana infestation on tree growth and mortality. We quantified the effects of lianas in tree crowns (n = 2907) and rooted within 2 m of trees (n = 1086) on growth and mortality of 30 tree species from 1995 to 2005 on Barro Colorado Island (BCI), Panama, documented liana infestation in tree crowns in 1996 and 2007 to determine the dynamics of liana infestation, and quantified liana infestation in the crowns of 3231 additional canopy trees (d.b.h. ≥20 cm) in 2007 to compare with …

Loss Of Individual Micrornas Causes Mutant Phenotypes In Sensitized Genetic Backgrounds In C. Elegans, John L. Brenner, Kristen L. Jasiewicz, Alisha F. Fahley, Benedict J. Kemp, Allison L. Abbott

Biological Sciences Faculty Research and Publications

MicroRNAs (miRNAs) are small, noncoding RNAs that regulate the translation and/or stability of their mRNA targets. Previous work showed that for most miRNA genes of C. elegans, single-gene knockouts did not result in detectable mutant phenotypes. This may be due, in part, to functional redundancy between miRNAs. However, in most cases, worms carrying deletions of all members of a miRNA family do not display strong mutant phenotypes. They may function together with unrelated miRNAs or with non-miRNA genes in regulatory networks, possibly to ensure the robustness of developmental mechanisms. To test this, we examined worms lacking individual miRNAs in …

Regulation Of The G2/M Transition In Rodent Oocytes, Stephen Downs

Biological Sciences Faculty Research and Publications

Regulation of maturation in meiotically competent mammalian oocytes is a complex process involving the carefully coordinated exchange of signals between the somatic and germ cell compartments of the ovarian follicle via paracrine and cell–cell coupling pathways. This review highlights recent advances in our understanding of how such signaling controls both meiotic arrest and gonadotropin-triggered meiotic resumption in competent oocytes and relates them to the historical context. Emphasis will be on rodent systems, where many of these new findings have taken place. A regulatory scheme is then proposed that integrates this information into an overall framework for meiotic regulation that demonstrates …

Lianas Suppress Tree Regeneration And Diversity In Treefall Gaps, Stefan A. Schnitzer, Walter P. Carson

Biological Sciences Faculty Research and Publications

Treefall gaps are hypothesized to maintain diversity by creating resource‐rich, heterogeneous habitats necessary for species coexistence. This hypothesis, however, is not supported empirically for shade‐tolerant trees, the dominant plant group in tropical forests. The failure of gaps to maintain shade‐tolerant trees remains puzzling, and the hypothesis implicated to date is dispersal limitation. In central Panama, we tested an alternative ‘biotic interference’ hypothesis: that competition between growth forms (lianas vs. trees) constrains shade‐tolerant tree recruitment, survival and diversity in gaps. We experimentally removed lianas from eight gaps and monitored them for 8 years, while also monitoring nine un‐manipulated control gaps. Removing …

Pkcα And Cpi-17 Expression And Spatial-Temporal Distribution With Activation In Pig Stomach Antrum And Fundus, Yu Zhang

Master's Theses (2009 -)

Smooth muscle contraction is a complicated process coordinated by contractile, regulatory and cytoskeletal proteins. The force generation depends on the phosphorylation of Myosin Regulatory Light Chain (MLC20). Myosin Light Chain Kinase (MLCK) and Myosin Light Chain Phosphatase (MLCP) are the two main regulators of the MLC20 phosphorylation level. MLCP is further controlled by two known pathways including the G protein coupled receptors (GPCRs)/ phospholipase C (PLC)/ diacylglycerol (DAG)/ protein kinase C (PKC)/ PKC-potentiated inhibitory protein for heterotrimeric myosin light chain phosphatase of 17 kDa (CPI-17) pathway. While messengers involved in this pathway have been proposed, studies on the details of …

Negative Plant–Soil Feedback Predicts Tree-Species Relative Abundance In A Tropical Forest, Scott A. Mangan, Stefan A. Schnitzer, Edward A. Herre, Keenan M.L. Mack, Mariana C. Valencia, Evelyn I. Sanchez, James D. Bever

Biological Sciences Faculty Research and Publications

The accumulation of species-specific enemies around adults is hypothesized to maintain plant diversity by limiting the recruitment of conspecific seedlings relative to heterospecific seedlings^1,2,3,4,5,6. Although previous studies in forested ecosystems have documented patterns consistent with the process of negative feedback^{7,8,9,10,11,12,13,14,15,16}, these studies are unable to address which classes of enemies (for example, pathogens, invertebrates, mammals) exhibit species-specific effects strong enough to generate negative feedback¹⁷, and whether …

Endocannabinoid Signalling: Has It Got Rhythm?, Linda K. Vaughn, Gerene Denning, Kara L. Stuhr, Harriet De Wit, Matthew N. Hill, Cecilia J. Hillard

Biomedical Sciences Faculty Research and Publications

Endogenous cannabinoid signalling is widespread throughout the body, and considerable evidence supports its modulatory role in many fundamental physiological processes. The daily and seasonal cycles of the relationship of the earth and sun profoundly affect the terrestrial environment. Terrestrial species have adapted to these cycles in many ways, most well studied are circadian rhythms and hibernation. The purpose of this review was to examine literature support for three hypotheses: (i) endocannabinoid signalling exhibits brain region-specific circadian rhythms; (ii) endocannabinoid signalling modulates the rhythm of circadian processes in mammals; and (iii) changes in endocannabinoid signalling contribute to the state of hibernation. …

Bioaugmentation For Improved Recovery Of Anaerobic Digesters After Toxicant Exposure, Anne Schauer-Gimenez, Daniel Zitomer, James Maki, Craig Struble

Biological Sciences Faculty Research and Publications

Bioaugmentation was investigated as a method to decrease the recovery period of anaerobic digesters exposed to a transient toxic event. Two sets of laboratory-scale digesters (SRT = 10 days, OLR = 2 g COD/L-day), started with inoculum from a digester stabilizing synthetic municipal wastewater solids (MW) and synthetic industrial wastewater (WW), respectively, were transiently exposed to the model toxicant, oxygen. Bioaugmented digesters received 1.2 g VSS/L-day of an H₂-utilizing culture for which the archaeal community was analyzed. Soon after oxygen exposure, the bioaugmented digesters produced 25–60% more methane than non-bioaugmented controls (p < 0.05). One set of digesters produced lingering high propionate concentrations, and bioaugmentation resulted in significantly shorter recovery periods. The second set of digesters did not display lingering propionate, and bioaugmented digesters recovered at the same time as non-bioaugmented controls. The difference in the effect of bioaugmentation on recovery may be due to differences between microbial communities of the digester inocula originally employed. In conclusion, bioaugmentation with an H₂-utilizing culture is a …

Mutant Huntingtin Fragments Form Oligomers In A Polyglutamine Length-Dependent Manner In Vitro And In Vivo, Justin Legleiter, Emily M. Sontag, Gregor P. Lotz, Ellen Sapp, Cheping Ng, Marian Difiglia, Leslie M. Thompson, Paul J. Muchowski

Biological Sciences Faculty Research and Publications

Huntington disease (HD) is caused by an expansion of more than 35–40 polyglutamine (polyQ) repeats in the huntingtin (htt) protein, resulting in accumulation of inclusion bodies containing fibrillar deposits of mutant htt fragments. Intriguingly, polyQ length is directly proportional to the propensity for htt to form fibrils and the severity of HD and is inversely correlated with age of onset. Although the structural basis for htt toxicity is unclear, the formation, abundance, and/or persistence of toxic conformers mediating neuronal dysfunction and degeneration in HD must also depend on polyQ length. Here we used atomic force microscopy to demonstrate mutant htt …

Annual Rainfall And Seasonality Predict Pan‐Tropical Patterns Of Liana Density And Basal Area, Saara J. Dewalt, Stefan A. Schnitzer, Jérôme Chave, Frans Bongers, Robyn J. Burnham, Zhiquan Cai, George B. Chuyong, David B. Clark, Corneille E.N. Ewango, Jeffrey J. Gerwing, Esteban Gortaire, Terese Hart, Guillermo Ibarra-Manriquez, Kalan Ickes, David Kenfack, Manuel J. Macía, Jean-Remy Makana, Miguel Martinez-Ramos, Joseph Mascaro, Sainge Moses, Helene C. Muller-Laudau, Marc P.E. Parren, Narayanaswamy Parthasarathy, Diego R. Perez-Salicrup, Francis E. Putz, Hugo Romero-Saltos, Duncan W. Thomas

Biological Sciences Faculty Research and Publications

We test the hypotheses proposed by Gentry and Schnitzer that liana density and basal area in tropical forests vary negatively with mean annual precipitation (MAP) and positively with seasonality. Previous studies correlating liana abundance with these climatic variables have produced conflicting results, warranting a new analysis of drivers of liana abundance based on a different dataset. We compiled a pan‐tropical dataset containing 28,953 lianas (≥2.5 cm diam.) from studies conducted at 13 Neotropical and 11 Paleotropical dry to wet lowland tropical forests. The ranges in MAP and dry season length (DSL) (number of months with mean rainfall <100 mm) represented by these datasets were 860–7250 mm/yr and 0–7 mo, respectively. Pan‐tropically, liana density and basal area decreased significantly with increasing annual rainfall and increased with increasing DSL, supporting the hypotheses of Gentry and Schnitzer. Our results suggest that much of the variation in liana density and basal area in the tropics can be accounted for by the relatively simple metrics of MAP and DSL.

Candida Albicans Adhesion And Biofilm Formation On Phosphated And Non-Phosphate Containing Poly(Methylmethacrylate) Polymers, Kathryn Elizabeth Ryan

Master's Theses (2009 -)

Denture-induced stomatitis is prevalent among prosthesis users, particularly the elderly and institutionalized where it has been estimated to be present in over 60-65% of denture wearers. Treatment of this clinical condition is problematic due to incomplete disinfection of the acrylic surface and rapid microbial re-colonization. Moreover, ingestion or aspiration of pathogens in denture plaque exposes the elderly and immunocompromised to unexpected infections.

Acrylic polymers have generally been used to replace missing teeth and periodontal tissues in edentulous or partially dentate patients. Currently, edentulous adults in the US population are common, with complete edentulism greater than 41% among Americans aged 65 …

Probing The Catalytic Roles Of Arg548 And Gln552 In The Carboxyl Transferase Domain Of The Rhizobium Etli Pyruvate Carboxylase By Site-Directed Mutagenesis, Saowapa Duangpan, Sarawut Jitrapakdee, Abdussalam Adina-Zada, Lindsay Byrne, Tonya N. Zeczycki, Martin St. Maurice, W. Wallace Cleland, John C. Wallace, Paul V. Attwood

Biological Sciences Faculty Research and Publications

The roles of Arg548 and Gln552 residues in the active site of the carboxyl transferase domain of Rhizobium etli pyruvate carboxylase were investigated using site-directed mutagenesis. Mutation of Arg548 to alanine or glutamine resulted in the destabilization of the quaternary structure of the enzyme, suggesting that this residue has a structural role. Mutations R548K, Q552N, and Q552A resulted in a loss of the ability to catalyze pyruvate carboxylation, biotin-dependent decarboxylation of oxaloacetate, and the exchange of protons between pyruvate and water. These mutants retained the ability to catalyze reactions that occur at the active site of the biotin carboxylase domain, …

Modulation Of L-Type Calcium Current By Gaba-B Receptor Activation In The Neonatal Rat Hippocampus, Jennifer Grace Bray

Dissertations (1934 -)

During the early postnatal period, the inhibitory neurotransmitter γ-aminobutyric acid (GABA) facilitates current through voltage-dependent L-type calcium channels by activating metabotropic GABA_B receptors in the rat hippocampus. In the present study, the effects of the GABA_B receptor agonist baclofen on L-type currents were tested using whole-cell voltage clamp recording on neurons isolated from the superior region of hippocampi obtained from pups of various ages to determine the exact time course of L-type current facilitation. The facilitation of L-type current by GABA_B receptors is more prominent during the second week of development.

One developmental process that L-type current …

Most, But Not All, Yeast Strains In The Deletion Library Contain The [Pin+] Prion, Anita L. Manogaran, Viviana M. Fajardo, Robert J. D. Reid, Rodney Rothstein, Susan W. Liebman

Biological Sciences Faculty Research and Publications

The yeast deletion library is a collection of over 5100 single gene deletions that has been widely used by the yeast community. The presence of a non-Mendelian element, such as a prion, within this library could affect the outcome of many large-scale genomic studies. We previously showed that the deletion library parent strain contained the [PIN⁺] prion. [PIN⁺] is the misfolded infectious prion form of the Rnq1 protein that displays distinct fluorescent foci in the presence of RNQ1–GFP and exists in different physical conformations, called variants. Here, we show that over 97% of the …

An Exonic Splicing Enhancer Within A Bidirectional Coding Sequence Regulates Alternative Splicing Of An Antisense Mrna, Valerie K. Salato, Nathaniel W. Rediske, Chao Zhang, Michelle Laura Hastings, Stephen Munroe

Biological Sciences Faculty Research and Publications

The discovery of increasing numbers of genes with overlapping sequences highlights the problem of expression in the context of constraining regulatory elements from more than one gene. This study identifies regulatory sequences encompassed within two genes that overlap in an antisense orientation at their 3’ ends. The genes encode the α-thyroid hormone receptor gene (TRα or NR1A1) and Rev-erbα (NR1D1). In mammals TRα pre-mRNAs are alternatively spliced to yield mRNAs encoding functionally antagonistic proteins: TRα1, an authentic thyroid hormone receptor; and TRα2, a non-hormone-binding variant that acts as a repressor. TRα2-specific splicing requires two regulatory elements that overlap with Rev-erbα …

Genetic Basis For Rhizobium Etli Ce3 O-Antigen O-Methylated Residues That Vary According To Growth Conditions, Kristylea J. Ojeda, Jodie M. Box, K. Dale Noel

Biological Sciences Faculty Research and Publications

The Rhizobium etli CE3 O antigen is a fixed-length heteropolymer with O methylation being the predominant type of sugar modification. There are two O-methylated residues that occur, on average, once per complete O antigen: a multiply O-methylated terminal fucose and 2-O methylation of a fucose residue within a repeating unit. The amount of the methylated terminal fucose decreases and the amount of 2-O-methylfucose increases when bacteria are grown in the presence of the host plant, Phaseolus vulgaris, or its seed exudates. Insertion mutagenesis was used to identify open reading frames required for the presence of these O-methylated …

Chlamydomonas Mutants Display Reversible Deficiencies In Flagellar Beating And Axonemal Assembly, Mei Wei, Priyanka Sivadas, Heather A. Owen, David R. Mitchell, Pinfen Yang

Biological Sciences Faculty Research and Publications

Axonemal complexes in flagella are largely prepackaged in the cell body. As such, one mutation often results in the absence of the co-assembled components and permanent motility deficiencies. For example, a Chlamydomonas mutant defective in RSP4 in the radial spoke (RS), which is critical for bend propagation, has paralyzed flagella that also lack the paralogue RSP6 and three additional RS proteins. Intriguingly, recent studies showed that several mutant strains contain a mixed population of swimmers and paralyzed cells despite their identical genetic background. Here we report a cause underlying these variations. Two new mutants lacking RSP6 swim processively and other …

A New Species Of Gekko (Squamata: Gekkonidae) From Tà Kóu Nature Reserve, Binh Thuan Province, Southern Vietnam, Van Tri Ngo, Tony Gamble

Biological Sciences Faculty Research and Publications

A new species of Gekko Laurenti is described from Ta Kou Mountain, an isolated granitic peak in Ta Kou Nature Reserve, Ham Thuan Nam district, Binh Thuan province, southern Vietnam. The species is distinguished from its congeners by its moderate size, with snout to vent length (SVL) reaching a maximum 107.0 mm; dorsal pattern of 5–8 white vertebral blotches between the nape and sacrum and 6–8 pairs of short white bars on the flanks; 11–14 precloacal pores in males; 14–17 longitudinal rows of smooth dorsal tubercles; and 18–20 broad lamellae beneath the fourth toe. Gekko takouensis sp. nov. is the …

Interaction Between The Biotin Carboxyl Carrier Domain And The Biotin Carboxylase Domain In Pyruvate Carboxylase From Rhizobium Etli, Adam D. Lietzan, Ann L. Menefee, Tonya N. Zeczycki, Sudhanshu Kumar, Paul V. Attwood, John C. Wallace, W. Wallace Cleland, Martin St. Maurice

Biological Sciences Faculty Research and Publications

Pyruvate carboxylase (PC) catalyzes the ATP-dependent carboxylation of pyruvate to oxaloacetate, an important anaplerotic reaction in mammalian tissues. To effect catalysis, the tethered biotin of PC must gain access to active sites in both the biotin carboxylase domain and the carboxyl transferase domain. Previous studies have demonstrated that a mutation of threonine 882 to alanine in PC from Rhizobium etli renders the carboxyl transferase domain inactive and favors the positioning of biotin in the biotin carboxylase domain. We report the 2.4 Å resolution X-ray crystal structure of the Rhizobium etli PC T882A mutant which reveals the first high-resolution description of …

Inhibitors Of Pyruvate Carboxylase, Tonya N. Zeczycki, Martin St. Maurice, Paul V. Attwood

Biological Sciences Faculty Research and Publications

This review aims to discuss the varied types of inhibitors of biotin-dependent carboxylases, with an emphasis on the inhibitors of pyruvate carboxylase. Some of these inhibitors are physiologically relevant, in that they provide ways of regulating the cellular activities of the enzymes e.g. aspartate and prohibitin inhibition of pyruvate carboxylase. Most of the inhibitors that will be discussed have been used to probe various aspects of the structure and function of these enzymes. They target particular parts of the structure e.g. avidin – biotin, FTP – ATP binding site, oxamate – pyruvate binding site, phosphonoacetate – binding site of the …

A Review Of Sex Determining Mechanisms In Geckos (Gekkota: Squamata), Tony Gamble

Biological Sciences Faculty Research and Publications

Geckos are a species-rich clade of reptiles possessing diverse sex determining mechanisms. Some species possess genetic sex determination, with both male and female heterogamety, while other species have temperature-dependent sex determination. I compiled information from the literature on the taxonomic distribution of these sex determining mechanisms in geckos. Using phylogenetic data from the literature, I reconstructed the minimum number of transitions among these sex determining mechanisms with parsimony-based ancestral state reconstruction. While only a small number of gecko species have been characterized, numerous changes among sex determining mechanisms were inferred. This diversity, coupled with the high frequency of transitions, makes …