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Jill A. Jenkins

Publications and source records attributed to Jill A. Jenkins.

At least 19 recordsLinked to original sources
USGS2019

Establishing genome sizes of focal fishery and aquaculture species along Baja California, Mexico

Genome size—the total haploid content of nuclear DNA— is constant in all cells in individuals within a species, but differs among species. Consequently, the genome size is a quantifiable genetic signature that not only characterizes a species, but it can reflect chromatin modifications, which play fundamental roles in most biological processes that are involved in the manipulation and expression of DNA. This characteristic makes the genome size a crucial parameter for genetic research on endemic aquatic species and for genetic manipulations in aquaculture species. Technologies for genetic assessments and improvements applied to fishery and aquaculture species use genome size values as a means by which hybrids, polyploids, and sex can be identified, when sex chromosomes exist. The objectives of this study were to determine genome sizes of aquatic species with economic and biological importance along the Pacific coast of Mexico, as well as to identify the appropriate reference standards for use in this study. Blood, hemolymph or milt were collected from 10 species occurring along the coast of Baja California: Sablefish Anoplopoma fimbria , Black Snapper Lutjanus novemfasciatus , California Halibut Paralichthys californicus , Pacific Sardine Sardinops sagax , Flag Rockfish Sebastes rubrivinctus , Starry Rockfish Sebastes constellatus, Totoaba Totoaba macdonaldi , Whiteleg Shrimp Litopenaeus vannamei and two Yellowtail Seriola lalandi and S. dorsalis . Nuclear DNA was stained with propidium iodide solution and the genome size was determined by flow cytometry, with results ranging from 0.61 pg (1.22 pg/diploid cell) to 2.59 pg (5.18 pg/diploid cell), with the smallest value in Sablefish and the largest in the Whiteleg Shrimp. No significant differences were detected ( P ≤ 0.05) among individuals of the same species; the likely reason behind any dissimilar DNA content values with those from the literature were differences in methodologies or variations in genetics. Red-ear Slider Turtle Trachemys scripta elegans 2.65 pg (5.30 pg/diploid cell) and Red Junglefowl Gallus gallus 1.27 pg (2.54 pg/diploid cell) were chosen as the standards for reference values. These results establish the basis for the Mexican National Aquatic Genetic Resources project supporting genetic improvements for aquaculture and conservation status parameters for fisheries species.

Baja California↗
USGS2019

Defensible standardized ploidy assessments for Grass Carp (Ctenopharyngodon idella, Cyprinidae) intercepted from the commercial supply chain

Although methods are in place through the U.S. Fish and Wildlife (USFWS) program for ploidy testing of feral caught Grass Carp ( Ctenopharyngodon idella ) and black carp ( Mylopharyngodon piceus ), no guidelines exist for carp hauled across state lines. Using 1200 Grass Carp purchased by undercover Ohio law enforcement during 2015–2016, we developed a standardized protocol for discriminating ploidy by using two parameters, nuclear size and DNA content. Bead standards at 2 μm or 4 μm were used to establish nuclear size from Nile Tilapia ( Oreochromis niloticus ), known diploid ( n = 20) and triploid (n = 20) Grass Carp blood, and cells derived from eyeballs of purchased field carp. The control for establishing DNA content was cryopreserved or fresh tilapia blood (2.40 pg). Time postmortem indicated nuclear size was similar over 4 days, but DNA quality from triploids was best at 24 h. Occasionally, only size or DNA content was measurable. Tilapia mean nuclear size ( n = 501 samples) was 4.61 μm (SE 0.05) (R 2 = 0.94). Known diploid and triploid blood nuclear sizes, compared with tilapia size, were 3.62 μm (SE 0.13) (R 2 = 0.96) and 7.58 μm (SE 0.27) (R 2 = 0.96), respectively. Mean field carp eye nuclear size was 5.83 μm (SE 0.13). Mean DNA content of cells from field carp eyes ( n = 698 fish) was 3.51 pg (SE 0.06). No diploid Grass Carp were detected in the USFWS certified triploid Grass Carp transports. This standard protocol reliably discriminates ploidy and can be used for enforcement of regulations that differ among state jurisdictions.

Journal of Great Lakes Research↗
USGS2018

Sperm quality biomarkers complement reproductive and endocrine parameters in investigating environmental contaminants in common carp (Cyprinus carpio) from the Lake Mead National Recreation Area

Lake Mead National Recreational Area (LMNRA) serves as critical habitat for several federally listed species and supplies water for municipal, domestic, and agricultural use in the Southwestern U.S. Contaminant sources and concentrations vary among the sub-basins within LMNRA. To investigate whether exposure to environmental contaminants is associated with alterations in male common carp ( Cyprinus carpio ) gamete quality and endocrine- and reproductive parameters, data were collected among sub-basins over 7 years (1999–2006). Endpoints included sperm quality parameters of motility , viability, mitochondrial membrane potential, count, morphology, and DNA fragmentation; plasma components were vitellogenin (VTG), 17ß-estradiol, 11-keto-testosterone, triiodothyronine, and thyroxine. Fish condition factor, gonadosomatic index, and gonadal histology parameters were also measured. Diminished biomarker effects were noted in 2006, and sub-basin differences were indicated by the irregular occurrences of contaminants and by several associations between chemicals (e.g., polychlorinated biphenyls, hexachlorobenzene , galaxolide, and methyl triclosan) and biomarkers (e.g., plasma thyroxine, sperm motility and DNA fragmentation). By 2006, sex steroid hormone and VTG levels decreased with subsequent reduced endocrine disrupting effects. The sperm quality bioassays developed and applied with carp complemented endocrine and reproductive data, and can be adapted for use with other species.

Lake Mead National Recreation Area↗
USGS2018

Assessing the risk of diploid grass carp Ctenopharyngodon idella in the certified triploid supply chain in Ohio

Non-native grass carp (Ctenopharyngodon idella) have been stocked in the United States for vegetation control since the 1970s, and recent evidence suggests some natural reproduction in the Great Lakes basin. Despite all states and provinces bordering Lake Erie either banning grass carp or requiring imports of only sterile, U.S. Fish and Wildlife Service (USFWS)-certified triploids, the majority of grass carp captured and analyzed from Lake Erie are diploid, or reproductively viable. Potential sources of diploid grass carp include illegal importation, compromises in the USFWS-certified triploid shipments, migration from legal diploid states, or natural reproduction resulting from diploid stockings prior to the 1988 Ohio law requiring only certified triploids. The goal of this study was to explore the risk that diploid grass carp occur in the USFWS-certified triploid supply chain destined for Ohio. During 2015 and 2016, undercover Ohio Department of Natural Resources-Division of Wildlife law enforcement purchased 1200 grass carp from 16 distributors, and overnighted 80 dissected grass carp head and eyeball sample shipments (n = 15 fish per shipment) for ploidy analysis by flow cytometry. Standardized methods for both field and laboratory processing were established. No diploid grass carp were detected in these collections, indicating fidelity of the USFWS-certified triploid grass carp supply chain in Ohio. Thus, these shipments are not a likely source of diploid grass carp in Lake Erie. This study is the first large-scale evaluation of the potential for ecological risk from diploid grass carp occurrence in USFSW-certified shipments of triploids for national distribution.

Ohio↗
USGS2017

An accurate method for measuring triploidy of larval fish spawns

A standard flow cytometric protocol was developed for estimating triploid induction in batches of larval fish. Polyploid induction treatments are not guaranteed to be 100% efficient, thus the ability to quantify the proportion of triploid larvae generated by a particular treatment helps managers to stock high-percentage spawns and researchers to select treatments for efficient triploid induction. At 3 d posthatch, individual Grass Carp Ctenopharyngodon idella were mechanically dissociated into single-cell suspensions; nuclear DNA was stained with propidium iodide then analyzed by flow cytometry. Following ploidy identification of individuals, aliquots of diploid and triploid cell suspensions were mixed to generate 15 levels (0–100%) of known triploidy ( n = 10). Using either 20 or 50 larvae per level, the observed triploid percentages were lower than the known, actual values. Using nonlinear regression analyses, quadratic equations solved for triploid proportions in mixed samples and corresponding estimation reference plots allowed for predicting triploidy. Thus, an accurate prediction of the proportion of triploids in a spawn can be made by following a standard larval processing and analysis protocol with either 20 or 50 larvae from a single spawn, coupled with applying the quadratic equations or reference plots to observed flow cytometry results. Due to the universality of triploid DNA content being 1.5 times the diploid level and because triploid fish consist of fewer cells than diploids, this method should be applicable to other produced triploid fish species, and it may be adapted for use with bivalves or other species where batch analysis is appropriate.

North American Journal of Aquaculture↗
USGS2015

A pilot study testing a natural and a synthetic Molluscicide for controlling invasive apple snails ( Pomacea maculata )

Pomacea maculata (formerly P. insularum ), an apple snail native to South America, was discovered in Louisiana in 2008. These snails strip vegetation, reproduce at tremendous rates, and have reduced rice production and caused ecosystem changes in Asia. In this pilot study snails were exposed to two molluscicides, a tea ( Camellia sinensis ) seed derivative (TSD) or niclosamide monohydrate (Pestanal ® , 2′,5-dichloro-4′-nitrosalicylanilide, CAS #73360-56-2). Mortality was recorded after exposure to high or low concentrations (0.03 and 0.015 g/L for TSD, 1.3 and 0.13 mg/L for niclosamide). The TSD induced 100 % mortality at both concentrations. Niclosamide caused 100 % and 17 % mortality at high and low concentrations respectively. These molluscicides were also tested on potential biocontrol agents, the red swamp crayfish ( Procambarus clarkii ) and redear sunfish ( Lepomis microlophus ). No crayfish mortalities occurred at either concentration for either chemical, but sunfish experienced 100 % mortality with TSD (0.03 g/L), and 21 % mortality with niclosamide (0.13 mg/L).

Bulletin of Environmental Contamination and Toxico↗
USGS2015

Novel associations between contaminant body burdens and biomarkers of reproductive condition in male Common Carp along multiple gradients of contaminant exposure in Lake Mead National Recreation Area, USA

Adult male Common Carp were sampled in 2007/08 over a full reproductive cycle at Lake Mead National Recreation Area. Sites sampled included a stream dominated by treated wastewater effluent, a lake basin receiving the streamflow, an upstream lake basin (reference), and a site below Hoover Dam. Individual body burdens for 252 contaminants were measured, and biological variables assessed included physiological [plasma vitellogenin (VTG), estradiol-17β (E2), 11-ketotestosterone (11KT)] and organ [gonadosomatic index (GSI)] endpoints. Patterns in contaminant composition and biological condition were determined by Principal Component Analysis, and their associations modeled by Principal Component Regression. Three spatially distinct but temporally stable gradients of contaminant distribution were recognized: a contaminant mixture typical of wastewaters (PBDEs, methyl triclosan, galaxolide), PCBs, and DDTs. Two spatiotemporally variable patterns of biological condition were recognized: a primary pattern consisting of reproductive condition variables (11KT, E2, GSI), and a secondary pattern including general condition traits (condition factor, hematocrit, fork length). VTG was low in all fish, indicating low estrogenic activity of water at all sites. Wastewater contaminants associated negatively with GSI, 11KT and E2; PCBs associated negatively with GSI and 11KT; and DDTs associated positively with GSI and 11KT. Regression of GSI on sex steroids revealed a novel, nonlinear association between these variables. Inclusion of sex steroids in the GSI regression on contaminants rendered wastewater contaminants nonsignificant in the model and reduced the influence of PCBs and DDTs. Thus, the influence of contaminants on GSI may have been partially driven by organismal modes-of-action that include changes in sex steroid production. The positive association of DDTs with 11KT and GSI suggests that lifetime, sub-lethal exposures to DDTs have effects on male carp opposite of those reported by studies where exposure concentrations were relatively high. Lastly, this study highlighted advantages of multivariate/multiple regression approaches for exploring associations between complex contaminant mixtures and gradients and reproductive condition in wild fishes.

General and Comparative Endocrinology↗
USGS2015

Are endocrine and reproductive biomarkers altered in contaminant-exposed wild male Largemouth Bass (Micropterus salmoides) of Lake Mead, Nevada/Arizona, USA?

Male Largemouth Bass were sampled from two locations in Lake Mead (USA), a site influenced by treated municipal wastewater effluent and urban runoff (Las Vegas Bay), and a reference site (Overton Arm). Samples were collected in summer (July '07) and spring (March '08) to assess general health, endocrine and reproductive biomarkers, and compare contaminant body burdens by analyzing 252 organic chemicals. Sperm count and motility were measured in spring. Contaminants were detected at much higher frequencies and concentrations in fish from Las Vegas Bay than Overton Arm. Those with the highest concentrations included PCBs, DDTs, PBDEs, galaxolide, and methyl triclosan. Fish from Las Vegas Bay also had higher Fulton condition factor, hepatosomatic index, and hematocrit, and lower plasma 11-ketotestosterone concentration (KT). Gonadosomatic index (GSI) and sperm motility did not differ between sites, but sperm count was lower by nearly 50% in fish from Las Vegas Bay. A positive association between KT and GSI was identified, but this association was nonlinear. On average, maximal GSI was reached at sub-maximal KT concentrations. In conclusion, the higher concentration of contaminant body burdens coupled with reduced levels of KT and sperm count in fish from Las Vegas Bay suggest that male reproductive condition was influenced by contaminant exposures. Also, the nonlinear KT-GSI association provided a framework to understand why GSI was similar between male bass from both sites despite their large difference in KT, and also suggested the existence of post-gonadal growth functions of KT at high concentrations.

Arizona, Nevada↗
USGS2015

Hyla chrysoscelis (Cope’s gray treefrog) x Hyla cinerea (green treefrog): putative natural hybrid

Naturally–occurring hybrid treefrogs have been occasionally found in the eastern United States. However, these hybrids are almost always between members of the same species group. On 10 Jun 2014, at 2145 h, we located an individual making an unusual advertisement call along Bayou Manual Road in Sherburne Wildlife Management Area in the Atchafalaya Basin of south-central Louisiana, USA, and brought it back to the laboratory for further study. Physically, the treefrog appeared intermediate between a Green Treefrog and a Cope’s Gray Treefrog, which are members of different species groups. Call analysis also showed the individual to be intermediate between the two putative parental species. Flow cytometry was used to estimate the total genome size from nuclei of whole blood cells, and also determined the individual to be intermediate of the putative parental species. Despite vocalizing for mates, the hybrid did not appear to have viable spermatozoa, and was likely the result of an anomalous mis-mating event between a male Cope’s Gray Treefrog and a female Green Treefrog. To our knowledge, natural hybrids between a Cope’s Gray Treefrog and a Green Treefrog have not been previously reported.

Louisiana↗
USGS2014

Guidelines for use of fishes in research: Revised and expanded

The Guidelines for the Use of Fishes in Research (2014; 2014 Guidelines ), now available through the American fisheries Society (AFS) website and in print from the AFS bookstore, is a resource to aid researchers and regulatory authorities regarding responsible, scientifically valid research on fish and aquatic wildlife. The Guidelines for the Use of Fishes in Field Research (American Society of Ichthyologists and Herpetologists [ASIH] et al. 1987, 1988) emphasized field research and was followed by the 2004 Guidelines including laboratory research topics. Each version of the Guidelines has been jointly endorsed and/or published by the ASIH, the American Institute of Fishery Research Biologists (AIFRB), and AFS--each focusing on the scientific understanding, global conservation, and sustainability of aquatic animals, fisheries, and ecosystems. Changes with time necessitate revisions to make the Guidelines consistent with contemporary practices and scientific literature so to remain relevant as a technical resource. This document provides not only general principles relevant for field and laboratory research endeavors but includes specific requirements for researchers working within the United States and outside of the country. Within the scope of their expertise, the 2014 Uses of Fishers in Research (UFR) Committee members updated and revised sections, resulting in a 90-page 2014 Guidelines having undergone through peer review. As before, topical areas were addressed (see Table of Contents on page 416). Expanded coverage was provided on U.S. and international agencies and programs relevant to research with fishes. The Surgical Procedures and the Marking and Tagging section received special focus by a UFR Subcommittee. Feeds and Feeding and the Administration of Drugs, Biologics and Other Chemicals are just some of the newly added topics. The 2014 Guidelines is user-friendly by way of hyperlinks to external Internet sites, intradocument sections, and tables of acronyms with corresponding terms, low regulatory priority drugs, and Office of International des Epizooties notifiable disease agents. Again, the Institutional Animal Care and Use Committee (IACUC) role is explained, expectations for research are provided, and a brief checklist for IACUC readiness is included. Overall, the ,i>2014 Guidelines is the taxon-specific resource for our professional societies and is a principal document for standards on the care and use of fish and aquatic vertebrates in research.

Fisheries↗
USGS2014

Assessing reproductive and endocrine parameters in male largescale suckers ( Catostomus macrocheilus ) along a contaminant gradient in the lower Columbia River, USA

Persistent organochlorine pollutants such as polychlorinated biphenyls (PCBs), dichlorodiphenyldichloroethylene (p,p′-DDE), and polybrominated diphenyl ethers (PBDEs) are stable, bioaccumulative, and widely found in the environment, wildlife, and the human population. To explore the hypothesis that reproduction in male fish is associated with environmental exposures in the lower Columbia River (LCR), reproductive and endocrine parameters were studied in male resident, non-anadromous largescale sucker (Catostomus macrocheilus) (LSS) in the same habitats as anadromous salmonids having conservation status. Testes, thyroid tissue and plasma collected in 2010 from Longview (LV), Columbia City (CC), and Skamania (SK; reference) were studied. Sperm morphologies and thyrocyte heights were measured by light microscopy, sperm motilities by computer-assisted sperm motion analysis, sperm adenosine triphosphate (ATP) with luciferase, and plasma vitellogenin (VTG), thyroxine (T4), and triiodothyronine (T3) by immunoassay. Sperm apoptosis, viability, mitochondrial membrane potential, nuclear DNA fragmentation, and reproductive stage were measured by flow cytometry. Sperm quality parameters (except counts) and VTG were significantly different among sites, with correlations between VTG and 7 sperm parameters. Thyrocyte heights, T4, T3, gonadosomatic index and Fulton's condition factor differed among sites, but not significantly. Sperm quality was significantly lower and VTG higher where liver contaminants and water estrogen equivalents were highest (LV site). Total PCBs (specifically PCB-138, -146, -151, -170, -174, -177, -180, -183, -187, -194, and -206) and total PBDEs (specifically BDE-47, -100, -153, and -154) were negatively correlated with sperm motility. PCB-206 and BDE-154 were positively correlated with DNA fragmentation, and pentachloroanisole and VTG were positively correlated with sperm apoptosis and negatively correlated with ATP. BDE-99 was positively correlated with sperm counts and motility; T4 was negatively correlated with counts and positively correlated with motility, thus indicating possible androgenic mechanisms and thyroid endocrine disruption. Male LSS proved to be an informative model for studying reproductive and endocrine biomarkers in the LCR.

Oregon;Washington↗
USGS2014

Grass carp in the Great Lakes region: establishment potential, expert perceptions, and re-evaluation of experimental evidence of ecological impact

Intentional introductions of nonindigenous fishes are increasing globally. While benefits of these introductions are easily quantified, assessments to understand the negative impacts to ecosystems are often difficult, incomplete, or absent. Grass carp (Ctenopharyngodon idella) was originally introduced to the United States as a biocontrol agent, and recent observations of wild, diploid individuals in the Great Lakes basin have spurred interest in re-evaluating its ecological risk. Here, we evaluate the ecological impact of grass carp using expert opinion and a suite of the most up-to-date analytical tools and data (ploidy assessment, eDNA surveillance, species distribution models (SDMs), and meta-analysis). The perceived ecological impact of grass carp by fisheries experts was variable, ranging from unknown to very high. Wild-caught triploid and diploid individuals occurred in multiple Great Lakes waterways, and eDNA surveillance suggests that grass carp are abundant in a major tributary of Lake Michigan. SDMs predicted suitable grass carp climate occurs in all Great Lakes. Meta-analysis showed that grass carp introductions impact both water quality and biota. Novel findings based on updated ecological impact assessment tools indicate that iterative risk assessment of introduced fishes may be warranted.

Great Lakes Basin↗
USGS2014

Proper handling of animal tissues from the field to the laboratory supports reliable biomarker endpoints

In the endeavor to assess potential effects to the Gulf of Mexico ecosystem from the Mississippi Canyon 252 incident, referred to as the Deepwater Horizon oil spill, various environmental data have been collected. Whereas initial efforts have included satellite tracking and sediment and water sampling to estimate the geographical scope of oiling, research on biological samples can provide insights into potential physiological responses to oil if it was present in the food web, sediment, or water column. Fish species are ideal model organisms for studying responses to water- and sediment-borne contaminants due to their life history (Jenkins et al. 2014), and several Gulf of Mexico fish species were studied by scientists after this incident. Typical field data collected on fish reflect organism condition and include observations such as fish length, weight, gonad condition, condition factor (weight in relation to length), parasite load, and color of organs (Schmitt and Dethloff 2000). However, if physiological responses occurred due to oil exposure, effects would not be immediately visible using organism-level observations alone. Changes occur first at the organ, tissue, cell, or molecular levels, and these responses can be measured by using biomarker assays (van der Oost et al. 2003).

Book chapter↗
USGS2013

First evidence of grass carp recruitment in the Great Lakes Basin

We use aging techniques, ploidy analysis, and otolith microchemistry to assess whether four grass carp Ctenopharyngodon idella captured from the Sandusky River, Ohio were the result of natural reproduction within the Lake Erie Basin. All four fish were of age 1 +. Multiple lines of evidence indicate that these fish were not aquaculture-reared and that they were most likely the result of successful reproduction in the Sandusky River. First, at least two of the fish were diploid; diploid grass carp cannot legally be released in the Great Lakes Basin. Second, strontium:calcium (Sr:Ca) ratios were elevated in all four grass carp from the Sandusky River, with elevated Sr:Ca ratios throughout the otolith transect, compared to grass carp from Missouri and Arkansas ponds. This reflects the high Sr:Ca ratio of the Sandusky River, and indicates that these fish lived in a high-strontium environment throughout their entire lives. Third, Sandusky River fish were higher in Sr:Ca ratio variability than fish from ponds, reflecting the high but spatially and temporally variable strontium concentrations of southwestern Lake Erie tributaries, and not the stable environment of pond aquaculture. Fourth, Sr:Ca ratios in the grass carp from the Sandusky River were lower in their 2011 growth increment (a high water year) than the 2012 growth increment (a low water year), reflecting the observed inverse relationship between discharge and strontium concentration in these rivers. We conclude that these four grass carp captured from the Sandusky River are most likely the result of natural reproduction within the Lake Erie Basin.

Ohio↗
USGS2013

Reproductive health of yellow perch Perca flavescens in selected tributaries of the Chesapeake Bay

Reduced recruitment of yellow perch has been noted for a number of years in certain urbanized watersheds (South and Severn Rivers) of the Chesapeake Bay. Other rapidly developing watersheds such as Mattawoman Creek are more recently showing evidence of reduced recruitment of anadromous fishes. In this study, we used a battery of biomarkers to better document the reproductive health of adult yellow perch collected during spring spawning in 2007–2009. Perch were collected in the South and Severn Rivers, Mattawoman Creek and the less developed Choptank and Allen's Fresh watersheds for comparison. Gonadosomatic indices, plasma reproductive hormone concentrations, plasma vitellogenin concentrations and gonad histology were evaluated in mature perch of both sexes. In addition, sperm quantity (cell counts) and quality (total and progressive motility, spermatogenic stage and DNA integrity), were measured in male perch. Many of these biomarkers varied annually and spatially, with some interesting statistical results and trends. Male perch from the Choptank and Allen's Fresh had generally higher sperm counts. In 2008 counts were significantly lower in the perch from the Severn when compared to other sites. The major microscopic gonadal abnormality in males was the proliferation of putative Leydig cells, observed in testes from Severn and less commonly, Mattawoman Creek perch. Observations that could significantly impact egg viability were an apparent lack of final maturation, abnormal yolk and thin, irregular zona pellucida. These were observed primarily in ovaries from Severn, South and less commonly Mattawoman Creek perch. The potential association of these observations with urbanization, impervious surface and chemical contaminants is discussed.

Maryl;Virginia↗
USGS2013

Development of a novel flow cytometric approach to evaluate fish sperm chromatin using fixed samples

The integrity of the paternal DNA is essential for the accurate transmission of genetic information, yet fertilization is not inhibited by chromatin breakage. Some methods are available for the sensitive detection of DNA damage and can be applied in studies of environmental toxicology, carcinogenesis, aging, and assisted reproduction techniques in both clinical and experimental settings. Because semen samples obtained from remote locations undergo chromatin damage prior to laboratory assessment, the present study was undertaken to evaluate treatments for effective chromatin staining in the development of a DNA fragmentation assay using fixed milt from yellow perch (Perca flavescens). Similar to the sperm chromatin structure assay (SCSA), susceptibility of nuclear DNA to acid-induced denaturation was measured by flow cytometry (FCM). Use of 10% buffered formalin for milt fixation allowed easier peak discrimination than 4% paraformaldehyde. The effects of time and temperature of incubation in 0.08 N HCl were evaluated in order to determine the ideal conditions for promoting DNA decondensation and making strand breaks more available for staining and detection by FCM. The best results were obtained with incubation at 37°C for 1 minute, followed by cold propidium iodide staining for 30 minutes.

Conference Paper↗
USGS2011

Sperm quality assessments for endangered razorback suckers Xyrauchen texanus

Flow cytometry (FCM) and computer-assisted sperm motion analysis (CASA) methods were developed and validated for use with endangered razorback suckers Xyrauchen texanus collected ( n =64) during the 2006 spawning season. Sperm motility could be activated within osmolality ranges noted during milt collections (here 167&ndash;343 mOsm/kg). We hypothesized that sperm quality of milt collected into isoosmotic (302 mOsm/kg) or hyperosmotic (500 mOsm/kg) Hanks' balanced salt solution would not differ. Pre-freeze viabilities were similar between osmolalities (79%&plusmn;6 (S.E.M.) and 76%&plusmn;7); however, post-thaw values were greater in hyperosmotic buffer (27%&plusmn;3 and 12%&plusmn;2; P =0.0065), as was mitochondrial membrane potential (33%&plusmn;4 and 13%&plusmn;2; P =0.0048). Visual estimates of pre-freeze motility correlated with total ( r =0.7589; range 23&ndash;82%) and progressive motility ( r =0.7449) by CASA and were associated with greater viability ( r =0.5985; P <0.0001). Count (FCM) was negatively correlated with post-thaw viability ( r =-0.83; P =0.0116) and mitochondrial function ( r =-0.91; P =0.0016). By FCM-based assessments of DNA integrity, whereby increased fluorochrome binding indicated more fragmentation, higher levels were negatively correlated with count ( r =-0.77; P <0.0001) and pre-freeze viabilities ( r =-0.66; P =0.0004). Fragmentation was higher in isotonic buffer ( P =0.0234). To increase reproductive capacity of natural populations, the strategy and protocols developed can serve as a template for use with other imperiled fish species, biomonitoring, and genome banking.

Reproduction↗