Viable Gametes Research Articles

Impaired gamete production and viability in Atlantic croaker collected throughout the 20,000 km2 hypoxic region in the northern Gulf of Mexico

The long-term impacts of recent marked increases in the incidence and extent of hypoxia (dissolved oxygen <2mg/L) in coastal regions worldwide on fisheries and ecosystems are unknown. Reproductive impairment was investigated in Atlantic croaker collected in 2010 from the extensive coastal hypoxic region in the northern Gulf of Mexico. Potential fecundity was significantly lower in croaker collected throughout the ~20,000km2 hypoxic region than in croaker from normoxic sites. In vitro bioassays of gamete viability showed reductions in oocyte maturation and sperm motility in croaker collected from the hypoxic sites in response to reproductive hormones which were accompanied by decreases in gonadal levels of membrane progestin receptor alpha, the receptor regulating these processes. The finding that environmental hypoxia exposure reduces oocyte viability in addition to decreasing oocyte production in croaker suggests that fecundity estimates need to be adjusted to account for the decrease in oocyte maturation.

Sperm motility patterns as a tool for evaluating differences in sperm quality across gonad development stages in the sea urchin Paracentrotus lividus (Lmk, 1816)

Reproductive biotechnologies provide innovative support tools which are increasingly being applied to aquatic species. The development of tools for the assessment of changes in gamete quality as a function of gonad stage is a key issue in the establishment of species-specific protocols for gamete management and embryo production that guarantee the supply of high quality samples.The aim of the present study was to evaluate the sperm motility parameters, during the various phases of the gonad cycle, of Paracentrotus lividus specimens sampled from a population living along the mid-to-lower Adriatic coast of Italy. In this location, particularly favourable environmental conditions enable a prolonged reproductive period, and gonads containing mature gametes (whether developing or relict after spawning events) have been recorded nearly all year round. Specifically, each collected specimen was assigned a gonad stage following histological analysis and the sperm motility parameters, recorded by computerised analysis, were evaluated in relation to the assigned values. In addition, their fertilisation capacity was evaluated. Sperm motility was found to change during the gonad cycle: the highest motility percentages (>90%) and sperm velocities (curvilinear velocity >300 µm/s) were observed during the spawning stage. Conversely, no effect on the fertilisation capacity was observed (>85%, regardless of the gonad stage). It can therefore be concluded that an objective assessment of sperm motility parameters, mainly velocity levels, is a helpful tool for evaluating the quality of P. lividus semen samples on collection, as it makes it possible to identify samples from mature and spawning individuals. Statement of relevanceThe development of reproductive biotechnologies in aquaculture depends on the continuous supply of viable gametes, and on the development of assessment tools able to discern among different gamete physiological conditions. Sperm velocity evaluations by computerised analysis proved to be able to discern samples coming from mature and in spawning sea urchins, those having the best physiological conditions and motility values.

Arabidopsis TAF1 is an MRE11-interacting protein required for resistance to genotoxic stress and viability of the male gametophyte.

SummaryRepair of DNA double‐strand breaks (DSBs) by recombination pathways is essential for plant growth and fertility. The recombination endonuclease MRE11 plays important roles in sensing and repair of DNA DSBs. Here we demonstrate protein interaction between Arabidopsis MRE11 and the histone acetyltransferase TAF1, a TATA‐binding protein Associated Factor (TAF) of the RNA polymerase II transcription initiation factor complex TFIID. Arabidopsis has two TAF1 homologues termed TAF1 and TAF1b and mutant taf1b lines are viable and fertile. In contrast, taf1 null mutations are lethal, demonstrating that TAF1 is an essential gene. Heterozygous taf1 +/− plants display abnormal segregation of the mutant allele resulting from defects in pollen tube development, indicating that TAF1 is important for gamete viability. Characterization of an allelic series of taf1 lines revealed that hypomorphic mutants are viable but display developmental defects and reduced plant fertility. Hypersensitivity of taf1 mutants lacking the C‐terminal bromodomain to X‐rays and mitomycin C, but not to other forms of abiotic stress, established a specific role for TAF1 in plant DNA repair processes. Collectively these studies reveal a function for TAF1 in plant resistance to genotoxic stress, providing further insight into the molecular mechanisms of the DNA damage response in plants.

Reduced Crossover Interference and Increased ZMM-Independent Recombination in the Absence of Tel1/ATM.

Meiotic recombination involves the repair of double-strand break (DSB) precursors as crossovers (COs) or noncrossovers (NCOs). The proper number and distribution of COs is critical for successful chromosome segregation and formation of viable gametes. In budding yeast the majority of COs occurs through a pathway dependent on the ZMM proteins (Zip2-Zip3-Zip4-Spo16, Msh4-Msh5, Mer3), which form foci at CO-committed sites. Here we show that the DNA-damage-response kinase Tel1/ATM limits ZMM-independent recombination. By whole-genome mapping of recombination products, we find that lack of Tel1 results in higher recombination and reduced CO interference. Yet the number of Zip3 foci in tel1Δ cells is similar to wild type, and these foci show normal interference. Analysis of recombination in a tel1Δ zip3Δ double mutant indicates that COs are less dependent on Zip3 in the absence of Tel1. Together these results reveal that in the absence of Tel1, a significant proportion of COs occurs through a non-ZMM-dependent pathway, contributing to a CO landscape with poor interference. We also see a significant change in the distribution of all detectable recombination products in the absence of Tel1, Sgs1, Zip3, or Msh4, providing evidence for altered DSB distribution. These results support the previous finding that DSB interference depends on Tel1, and further suggest an additional level of DSB interference created through local repression of DSBs around CO-designated sites.

Two separable functions of Ctp1 in the early steps of meiotic DNA double-strand break repair.

Meiotic programmed DNA double-strand break (DSB) repair is essential for crossing-over and viable gamete formation and requires removal of Spo11-oligonucleotide complexes from 5′ ends (clipping) and their resection to generate invasive 3′-end single-stranded DNA (resection). Ctp1 (Com1, Sae2, CtIP homolog) acting with the Mre11-Rad50-Nbs1 (MRN) complex is required in both steps. We isolated multiple S. pombe ctp1 mutants deficient in clipping but proficient in resection during meiosis. Remarkably, all of the mutations clustered in or near the conserved CxxC or RHR motif in the C-terminal portion. The mutants tested, like ctp1Δ, were clipping-deficient by both genetic and physical assays­. But, unlike ctp1Δ, these mutants were recombination-proficient for Rec12 (Spo11 homolog)-independent break-repair and resection-proficient by physical assay. We conclude that the intracellular Ctp1 C-terminal portion is essential for clipping, while the N-terminal portion is sufficient for DSB end-resection. This conclusion agrees with purified human CtIP resection and endonuclease activities being independent. Our mutants provide intracellular evidence for separable functions of Ctp1. Some mutations truncate Ctp1 in the same region as one of the CtIP mutations linked to the Seckel and Jawad severe developmental syndromes, suggesting that these syndromes are caused by a lack of clipping at DSB ends that require repair.

Egg Viability, Mating Frequency and Male Mating Ability Evolve in Populations of Drosophila melanogaster Selected for Resistance to Cold Shock.

BackgroundAbility to resist temperature shock is an important component of fitness of insects and other ectotherms. Increased resistance to temperature shock is known to affect life-history traits. Temperature shock is also known to affect reproductive traits such as mating ability and viability of gametes. Therefore selection for increased temperature shock resistance can affect the evolution of reproductive traits.MethodsWe selected replicate populations of Drosophila melanogaster for resistance to cold shock. We then investigated the evolution of reproductive behavior along with other components of fitness- larval survivorship, adult mortality, fecundity, egg viability in these populations.ResultsWe found that larval survivorship, adult mortality and fecundity post cold shock were not significantly different between selected and control populations. However, compared to the control populations, the selected populations laid significantly higher percentage of fertile eggs (egg viability) 24 hours post cold shock. The selected populations had higher mating frequency both with and without cold shock. After being subjected to cold shock, males from the selected populations successfully mated with significantly more non-virgin females and sired significantly more progeny compared to control males.ConclusionsA number of studies have reported the evolution of survivorship in response to selection for temperature shock resistance. Our results clearly indicate that adaptation to cold shock can involve changes in components of reproductive fitness. Our results have important implications for our understanding of how reproductive behavior can evolve in response to thermal stress.

Larval ecology of the fluted giant clam, Tridacna squamosa, and its potential effects on dispersal models

Biophysical models are increasingly being used to visualise and predict dispersal and connectivity of marine larvae, providing the opportunity to examine spatial and temporal patterns that are difficult to assess in the field. The quality of the biology component of these models, however, often lags behind that of the physical data. Hence, quantifying and parameterising species-specific autecological information are critical steps in advancing the reliability of larval transport simulations. Here we quantify three hitherto untested aspects of the larval ecology of the fluted giant clam, Tridacna squamosa: 1) fertilisation success in relation to gamete age, 2) larval swimming speeds, and 3) settlement competency, and discuss how these factors may affect model predictions of giant clam larval dispersal and recruitment. Through laboratory experiments, we found that T. squamosa gametes were fertilisable for up to 8h, but viability reduced with age. As giant clams are synchronistic spawners, this reduced gamete viability can impede fertilisation success if individuals are too distant from spawning neighbours. We also determined that ciliated T. squamosa larvae are not strong swimmers (104.0 to 1010.6μms−1), but appear able to alter their depth distribution and actively select settlement sites. Average swimming speed peaked 6days post-spawning, and subsequent reduction in speeds suggests ‘readiness’ for settlement. Trials indicated that the settlement competency period in T. squamosa is 14days. No gregarious settlement was observed amongst conspecifics but settlement-competent larvae responded positively to associative cues from fresh crustose coralline algae. All three of these T. squamosa larval traits have the potential to influence the outcomes and interpretations of model simulations.

Mitochondrial ATP synthase is dispensable in blood-stage Plasmodium berghei rodent malaria but essential in the mosquito phase

Mitochondrial ATP synthase is driven by chemiosmotic oxidation of pyruvate derived from glycolysis. Blood-stage malaria parasites eschew chemiosmosis, instead relying almost solely on glycolysis for their ATP generation, which begs the question of whether mitochondrial ATP synthase is necessary during the blood stage of the parasite life cycle. We knocked out the mitochondrial ATP synthase β subunit gene in the rodent malaria parasite, Plasmodium berghei, ablating the protein that converts ADP to ATP. Disruption of the β subunit gene of the ATP synthase only marginally reduced asexual blood-stage parasite growth but completely blocked mouse-to-mouse transmission via Anopheles stephensi mosquitoes. Parasites lacking the β subunit gene of the ATP synthase generated viable gametes that fuse and form ookinetes but cannot progress beyond this stage. Ookinetes lacking the β subunit gene of the ATP synthase had normal motility but were not viable in the mosquito midgut and never made oocysts or sporozoites, thereby abrogating transmission to naive mice via mosquito bite. We crossed the self-infertile ATP synthase β subunit knockout parasites with a male-deficient, self-infertile strain of P. berghei, which restored fertility and production of oocysts and sporozoites, which demonstrates that mitochondrial ATP synthase is essential for ongoing viability through the female, mitochondrion-carrying line of sexual reproduction in P. berghei malaria. Perturbation of ATP synthase completely blocks transmission to the mosquito vector and could potentially be targeted for disease control.

Reproductive capacity of a marine species (Octopus tetricus) within a recent range extension area

To persist in the face of environmental change, species must adjust to the new conditions or change their geographical distribution, e.g. by range extension. Success for individuals within a zone of range extension requires the new environment to support their capacity to produce viable gametes and survival of the offspring. Reproductive characteristics of the polewards range-shifting Octopus tetricus were examined within the new range off north-eastern Tasmania, Australia, to assess whether it is likely to successfully establish in this extended area of its range. Approximately 44% of captured males and 14% of captured females were mature. Mature females with developing eggs were found throughout the year. Greater numbers of mature females were observed during the austral summer and spring, whereas mature males were observed all year round. Fecundity was high and developing embryos appeared to be viable. Our results suggest that O. tetricus is successfully reproducing beyond its historical range, the reproductive cycle is timed to favourable environmental conditions, and the population has the potential to be self-sustainable. The reproductive biology of O. tetricus may thus facilitate the establishment and prevalence of the population into new environments beyond the known historical distribution.

Binding Dynamics of the Holliday Junction with Yeast MutS Homolog Msh4-Msh5

MutS homologs (Msh) are conserved in all organisms and they are involved in the process of mismatch recognition and repair. In Saccharomyces cerevisiae there are five MutS Homologs (Msh2 through Msh6) that participate in repair and recombination processes. The heterodimeric protein complexes, Msh2-Msh3 and Msh2-Msh6, play a role in mismatch repair. MutS homolog Msh4 and Msh5 are not involved in mismatch recognition and repair and genetic studies in S. cerevisiae and mouse indicate that Msh4-Msh5 are responsible for gamete viability during meiosis, recombination and chromosomal segregation. Recent studies have shown that human Msh4-Msh5 recognizes and stabilizes Holliday or four-way DNA Junctions (4WJ), an intermediate in double stranded break repair. Our efforts are focused on elucidating structure-function relationships of S. cerevisiae MutS homolog Msh4-Msh5 by specifically studying the binding interaction of Msh4-Msh5 with DNA 4WJs. We have successfully expressed and purified S. cerevisiae Msh4-Msh5 in E. coli cells as both a heterodimeric protein complex as well as Msh4 and Msh5 monomers. Our initial data demonstrates that the purified proteins are active and binds with high affinity to DNA 4WJ. The binding affinity is in the nanomolar range and similar to that previously reported for human Msh4-Msh5. To study the effect of Msh4-Msh5 on junction conformation, we are using Forster resonance energy transfer. These measurements also probe whether Msh4-Msh5 preferentially binds to the open or stacked form of the junction. These measurements will also address whether stabilization of the stacked conformation is functionally related to suppression of recombination.

Motility, viability and calcium in the sperm cells

AbstractSperm cells are complicated in vitro models. Their viability is limited, and physiology is complex. The study of their properties is of great application in the animal production as viable and functional gametes are essential. It has been shown that the decrease of sperm cell viability parallels an increase of the reactive oxygen species (ROS). Reactive oxygen species is secondary to normal metabolic processes of the cell-like flagellar movement. There is evidence of strategies that reduce ROS levels by using exogenous or endogenous antioxidants with the intention that seminal plasma protects the sperm cells and increases viability. Perhaps viability can increase by reducing that flagellar movement which is regulated by calcium. The phenomenon has not been fully characterized, but it is established that in certain mammalian models, the entrance of calcium via specific channels such as CATsper or voltage-dependent channels, signals flagellar movement. Previous reports have indicated that a change i...

Factors relevant to pre‐veliger nutrition ofTridacnidae giant clams

AbstractTridacnid giant clams are of commercial interest for their nutritional, economic, and ecological significance throughout theIndo‐Pacific andOceania. A major impediment to culturing tridacnid giant clams is larval mortality, typically &gt;96%. The effects of suspended and particulate nutrients on tridacnid veliger development have been examined, but factors relevant to the nutritional condition of oocytes and trochophore larvae are unknown. This is significant because the nutritional transition from trochophore to veliger coincides with rises in larval mortality. Our review examines culture techniques known to enhance gamete viability of several marine viable bivalves of commercial interest, and critically assesses whether such methods are applicable to tridacnids in culture conditions. Techniques for optimizing the nutritional requirements of pre‐veliger tridacnids such as broodstock conditioning by supplemental feeding, monitoring the condition of oocytes ready for release, water temperature, egg attributes such as size and biochemical composition, and nutrient loads in culture water chemistry are examined. We include suggestions for optimizing nutritional conditions from gametogenesis through embryonic development, and conclude with a primer of research opportunities based on gaps in our understanding of tridacnid pre‐veliger nutrition compared with other bivalves. A major conclusion is that culture protocols should include pre‐veliger nutritional fitness as a critical factor in enhancing larval survival, growth and development.

Emergence of apospory and bypass of meiosis via apomixis after sexual hybridisation and polyploidisation.

Hybridisation and polyploidy are major forces contributing to plant speciation. Homoploid (2x) and heteroploid (3x) hybrids, however, represent critical stages for evolution due to disturbed meiosis and reduced fertility. Apomixis – asexual reproduction via seeds – can overcome hybrid sterility, but requires several concerted alterations of developmental pathways to result in functional seed formation.Here, we analyse the reproductive behaviours of homo- and heteroploid synthetic hybrids from crosses between sexual diploid and tetraploid Ranunculus auricomus species to test the hypothesis that developmental asynchrony in hybrids triggers the shift to apomictic reproduction.Evaluation of male and female gametophyte development, viability and functionality of gametes shows developmental asynchrony, whereas seed set and germinability indicate reduced fitness in synthetic hybrids compared to sexual parents. We present the first experimental evidence for spontaneous apospory in most hybrids as an alternative pathway to meiosis, and the appearance of functional apomictic seeds in triploids. Bypassing meiosis permits these triploid genotypes to form viable seed and new polyploid progeny.Asynchronous development causes reduced sexual seed set and emergence of apospory in synthetic Ranunculus hybrids. Apomixis is functional in triploids and associated with drastic meiotic abnormalities. Selection acts to stabilise developmental patterns and to tolerate endosperm dosage balance shifts which facilitates successful seed set and establishment of apomictic lineages.

Variation in nickel accumulation in leaves, reproductive organs and floral rewards in two hyperaccumulating Brassicaceae species

Metal hyperaccumulation by plants involves the uptake and sequestration of extremely high concentrations of soil heavy metals. It is unclear, however, whether plants that hyperaccumulate heavy metals do so across all organs, including reproductive ones, and whether floral metal accumulation varies depending on whether plants require pollinator visitation for reproduction. We grew two species of nickel hyperaccumulators, one that requires pollinator visitation and the other an autonomous selfer, in two soil treatments: (1) control or (2) nickel-supplemented. We quantified nickel concentration in leaves, reproductive organs and floral rewards (pistils, anthers, pollen and nectar). Nickel accumulated into all organs, with the autonomously selfing species (Noccaea fendleri subsp. glauca) accumulating higher concentrations, especially in anthers and pistils. Streptanthus polygaloides incorporated nickel into nectar, but at lower concentrations than floral organs. Both species incorporated nickel into pollen. Nickel-hyperaccumulators incorporated nickel into all reproductive organs as well as rewards, suggesting possible reproductive consequences that may either be positive (e.g., elemental defense) or detrimental (e.g., reducing gamete viability or pollinator visitation) to plant fitness. Our work suggests that identifying any adaptive value of metal hyperaccumulation requires further study of floral metal accumulation and the reproductive consequences of metals in reproductive organs and rewards.

Genome rearrangements and pervasive meiotic drive cause hybrid infertility in fission yeast.

Hybrid sterility is one of the earliest postzygotic isolating mechanisms to evolve between two recently diverged species. Here we identify causes underlying hybrid infertility of two recently diverged fission yeast species Schizosaccharomyces pombe and S. kambucha, which mate to form viable hybrid diploids that efficiently complete meiosis, but generate few viable gametes. We find that chromosomal rearrangements and related recombination defects are major but not sole causes of hybrid infertility. At least three distinct meiotic drive alleles, one on each S. kambucha chromosome, independently contribute to hybrid infertility by causing nonrandom spore death. Two of these driving loci are linked by a chromosomal translocation and thus constitute a novel type of paired meiotic drive complex. Our study reveals how quickly multiple barriers to fertility can arise. In addition, it provides further support for models in which genetic conflicts, such as those caused by meiotic drive alleles, can drive speciation.DOI: http://dx.doi.org/10.7554/eLife.02630.001.

Laboratory procedures for human in vitro fertilization.

Successful and consistent outcomes in human in vitro fertilization (IVF) can be readily achieved by all IVF clinics through consideration and optimization of each procedure associated with the collection and processing of gametes, culminating in the resultant culture and transfer of healthy embryos. Furthermore, understanding the interactions between the individual components of the IVF cycle will assist when trouble-shooting possible problems in a laboratory which could have an adverse effect on cycle outcome. This article will review handling of oocytes and embryo culture, preparation of gametes for insemination and microinjection, selection of the most viable gametes and embryos, cryopreservation, and successful embryo transfer from the laboratory perspective.

Sexual reproduction and seasonality of the Alaskan red tree coral, Primnoa pacifica.

The red tree coral Primnoa pacifica is an important habitat forming octocoral in North Pacific waters. Given the prominence of this species in shelf and upper slope areas of the Gulf of Alaska where fishing disturbance can be high, it may be able to sustain healthy populations through adaptive reproductive processes. This study was designed to test this hypothesis, examining reproductive mode, seasonality and fecundity in both undamaged and simulated damaged colonies over the course of 16 months using a deepwater-emerged population in Tracy Arm Fjord. Females within the population developed asynchronously, though males showed trends of synchronicity, with production of immature spermatocysts heightened in December/January and maturation of gametes in the fall months. Periodicity of individuals varied from a single year reproductive event to some individuals taking more than the 16 months sampled to produce viable gametes. Multiple stages of gametes occurred in polyps of the same colony during most sampling periods. Mean oocyte size ranged from 50 to 200 µm in any season, and maximum oocyte size (802 µm) suggests a lecithotrophic larva. No brooding larvae were found during this study, though unfertilized oocytes were found adhered to the outside of polyps, where they are presumably fertilized. This species demonstrated size-dependent reproduction, with gametes first forming in colonies over 42-cm length, and steady oocyte sizes being achieved after reaching 80-cm in length. The average fecundity was 86 (±12) total oocytes per polyp, and 17 (±12) potential per polyp fecundity. Sub-lethal injury by removing 21–40% of colony tissue had no significant reproductive response in males or females over the course of this study, except for a corresponding loss in overall colony fecundity. The reproductive patterns and long gamete generation times observed in this study indicate that recruitment events are likely to be highly sporadic in this species increasing its vulnerability to anthropogenic disturbances.

Personalized treatment of infertility – way to increase treatment efficiency

Objectives To overcome the still not sufficient implantation rate following in vitro fertilization (IVF) and intracytoplasmatic sperm injection (ICSI) in humans, more than two embryos are commonly replaced, potentially leading to high number of multiple pregnancies with associated significantly elevated risks like low birth weight. One of the solutions for avoiding multiple pregnancies could be optimalization of embryo selection and single embryo transfer [1]. The traditional systems for assessing gamete and embryo viability have limited ability to accurately select those with best developmental potential. Morphological evaluation remains the primary method of the oocyte and embryo assessment during IVF cycles, but its modest predictive power and inherent inter- and intra-observer variability limits its value. Prolonged embryo culture to blastocyst stage was introduced as a possible strategy for selecting the best embryos, though not even this method brought the solution. The extended period of in-vitro culture may have its side effects – e.g. predispose the embryo to phenomena such as ‘large offspring syndrome’, which is probably linked to altered gene expression, particularly of imprinted genes. The unexplained repeated implantation failure (RIF) is still another unsolved and one of the principal problems to affect the outcome of assisted reproductive technology (ART). The successful embryo implantation requires accurate temporal regulation of maternal immune function (to accommodate a semi-allogeneic embryo) and endocrine system [2]. The past few years have witnessed a virtual explosion in the identification of gene mutations or polymorphisms that cause or are linked to human infertility and that are inherited in a polygenic/ multifactorial fashion. Suggested technologic approaches The “best viable” embryo selection and also the optimal implantation regulation, both are going to be solved by new diagnostics and treatment methods based on personalized omics profiling [3]. Molecules of embryo-endometrial cross talk that are engaged in regulation of the embryo implantation and selected components of follicular fluid as well as embryo media will play a role on a developmental potential of the embryo and treatment efficiency. Expected impact if the project will succeed The goal of our effort is to point out new and potentially useful biomarkers that can be used for the improvement of pregnancy rates after the assisted reproduction techniques (ART) in near future and also to emphasize some of the novel molecular targets and biomarkers that have been reported recently and might contribute to new strategies of infertility management that will return a hope of natural conception for selected couples. Evaluation of such markers may help clinicians to predict pregnancy outcome and detect occult implantation deficiency. Moreover, these novel molecular targets are expected to apply to the clinical practice from bench to bedside and improve the implantation efficiency in ART.

Somatic cells, stem cells, and induced pluripotent stem cells: how do they now contribute to conservation?

More than a decade has now passed since the birth of the first endangered species produced from an adult somatic cell reprogrammed by somatic cell nuclear transfer. At that time, advances made in domestic and laboratory animal species provided the necessary foundation for attempting cutting-edge technologies on threatened and endangered species. In addition to nuclear transfer, spermatogonial stem cell transplantation and induction of pluripotent stem cells have also been explored. Although many basic scientific questions have been answered and more than 30 wild species have been investigated, very few successes have been reported. The majority of studies document numerous obstacles that still need to be overcome to produce viable gametes or embryos for healthy offspring production. This chapter provides an overview of somatic cell and stem cell technologies in different taxa (mammals, fishes, birds, reptiles and amphibians) and evaluates the potential and impact of these approaches for animal species conservation.

Effects of triclosan on reproductive prarmeters and embryonic development of sea urchin, Strongylocentrotus nudus

Triclosan (TCS, 2,4,4′-trichloro-2′-hydroxydiphenyl ether), a broad-spectrum antibacterial agent, is commonly found in the aquatic environment. In this study, we investigated TCS toxicity with pertaining to gamete viability, fertilization, and embryogenesis up to pluteus stage of the sea urchin, (Strongylocentrotus nudus). When the sperm and eggs were exposed to TCS (0–3.0μM), the viability of sperm was significantly decreased at molarities higher than 1μM of TCS. In addition, for exposure of 2.0μM TCS the viability of eggs was not influenced and none of the sperm was viable. Fertilization rate was significantly decreased when sperm were exposed to 0.5 and 1μM of TCS (p<0.001) and no fertilization was observed for the exposure of 1.5μM of TCS. In embryonic development, embryos are treated with higher than 1.0μM levels of TCS displayed arrested development. For TCS, the EC50 and LOECs values were 1.8, 1.49 and 0.99μM and 0.53, 0.62 and 0.39μM for sperm viability, fertilization rate, and larval development to pluteus, respectively. In the recovery test regarding normal development of arrested embryos based upon TCS exposure time, it was observed that embryos exposed to 1μM TCS for 15h were normally recovered for normal development, while embryos with more than 30h exposure were not recovered to normal larvae. Overall, the results of this study strongly suggest that the gametes and embryos of S. nudus can provide the basis for an effective bioassay, with a fast and sensitive means of evaluating TCS contamination in the marine ecosystem.