Gonadal Development Cycle Research Articles

Cyclicity in ontogeny and age determination of Flexopecten glaber (Bivalvia, Pectinidae) in the Black Sea

Flexopecten glaber is an actively fished species in the Mediterranean Sea and a promising candidate for mariculture in the Black Sea. Flexopecten glaber is included in the Red Data Books of the Republic of Crimea and Sevastopol city as a species declining in number (Category 2). In this study, over 1500 specimens sampled near the Crimean Peninsula between 2017 and 2023 were analysed to investigate the ontogeny of F. glaber and develop a method for determining individual age, based on the relationship between stages of gonadal development and changes in shell surface morphology. The cyclicity of development was assessed by comparing the cycles of gonad formation with the features of the surface morphology of the shell. A correlation was found between the morphology of the surface of shell valves and the stages of the annual cycle of gonad development. On this basis, a scheme for determining the developmental stages and individual age of F. glaber specimens from the morphology of shell valves has been developed. The most prominent mark on the shell surface is formed mainly in winter as a result of the physiological restructuring of the organism before the beginning of the annual cycle of gonad formation. However, to determine the age of F. glaber, the spawning marks formed mainly in summer need to be considered. The proposed scheme for determining the developmental stages and age of F. glaber individuals is a valuable tool for studying the species and can help resolve a variety of ecological and conservation issues.

From west to east: Heterogeneity in the life history traits of a small pelagic fish (Sardina pilchardus) throughout the Mediterranean

Small pelagic fish are key elements of marine trophic networks and are of great importance to the total landing of marine species. Over the last decades, a decrease in biomass and catches of European sardine has been described, especially in the Mediterranean Sea, as an indication of a drop in stock condition. Multiple causes, including direct and indirect anthropogenic factors, seem to affect this ecologically and economically important species. To address this issue, it is important to identify the current variability in sardine status and understand the strategies for energy allocation, which are intimately related to reproductive potential and recruitment. We analyzed the somatic condition through tissue and mesenteric lipid measurements, relative condition (Kn) and hepatosomatic (HSI) indices, and reproductive condition with the gonadosomatic index (GSI) in four subareas of the Mediterranean (Northern Alboran, Northern Spain, the Northern Adriatic, and the Aegean Sea) and an outgroup from the Atlantic. The analyses were performed within the gonadal development cycle since translocation to reproduction may mask the state of actual energy reserves for comparison. The results revealed marked differences in health status among subareas, highlighting the low condition of Northern Spain sardines throughout the annual cycle. The uniform condition throughout gonadal development in the Northern Adriatic suggests that resource availability modulates the reproductive strategy since in this locality, sardines would have high dependence on immediate reserves, not behaving as strict capital breeders. Moreover, similarities between Alboran and Atlantic stocks are discussed, highlighting the marked energy replenishment of the latter after reproduction compared to the Mediterranean stocks. The Aegean stock was the fastest to reach its maximum after spawning, presenting low condition values from the developing to actively spawning period, but with the greatest recovery at the regressing phase, coinciding with a peak in productivity. Finally, the role of the liver in sardine energy storage is analyzed considering stock heterogeneity, potentially indicating that HSI is intimately related to feeding activity. Given the divergences among stocks, we propose concrete measures for managing this resource (i.e., the need for adapting the close seasons), which could be applied to other species in similar contexts.

Annual reproductive cycle of a successful Lessepsian immigrant in the Eastern Mediterranean Sea, Pomadasys stridens (Forsskål, 1775) (Family: Haemulidae)

ABSTRACT The striped piggy, Pomadasys stridens (Forsskål, 1775), is one of the successfully colonized Lessepsian immigrants entering the Mediterranean through the Suez Canal. This study was carried out to understand to what extent the reproduction strategy adopted by this species had played a role in its successful establishment. The study is based on samples collected during the monthly trawl surveys conducted between January 2017 to November 2020 in the Northeast Mediterranean. The annual gonadal development cycle was estimated by observing the Gonadosomatic Index changes. Seasonal patterns in energy intake and allocation were acquired from Hepatosomatic, Digestosomatic, and Relative Body Condition indices. The results indicated that the species has prolonged gonadal development periods, during which spawning occurs twice, in early summer and at the onset of the winter. A comparison of all indices involved indicated that the species feeds and develops gonads at the same time before summer spawning, feeds heavily and stores energy during the warmest period, and uses the stored energy in the winter spawning. As these features do not differ much from their congenerics inhabiting the geography they originated from, it is suggested that it was not the ecological plasticity of the species that is the basis of their success but the reproductive traits they have fitted well to the Mediterranean Ecosystem.

Intra‐annual changes in reproductive indices of male and female Himalayan snow trout,Schizothorax richardsonii(Gray, 1832)

Periodic changes in reproductive hormone levels, gonadal histology and gonadosomatic index (GSI) of snow trout, Schizothorax richardsonii, were examined to ascertain annual cycle of gonadal development and reproductive status in their natural habitat. In females, there were coherent changes in plasma 17β-oestradiol and vitellogenin along with GSI, oocyte maturation and vitellogenic progression, collectively indicating two distinct maturation peaks during the months of September and February. Coinciding with this, in males, plasma 11-keto testosterone was also noticeably higher during September and February, with highest GSI values in September. However, plasma 17α, 20β-dihydroxyprogesterone levels in males were found to be persistently high from September to February. This observation suggests the potential presence of matured oozing males over a longer period, unlike in females. Overall, the close association between reproductive hormone levels, GSI and gonadal maturation stages in males and females (particularly, the presence of postovulatory follicle complexes) with apparent natural synchronization clearly indicates that S. richardsonii breeds twice in a year, possibly during late September to early November and late February to early April in the coldwater riverine habitats of the Indian Himalayan region.

The Annual Reproductive Cycle of Rudd, Scardinius erythrophthalmus (Cyprinidae) from the Lower Oder River and Lake Dąbie, (NW Poland)

The rudd is a common freshwater species of the European ichthyofauna, however, this species' sexual cycle has not yet been described based on the histological analysis of its gonads. The aim of this study was to analyze the annual gonad development cycle of rudd from the watercourses of north-western Poland. Adult individuals aged 2+ to 13+, of both sexes were caught in the Oder River and Lake Dąbie. A standard paraffin technique and six-stage scales were used to assess the development of gonad maturity in both sexes. Rudd gonads developed similarly in the Oder River and Lake Dąbie. Eggs were deposited in batches from the beginning of May to the half of June. Females deposited at least two batches of eggs. In the majority of females collected from these sites, the gonads developed asynchronously throughout the year. Rudd males attained reproductive readiness in the same period as the females, but retained gametes in their gonads for a month longer than the females. Rudd avoid locations with warmer water discharged from power plants.

Reproductive biology of the southern pufferfish, Sphoeroides nephelus (Actinopterygii: Tetraodontiformes: Tetraodontidae), in the northern coast off the Yucatan Peninsula, Mexico

Background. Overexploitation of fishery resources has led to the capture of alternative species of a lower trophic level, considered previously unprofitable or unfit for human consumption. The southern pufferfish, Sphoeroides nephelus (Goode et Bean, 1882), is a bycatch species of the recreational fishery in the USA and Mexico. Unlike other species of the genus Sphoeroides, there is no background on their reproductive cycle. Therefore, this study aimed to describe several reproductive traits (sex ratio, gonadal development, annual reproductive cycle, and fecundity) of specimens from the northern coast of the Yucatan Peninsula, Mexico. This kind of information might serve as a point of reference for its potential use either in the pharmaceutical industry, aquarium trade, as well as in aquaculture. Materials and methods. The reproductive biology of the southern pufferfish was described based on 189 females and 223 males, caught off the northern coast off the Yucatan, Mexico, during an annual cycle. Several reproductive traits, such as the annual cycle of gonad development, sex ratio, and the batch fecundity were determined. Results. The sex ratio showed no significant difference from 1 ÷ 1 ratio. Male’s reproductive season lasted from August to May, although females were spawning from August to April. The size at 50% maturity was estimated at 14.93 cm TL for females. Batch fecundity ranged between 59 087 and 367 022 oocytes (mean 176 456) per spawning batch, and it was significantly fitted to both female size and weight based on power and linear regression models, respectively. The relative batch fecundity was estimated at 828 ± 182 oocytes per gram of eviscerated weight, and 11 989 ± 4774 oocytes per gram of gonad weight. Conclusion. It was determined that S. nephelus exhibited 1 ÷ 1 sex ratio, an asynchronous development of oocytes and indeterminate fecundity with batch spawning. The species has a protracted reproductive season that lasted almost all year round with peaks in February–March (before of the dry season) and a brief inactive period in June–July (before of the wet season). This latter information should be helpful to obtain a broodstock that would be the base to produce fingerlings to be raised, instead of collecting individuals from the wild.

Determining the biological zero for gonadal development razor clams Sinonovacula constricta (lamarck 1818) in Zhejiang, China

The biological zero of gonadal development and the effective accumulated temperature of one and two-year-old razor clams Sinonovacula constricta (Lamarck 1818) were studied in Sanmen County, Zhejiang Province, China between April 2016 to October 2017, using a new variety named “Shen-Zhe No. 1”. The biological zero was determined by using the rule of effective accumulated temperature and the linear regression method, which was confirmed using a histological analysis of the full gonadal development cycle. The results showed that the biological zero of gonadal reproduction of 1-year-old and 2-year-old S. constricta was the same: 20.8 °C. When the temperature reached 20–21 °C, analysis of the histological sections indicated that more than half of the S. constricta individuals initiated gonadal development. The average effective accumulated temperature over two years was 806 d °C. This study contributes to our understanding of the regulation and control of gonadal maturation, suggesting that changes in the spawning and breeding season during one-year of farming using the new variety of razor clam could provide an economic benefit to industrialized large-scale spat production. The results demonstrated that the razor clam S. constricta is a typical clam of the accumulative temperature mature oviposition type. In addition, although S. constricta does not display hypothermy, it requires a lower temperature for gonadal maturity and spawning.

Reproductive patterns of the black starry sea urchin Arbacia stellata in Punta Banda, Baja California, Mexico

AbstractWidely distributed species such asArbacia stellataadjust patterns of their life history according to local conditions. In the present study the reproductive cycle of this species was analysed throughout a sampling year. Gonadal development cycle, sex ratio, actual fecundity and oocyte size distribution were characterized and the relationship of these reproductive characteristics with environmental variables such as sea surface temperature, photoperiod, chlorophyllaand net primary production evaluated. Our results showed thatA. stellatais a gonochoric sea urchin. Gametogenesis was classified into six stages for both sexes (immature, growth, pre-maturity I, pre-maturity II, mature and spawning) and no synchrony was observed for the gonads between individuals. The female to male ratio was close to 1:1 in most months. The gonadosomatic index (GSI) showed significant differences between sexes or months; however, the highest values were observed during spring, with positive correlation with chlorophylla. No significant differences were observed in the maturity index (MI) between sexes, with a positive correlation with temperature but negative with chlorophyll. Actual fecundity showed wide variations throughout the year and correlation with chlorophyllaand temperature. Oocyte size distribution was unimodal and the predominant frequency was that of mature oocytes. The reproductive cycle ofA. stellatahas a semi-continuous pattern for both sexes and partial spawning throughout the year in the sampling site. We observed nutrient assimilation in the gonads during spring and a larger reproductive activity from late summer to early winter.

Minor Splicing Factors Zrsr1 and Zrsr2 Essential for Gametogenesis, Early Embryo Development and Conversion of Stem Cells into 2C-Like

Zrsr2 has been attributed a role in splice site recognition of U12 and U2 introns. To better understand the part played by minor splicing during oogenesis and early embryo development, we produced Zrsr2 mutant mice (Zrsr2mu). In Zrsr2mu female oogenesis was blocked at the secondary follicle stage, in a similar way as Zrsr1mu affects spermatogenesis. Zrsr2mu follicles showed altered expression of genes related to gonad development, DNA replication and cell cycle regulation, and altered splicing events involving enrichment of U12-type intron retention (IR). Embryo development was impaired during zygotic gene activation (ZGA) at the 2-cell stage when female Zrsr2mu were crossed with male Zrsr1mu. These embryos showed increased IR in U12-containing genes related to the cell cycle and mitotic nuclear division. Remarkably, both mouse Zrsr1 and Zrsr2 were required for conversion of mouse induced pluripotent stem cells (iPSC) into 2C-like cells. According to our results, Zrsr1 and Zrsr2 are essential during overall chromatin reorganization in the meiotic prophase of meiosis, ZGA and conversion of pluripotent into 2C-like cells.

Scotostimulation of reproductive neural pathways and gonadal maturation are not correlated with hypothalamic expression of deiodinases in subtropical spotted munia.

Circannual rhythm regulates the annual timing of reproduction in spotted munia, with sex differences in its relationship with the external photoperiod environment. Interestingly, munia show an atypical photosensitivity and exhibit gonadal maturation when acutely exposed to an unnatural short photoperiod (eg 3hours of light per day; ie a long scotoperiod). The proximate mechanisms regulating scotoperiod-induced hypothalamic-pituitary-gonadal (HPG) activation are unclear. Because thyroid hormone signalling plays a central role in photoperiodic induction, we hypothesised the involvement of similar mechanism, comprising alterations in hypothalamic deiodinases, under long scotoperiod-induced HPG activation. To test this, several endpoints of cellular and molecular correlates were assayed in male and female munias after 1 and 4 weeks of exposure to an 3:21hour light/dark cycle (3L:21D), with controls on a 21:3hour light/dark cycle (21L:3D). We measured the hypothalamic expression of mRNA and protein of light-sensitive (neuropsin, OPN5) and reproductive (vasoactive intestinal peptide [VIP], neuropeptide Y [NPY], gonadotrophin-releasing hormone [GnRH], gonadotrophin-inhibiting hormone [GnIH]) neuropeptides by quantitative polymerase chain reaction (PCR) and immunohistochemistry, respectively. In addition, we also measured mRNA expression of types 2 (DIO2) and 3 (DIO3) deiodinases that regulate triiodothyronine-mediated GnRH release and gonadal maturation in photoperiodic species. The quantitative PCR and immunohistochemistry results were consistent. Higher OPN5 levels under 21L:3D than under 3L:21D suggested its role in sensing the length of the light period. Similarly, low VIP and high NPY expression under 3L:21D than under 21L:3D were consistent with their roles as cellular correlates of photic and nonphotic environment, respectively. High GnRH-I/low GnIH levels and gonadal recrudescence under 3L:21D, and an inverse pattern under 21L:3D, confirmed the scotostimulation of HPG axis in spotted munia. However, DIO2 and DIO3 mRNA levels did not differ between 2 scotoperiods, in contrast to their reciprocal expression pattern found during long-day photostimulation. We demonstrate for the first time sex-dependent scotostimulation of reproductive neural pathways and suggest the involvement of molecules other than hypothalamic deiodinases in the regulation of gonad development cycle in 'nonphotoperiodic' seasonally breeding vertebrates.

Elevated Expression of follistatin Gene in the Pituitaries of Allotriploid Crucian Carp

AbstractAs a paracrine factor, Follistatin (Fst) plays an important role in regulating biosynthesis and release of pituitary gonadotropin (GTH), gonadal development, and ovulation cycle. In this study, full‐length complementary DNAs (cDNAs) of the follistatin gene in diploid red crucian carp, Carassius auratus red var., allotriploid crucian carp, and allotetraploid hybrids were obtained. Our data showed that the cDNAs of follistatin of all three fish encoded 322 amino acids. Referring to the structural characteristics of Fst in other species, we found that the Fst protein of these three fish had four domains, respectively. Reverse transcriptase polymerase chain reaction (PCR) indicated that the follistatin gene was widely expressed in all tested tissues, except spleens, in these three fish. Real‐time quantitative PCR analysis of different seasonal profiles showed that allotriploids had significantly higher expression of follistatin messenger RNA in pituitaries during both the prespawning and spawning periods. These results suggest that the elevated expression of the follistatin gene in the pituitaries of allotriploids might lead to sterility of allotriploids by blocking the inhibitory effect of activin on luteinizing hormone β subunit. Furthermore, the results may improve our understanding of reproduction characteristics in triploids, which benefits polyploidy breeding.

Histological study of annual cycle of gonad and germ cell development of Whitmania pigra

The reproductive system and gonad development and germ cell occurrence of Whitmania pigra have been studied by using tissue section electron microscope techniques. W. pigra has completely independent male and female reproduction system, which lasts 11 months. The development of spermary started before the development of ovary. When egg cell is only a primordial germ cell, sperm has an initially complete form. Meanwhile, sperm cells and egg cells orderly development and synchronously mature. According to the development of sperm cells and egg cells, the development of cycle of the spermary could be divided into 6 stages: proliferating stage (1-3 months of age), growing stage (4-5 months of age), resting stage (6-8 months of age), maturing stage (9 months of age), spawning stage (10 months of age) and degradation stage (11 months of age). The development of cycle of the ovary could be divided into 6 stages: forming stage (1-2 months of age), proliferating stage (3-4 months of age), growing stage (5-8 months of age), maturing stage (9 months of age), spawning stage (10 months of age) and resting stage (11 months of age). W. pigra is a synchronous hermaphrodite animal, the development of cycle of the spermary and ovary each has six stages, sperm cells and egg cells orderly development and synchronously mature.

Molecular cloning, characterization and expression profile of kisspeptin1 and kisspeptin1 receptor at brain-pituitary-gonad (BPG) axis of golden mahseer, Tor putitora (Hamilton, 1822) during gonadal development.

Complete cDNA sequences of kiss1 (gmkiss1) and its receptor kiss1r (gmkiss1r) were cloned and characterized from brain tissue of adult golden mahseer (Tor putitora). Thereafter, quantification of gmkiss1 and gmkiss1r mRNA expression in brain-pituitary-gonad (BPG) axis of male and female golden mahseer was carried out using quantitative real-time (qRT)-PCR assay during an annual reproductive cycle, at different gonadal development stages. The gmkiss1 cDNA was 508bp, with 330bp open reading frame (ORF), encoding a precursor protein of 109 amino acids, whereas gmkiss1r cDNA was 1383bp with an ORF of 1004bp, which encodes a 334 amino acid protein residue. The qRT-PCR study shows that gmkiss1 and gmkiss1r are expressed in brain, pituitary and gonads of both the sexes of golden mahseer. An apparent sexual dimorphism in transcript level of gmkiss1 and gmkiss1r in brain and gonads was evident during the reproductive cycle. Overall, in brain, testis and ovary, the gmkiss1 and gmkiss1r mRNA expression level was comparatively higher during the initial stages of gonadal development, than that of spermiation or ovulation stage. In pituitary of both the sexes, throughout the gonadal development, consistently low transcript level of gmkiss1 and gmkiss1r was observed. The gmkiss1 mRNA expression level in brain and ovary of female golden mahseer was several folds higher than the brain and testis of male fish. In conclusion, we confirm the presence of kiss1 and its receptor in golden mahseer, and results of our study strongly suggested the involvement of kisspeptin1 system in gonadal development and annual reproductive cycle of this species.

Gonadal Development and Reproductive Cycle of Cultured Abalone,Haliotis discus hannai(Gastropoda: Haliotidae) in Korea: Implications for Seed Production

The objective of this study was to examine gonad development and reproductive cycle of the abalone Haliotis discus hannai at three main abalone aquaculture farms (Uljin, Wando, and Jeju Island) in Korea to obtain information on artificial seed production. The sex ratio (female:male) was approximately 1:1 without significant difference among the three regions or between females and males. Average gonad index was the highest during July in Uljin and Jeju Island and during August in Wando. There was no definitive seasonal change in condition index and meat weight index throughout the year in the three regions. The gonad of H. discus hannai displayed seasonal change histologically, thereby enabling us to distinguish the following stages: inactive (November–December), early active (January–March), late active (March–April), ripe (May–July), spent (August–October), and degenerative (October–November). The main spawning period of H. discus hannai was determined to be during September–October in Uljin and Wando, and August–September in Jeju Island.

Synchronous Reproduction in Mussel (Mytilus Galloprovincialis) Population from Atlantic Ocean of Morocco

We investigated the gametogenesis of a natural population of Mytilusgalloprovincialis in the Atlantic central zone (Cape Beddouza). We found that the cycle of reproduction was characterized by a synchronous gametogenesis. From March 2009 to March 2011, we histologically analyzed the status of gonad development and the reserves cells at the peak of spawning. To determine the status of gonad development, we used three biological indecies parameters: the gonadic index, the condition index and the ADG index. The gonadic index was the highest in winter. The condition index was the lowest in spring. The ADG index was the highest in autumn. We found synchrony of these indices in majority of sampled M. galloprovincialis. The found synchrony was unique in the populations other waters in Moroccan coast, where gonad development cycle was individually different. The synchrony of reproductive cycle in the population maybe a result of the consistent seasonal pattern of environmental variable along the cape.

Annual development cycle of gonads of bream (Abramis brama L. 1758) females from the lower Oder River sections influenced differently by the heated effluents from a power station

Gonads of female bream from three locations with varied temperature-influenced water from power plant cooling water effluents were analysed: (i) from the Oder River (above Gryfino, with no influence of the post-cooling water effluents from the ‘Dolna Odra’ power plant, NW Poland), (ii) from Lake Dąbie, below the canal receiving the heated effluents from the power station, and (iii) from downstream the effluent canal. Histological analysis indicated that in ambient conditions, the spawning season began at the study sites at the end of April and lasted through May and part of June. The initiation of gonad restoration (beginning of vitellogenesis, stage 3) was observed at the end of July, both in the Oder River and Lake Dąbie, and lasted throughout September. The gonads were at stage 4 in males from October to April and, in a few females, to May. The annual cycle of gonad development was similar in the female bream from both sites. The microscopic images of the oocytes were in the previtellogenesis and vitellogenesis at the two sites. The maximum diameter of the oocytes from the Oder was 909.7 μm, while oocyte diameter of fish from Lake Dąbie was 1018.4 μm. Oocytes not expelled during spawning season (May to August) were seen to undergo atresia. Female gonads from the heated effluent canal did not show any anomalies and the oocytes from the few fish caught in the winter were similar to those from the breams in other locations. Adult bream avoided excessive temperatures in the power plant effluent canal in the spring and summer, whereas juveniles were found in great numbers. In the spring, no female bream with mature gonads were caught in the cooling water effluent canal.

한국산 둥근전복, Haliotis discus discus의 생식주기

ABSTRACT This study histologically describes the gonadal development and reproductive cycle of the abalone, Haliotis discus discus inhabiting Jeju Island of Korea. Gonads displayed histologically definitive seasonal changes. The gonad index (GI) of both females and males was the highest (3.2 and 3.3) in September and was the lowest (1.7 and 1.4) in January and February. Egg diameter increase from early stage in March and reach about 180 μm to ripe stage in August. The condition index (CI) was highest in July and lowest in May. The pattern of changes in the GI, egg diameter and CI were similar to the pattern of seasonal changes in gonadal tissues. The female ratio (F/F + M) was 59% (n = 182:127). The reproductive cycle was divided into an inactive stage (January-February), early active stage (March-April), late active stage (May–July), ripe stage (August–October) and spent and degenerative stage (November-January). The main spawning period of H. discus discus was August to October at Jeju Island in 2014. Keywords:

Molecular cloning and expression analysis of dmrt1 and sox9 during gonad development and male reproductive cycle in the lambari fish, Astyanax altiparanae.

BackgroundThe dmrt1 and sox9 genes have a well conserved function related to testis formation in vertebrates, and the group of fish presents a great diversity of species and reproductive mechanisms. The lambari fish (Astyanax altiparanae) is an important Neotropical species, where studies on molecular level of sex determination and gonad maturation are scarce.MethodsHere, we employed molecular cloning techniques to analyze the cDNA sequences of the dmrt1 and sox9 genes, and describe the expression pattern of those genes during development and the male reproductive cycle by qRT-PCR, and related to histology of the gonad.ResultsPhylogenetic analyses of predicted amino acid sequences of dmrt1 and sox9 clustered A. altiparanae in the Ostariophysi group, which is consistent with the morphological phylogeny of this species. Studies of the gonad development revealed that ovary formation occurred at 58 days after hatching (dah), 2 weeks earlier than testis formation. Expression studies of sox9 and dmrt1 in different tissues of adult males and females and during development revealed specific expression in the testis, indicating that both genes also have a male-specific role in the adult. During the period of gonad sex differentiation, dmrt1 seems to have a more significant role than sox9. During the male reproductive cycle dmrt1 and sox9 are down-regulated after spermiation, indicating a role of these genes in spermatogenesis.ConclusionsFor the first time the dmrt1 and sox9 were cloned in a Characiformes species. We show that both genes have a conserved structure and expression, evidencing their role in sex determination, sex differentiation and the male reproductive cycle in A. altiparanae. These findings contribute to a better understanding of the molecular mechanisms of sex determination and differentiation in fish.

한국 진도에서 채집된 북방전복, Haliotis discus hannai의 생식주기

ABSTRACT This study histologically describes the gonadal development and reproductive cycle of the abalone, Haliotis discus hannai inhabiting Jindo on the southern seashores of Korea. Gonads displayed histologically definitive seasonal changes. The female ratio (F/F + M) was 57% (n = 154/271). The gonad index (GI) of both males and females was the highest (3.3 and 3.9) in June and was the lowest (1.1 and 1.1) in December. The condition index (CI) and meat weight rate (MWR) were highest in May and lowest in October. The pattern of changes in the GI, CI and MWR were similar to the pattern of seasonal changes in gonadal tissues. The reproductive cycle was divided into an inactive stage (November–December), early active stage (January–March), late active stage (March–April), ripe stage (May–June) and spent and degenerative stage (July–October). The main spawning period of Haliotis discus hannai was July to August at Jindo in 2013. Keywords: Haliotis discus hannai , reproductive cycle, main spawning period

Annual development of gonads of pumpkinseed, Lepomis gibbosus (Actinopterygii: Perciformes: Centrarchidae) from a heated-water discharge canal of a power plant in the lower stretch of the Oder River, Poland

Background. The pumpkinseed, Lepomis gibbosus (Linnaeus, 1758), known also as pumpkinseed sunfish, is native to eastern and central North America. Its introduction to Europe has resulted in fast spreading of the species over the continent. In Poland, the pumpkinseed has found favourable conditions for living and reproduction in water bodies artificially heated by thermal power plants. The aim of this study was to determine the annual cycle of gonad development of the pumpkinseed population inhabiting the warm-water canal of the Dolna Odra power plant (NW Poland), which has not been studied before at this location. Materials and methods. The pumpkinseed individuals were caught in the heated-water discharge canal of the Dolna Odra power plant. The average water temperature in the canal was by 6–8ºC higher than that of the river. The analysis of the annual cycle of gonad development was performed in both sexes using histological methods. The fish were aged 3+ to 6+. A standard paraffin technique and Heidenhain’s iron hematoxylin staining were used. Results. In the site surveyed, the spawning season for females lasted from the beginning of May through August, i.e., was longer than in the native range of this fish species. In one female caught in September, the ovaries contained oocytes in the stage of vitellogenesis. The oocytes in the stage of atresia were found rarely in the fish caught from April through June. Mature testes in males were found between late April and September, i.e., throughout the spawning period of the females. Few male anomalies of the sexual cycle were observed, e.g., in October, they were found to engage in another cycle of spermatogenesis and spermatozoa production. Moreover, the presence of large groups of degenerating cells in the seminal tubules was observed throughout the year, but was particularly evident between September and February. Conclusion. The results have confirmed the high colonisation abilities of the pumpkinseed. As a consequence of global warming, the studied canal with post-cooling water may become a starting point of expansion of this species to other bodies of water. Upon a considerable climate warming, this species could threaten the native species.