Effect of salinity on growth and first sexual maturity of Exopalaemon carinicauda(Holthuis, 1950)

To determine the optimal salinity for growth and first sexual maturity of ExopaIaemon carinicauda, the effects of salinity on growth and reproductive performance of early juvenile prawns of E. carinicauda were evaluated under laboratory conditions. Postlarvae from the same female broodstock were reared at six salinity levels （5, 10, 15, 20, 25, and 30） for 12 weeks. The specific growth rate （SGR） and survival rate （SR） under different salinity levels in the first 6 weeks were calculated and compared. SGR was significantly influenced by salinity. Prawns reared in salinity of 10 grew significantly faster （P〈0.05） than those reared in salinities of 5, 20, 25, and 30. However, ANOVA confirmed that there was no significant effect among the six salinity levels on SR. For the next 6 weeks, the body length （BL）, body weight （BW） at the first sexual maturity, and the age at median sexual maturity （As0） of females were measured and compared. Female prawns reared at salinity of 10 presented significantly shorter A50, but no significant differences among the six salinity levels for BL and BW at the first sexual maturity were observed. Based on the above information, the optimal salinity for growth and first sexual maturity of juvenile E. carinicauda is approximately 10.

Effects of Panax ginseng,Codonopsis pilosula and Pseudostellaria heterophylla on Sexual Maturity of SD Female Rats

[Objectives] To study the effects of Panax ginseng,Codonopsis pilosula and Pseudostellaria heterophylla on the growth and development of SD female rats. [Methods] The rats were randomly divided into control group,P. ginseng group,C. pilosula group,and P. heterophylla group,intragastrically administered with physiological saline,P. ginseng,C. pilosula,and P. heterophylla for 2 weeks,daily vaginal smear inspection was performed,estradiol( E_2) level before and after intervention was detected,rats were dissected,took out ovary and uterus,and calculated the ovarian index and uterus index. [Results]In 4 groups of rats,there was no significant difference in the time of sexual maturity and ovarian index; compared with the control group,E_2 level of C. pilosula group and P. ginseng group were higher( P < 0. 05);compared with the control group and P. heterophylla group,the ovarian index of P. ginseng group was higher( P < 0. 05); compared with the control group,the body weight of three administration groups increased much more( P < 0. 05). [Conclusions] P. ginseng and C. pilosula may lead to sexual maturity of SD female rats,while P. ginseng,C. pilosula and P. heterophylla can promote increase of body weight of SD female rats.

Gametogenic Cycle, the Spawning Season, First Sexual Maturity, and the Biological Minimum Size in Male Ruditapes philippinarum （Bivalvia： Veneridae） in Western Korea

The male gametogenic cycle, spawning season, first sexual maturity, and the biological minimum size in male Ruditapes philippinarum were investigated by qualitative and quantitative reproductive analyses. In the study of the male gametogenic cycle by qualitative histological analysis, the gametogenic cycle in male individuals can be classified into five successive stages： （1） early active stage, （2） late active stage, （3） ripe stage, （4） partially spawned stage, and （5） spent and inactive stage. Monthly changes in the gonad index in males measured by qualitative analysis showed a similar pattern to the male gametogenic cycle. In the study of the male gametogenic cycle by quantitative statistical analysis, monthly changes in the portions （%） of areas occupied by the testis areas to total tissue areas showed a rapid increase in March, and reached the maximum in May-June. And also monthly changes in the portions （%） of areas occupied by the spermatogenic stages to the testis area showed a maximum in May and gradually decreased from June to October. Therefore, this species showed a unimodal gametogenic cycle during the year, and the number of spawning seasons occurred once per year, from June to October, with a peak spawning between July and August. The percentage at the first sexual maturity of male clams ranging from 15.1-20.0 mm in shell length was 64.7%, and that of all individuals ranging from over 25.1 mm in shell length was 100%. The biological minimum size （shell lengths at 50% of sexual maturity （RMs0）） of male mature clams that was fitted to an exponential equation was 17.16 mm （considered to be 1 year old）. Because harvesting clams less than 17.16 mm in shell length could potentially cause a drastic reduction in recruitment, a measure indicating a prohibitory fishing size should be enacted for adequate fisheries management.

Spatial variation in bigeye tuna Thunnus obesus size at sexual maturity in the eastern Pacific Ocean

Understanding the reproductive characteristics of a species is of crucial for accurate stock assessment and management plans to ensure sustainable fisheries.In this study,the size at 50%sexual maturity(L50)parameters in different bio-ecological provinces were estimated for bigeye tuna,Thunnus obesus,sampled from the Eastern Pacific Ocean tuna fisheries-dependent survey from 2013 to 2019.The overall sex ratio of the catch during the sampling differed significantly from 1:1.Bigeye tuna exhibit sexual dimorphism in the growth of males and females,with a clear shift in predominance from female to male with increasing sizes.In the North Pacific Sub-tropical Gyre(east)(NPST-east),North Pacific Tropical Gyre(NPTG),Pacific North Equatorial Countercurrent(PNEC),and Pacific Equatorial Divergence(PEQD),females(meals)reached sexual maturity round 102 cm(106 cm),106 cm(100 cm),125 cm(110 cm),and 113 cm(110 cm),respectively,the estimated L50 of bigeye tuna was 124.08 cm,121.97 cm,139.92 cm and 132.45 cm,respectively.The degree of populations mixing between equatorial(PNEC and PEQD)and high-latitude regions(NPST-east and NPTG)is extremely small,but it is reasonably high between the NPST-east and NPTG or PNEC and PEQD.These parameters were significantly different,suggesting the occurrence of a spatial difference in the size-at-maturity of bigeye tuna between these bio-ecological provinces.The findings of this study provide the key information for understanding the life history of bigeye tuna in the Eastern Pacific Ocean and will contribute to the conservation and sustainable yield of this species.

Dormancy and the influence of photoperiod and temperature on sexual maturity in Nicrophorus nepalensis （Coleoptera： Silphidae）

Carrion beetles （Nicrophorus spp.） use small vertebrate carcasses for food and reproduction. Their ecology and behaviors are highly affected by the availability of carcasses and the surrounding environmental conditions. Our results revealed that in subtropical Fushan, northern Taiwan, N. nepalensis was mainly active in spring （February to May）, and could also be found in autumn （October and November）; but there was no capture record in summer （June to September） and winter （December and January）. A laboratory temperature tolerance study indicated that N. nepalensis adults become inactive at temperatures above 26℃, and had the highest mortality when the temperature was raised from 27℃ to 28℃. Furthermore, N. nepalensis became sexually mature at 20℃, depending on the photoperiod： the longer the day, the lower the percentage of sexually mature 2-week-old females after emergence. In another experiment, N. nepalensis virgins were paired under three possible conditions at Fushan. At 15℃ and 20℃, if carcasses were presented to the pairs within 3 days after emergence, all laid eggs in the second week after emergence. If carcasses were presented 1 week after emergence, most began to reproduce at 20℃ with 12.5 h of daylight. However, at 15℃ with 1 l h of daylight, the carrion beetles hibernated first, and reproduced in the ninth week after emergence. At 25℃ with 14 h of daylight, carrion beetles did not bury the mouse carcasses, the females did not lay eggs, and the adult lifespan was only one-third of that at 20℃. This study revealed that both photoperiod and temperature influence the time needed to reach the sexual maturity of N. nepalensis; and also implied that the narrow temperature tolerance range and dormancy behavior of carrion beetles are highly regulated by those environmental factors.

Reproductive cycle,sexual maturity and fecundity of Nemipterus furcosus(Valenciennes,1830)

Understanding the reproductive biology particularly sexual maturity,reproductive cycle and fecundity of fish is useful for fisheries management.Unfortunately,there is no information about reproductive biology of Nemipterus furcosus.This study addresses this deficit for N.furcosus.We conducted a 12-month study to understand the reproductive biology particularly the sex ratio,sexual maturity,fecundity and reproductive cycle of N.furcosus at the east coast of peninsular Malaysia.Results indicated that ratios of male and female were statistically similar up to 19.0 cm TL(total length).Male outnumbered female above 19.0 cm TL(P<0.05).The fecundity ranged between 54,970 and 236,938 with a mean fecundity of 102,477±43,580(standard deviation).Male and female fish reached first sexual maturation at almost same size,15.8 and 15.6 cm,respectively.This information is needed to determine the lowest acceptable harvest length of this fish under the management aim to enter all female fish for reproduction minimum one time in their life.We estimated the reproductive period of N.furcosus applying oocytes diameter,histological examination of ovaries and monthly mean GSI.All of these methods gave a consistent result about spawning season,which appeared to be from March to July with peaks in March and June.Based on this result,N.furcosus spawners can be protected during March to July for entering the reproductive stock.Apart from artificial breeding,the results of this study might facilitate future efforts at fine-tuning fishing effort for a proper management of N.furcosus.

Sexual maturation in hens is not associated with increases in serum leptin and the expression of leptin receptor mRNA in hypothalamus

Background： In mammals, leptin is an attractive candidate for mediating the metabolic signal and the reproductive function via the specific receptor in hypothalamus. However, till now, the role of leptin on reproduction in birds is less well established. This experiment was conducted to elucidate the role of leptin on the onset of reproduction in bird, as a first step, to detect the changes of peripheral leptin and leptin receptor mRNA expression in hypothalamus between mature and immature hens at the same age. 120 ISA brown pullets at D60 were allocated randomly into two groups, long light （LL） group being raised under artificial light regimes with incrementally increased light phase （from 8 L：]6D to 14 L：]2D） and short light （SL） group raised on consistent light （8 L：16D） for 12 wk. Results： The results showed that pullets in LL group reached sexual maturation 15 d earlier than those in SL group. Serum E2 showed a significant increase with age, but no difference was observed between two groups. Serum leptin concentration decreased significantly from D112 to D136 in LL, and was markedly higher in LL group than that in SL at D112, while there was no significant difference between two groups at D136. Leptin receptor and GnRH-I mRNA expression in hypothalamus were significantly increased with age, yet there was no significant difference between SL and LL chickens at the same age. The expression of FSH-13 and LH-13 mRNA in pituitary was increased with age but did not show significant difference between LL and gland, and decreased from D112 to D136 in LL but not groups at the same age. SL group. GnfiH-I mRNA expression was very rich in pinea n SL group, and there was no difference between two Conclusions： These results indicate that the earlier sexual maturation in hens induced by long-light regime is not accompanied with an increase in serum leptin or leptin receptor gene expression in hypothalamus, or genes expression in HPG axis.

Effects of the Integrated TCM-WM Treatment of Nephrotic Syndrome on Growth and Sexual Development

Fifty children with nephrotic syndrome were treated by using herbal drugs for nourishing yin to reduce pathogenic fire, strengthening qi and tonifying the kidney, and promoting blood circulation and removing blood stasis in combination with glucocorticoid and immunodepressant. The body height, secondary sex characters, age of the first spermatorrhea for male and of menarche for female children, bone age measured with roentgenograms on the left wrist in 50 cases of the treatment group were compared with those in 31 cases of the control group treated by glucocorticoid and immunodepressant. The results showed that the delay of growth and sexual development as side-effects of glucocorticoid and immunodepressant were markedly reduced by the integrated TCM-WM treatment.

Breeding strategy of Acrossocheilus fasciatus in the Puxi Stream of the Huangshan Mountain

Breeding strategies of Acrossocheilus fasciatus were studied from 592 specimens collected monthly during May 2007 and April 2008 in the Puxi Stream of the Huangshan Mountain. Sex ratio of the studied population was 0.90 ： 1 （ ♀ ： ♂ ）, not significantly different from 1 ： 1. Both sexes reached their first sexual maturity at age 2 （the second calendar year of their birth）. Fifty percent of females and males reached maturity at a total length of 69.75 mm and 69.36 mm respectively, and the minimum total length was 61.54 mm and 58.96 mm, respectively. Based on the monthly changes in gonado-somatic index and egg- development process, the breeding season of the population was from May to August, with one obvious interval （in June） occurring in the breeding activity for the females. The nonsynchronous development of oocytes observed in mature ovaries indicated that A. fasciatus is a batch spawner. Absolute fecundity of A. fasciatus ranged from 308 to 2002 eggs with a mean of 857 eggs, increased significantly with total length, and was significantly different among three age groups. Relative fecundity ranged from 38.63 to 71.70 egg/g with a mean of 53.29 egg/g, and was not significantly different among the three age groups. It was suggested that these reproductive characteristics were adaptive strategies for A. fasciatus to acclimatize to lotic water where environmental factors were unstable but predictable [ Current Zoology 55 （5） ： 350 - 356, 2009].

Age Structure of Females in a Breeding Population of Echinotriton chinhaiensis(Caudata:Salamandridae) and Its Conservation Implication

Knowledge of life history is important for understanding possible connections to population declines. Here, we investigated the female age structure and fecundity of Echinotriton chinhaiensis, one of the most endangered salamanders in the world, using skeletochronology based on specimens collected in 2008 and 2009 from a population in Ruiyansi, northeast of Ningbo, Zhejiang, China. The results showed that most female salamanders were between 5 and 6 years of age, with the minimal reproductive age, predicted to be 3 years, and the clutch size correlated to the body size. We argue that both delayed attainment of sexual maturity and low fecundity make this species more vulnerable to extinction.

Age,growth and reproduction of Sarcocheilichthys nigripinnis from the Qingyi Stream in the Huangshan Mountains

Identifying the life-history strategies of fish and their associations with the surrounding environment is the basic foundation in the conservation and sustainable utilization of fish species.We examined the age,growth,and reproduction of Sarcocheilichthys nigripinnis using 352 specimens collected monthly from May 2009 to April 2010 in the Qingyi Stream.We found the sex ratio of this study population was 0.58:1(female:male),significantly different from expected 1:1.Females and males both comprised four age groups.The annuli on the scales were formed during February and March.No obvious between-sex difference was observed in length-weight and length-scale-radius relationships.The total length in back-calculation significantly increased with age for both sexes,but did not differ significantly at each age between the two sexes.An inflection point was observed in the growth curves given by the von Bertalanffy growth function for total weight.At this inflection point,fish were 3.95 years.Both sexes reach their 50% sex maturity at age 2,when females and males were 94.7 mm and 103.0 mm total length.The temporal pattern of the gonado-somatic index corresponded to a spawning period that occurred from April through July.The non-synchronicity of egg diameter in each mature ovary during the breeding period suggested these fish may be batch spawners.The absolute fecundity increased significantly with total length and weight,whereas no significant correlation was observed between the relative fecundity and body size.

A Review for Life-history Traits Variation in Frogs Especially for Anurans in China

Environmental variation can promote differentiation in life-history traits in species of anurans. Increased environmental stress usually results in larger age at sexual maturity, older mean age, longer longevity, slower growth, larger body size, and a shift in reproductive allocation from offspring quantity to quality, and a stronger trade-off between offspring size and number. However, previous studies have suggested that there are inconsistent geographical variations in life-history traits among anuran species in China. Hence, we here review the intraspecific patterns and differences in life-history traits（i.e., egg size, clutch size, testes size, sperm length, age at sexual maturity, longevity, body size and sexual size dimorphism） among different populations within species along geographical gradients for anurans in China in recent years. We also provide future directions for studying difference in sperm performance between longer and shorter sperm within a species through transplant experiments and the relationships between metabolic rate and brain size and life-history.

Reproductive Strategy and Cycle of the Toad-headed Agama Phrynocephalus grumgrzimailoi(Agamidae) in Xinjiang,China

The reproductive strategy and cycle of Phrynocephalus grumgrzimailoi were studied at a locality close to Urumqi City, Xinjiang, China. The hatchlings of P. grumgrzimailoi need at least two years to reach sexual maturity, with the smallest mature male and female measured 48.02 mm and 47.01 mm snout-vent length(SVL), respectively. Adult females produce a single clutch per breeding season, with the clutch size ranging from 1 to 5. The clutch size and mass are significantly correlated with female SVL. There is no correlation of mean egg size with clutch size and relative fecundity in P. grumgrzimailoi, suggesting that the trade-off is absent between mean egg size and number. Females increase reproductive output mainly through increasing egg numbers. The copulation period lasts from April to June. Females begin vitellogenesis in April and lay eggs from May to July. Our results suggest that toad-headed lizards tend to select different reproductive strategies to adapt themselves to their arid or semi-arid habitats.

Age,growth and reproduction of Sarcocheilichthys nigripinnis from the Qingyi Stream in the Huangshan Mountains

Identifying the life-history strategies of fish and their associations with the surrounding environment is the basic foundation in the conservation and sustainable utilization of fish species.We examined the age,growth,and reproduction of Sarcocheilichthys nigripinnis using 352 specimens collected monthly from May 2009 to April 2010 in the Qingyi Stream.We found the sex ratio of this study population was 0.58:1(female:male),significantly different from expected 1:1.Females and males both comprised four age groups.The annuli on the scales were formed during February and March.No obvious between-sex difference was observed in length-weight and length-scale-radius relationships.The total length in back-calculation significantly increased with age for both sexes,but did not differ significantly at each age between the two sexes.An inflection point was observed in the growth curves given by the von Bertalanffy growth function for total weight.At this inflection point,fish were 3.95 years.Both sexes reach their 50%sex maturity at age 2,when females and males were 94.7 mm and 103.0 mm total length.The temporal pattern of the gonado-somatic index corresponded to a spawning period that occurred from April through July.The non-synchronicity of egg diameter in each mature ovary during the breeding period suggested these fish may be batch spawners.The absolute fecundity increased significantly with total length and weight,whereas no significant correlation was observed between the relative fecundity and body size.

Field Surveys Suggest Biennial Reproduction Cycle and Competition-triggered Dispersal of the Endangered Chinese Crocodile Lizard

The endangered Chinese crocodile lizard(Shinisaurus crocodilurus)is a habitat specialist living in streams of mountain forests in southern China and northern Vietnam.Conservation efforts are increasing for recovering its wild populations.However,the growth,reproduction,and dispersal ability of crocodile lizards in the wild are largely unknown.We conducted field surveys of the crocodile lizard population in Daguishan National Nature Reserve,one of the largest extant wild populations of crocodile lizards,for three consecutive years in Guangxi,China.We found that crocodile lizards generally reach sexual maturity at the age of 2.5 years in the wild.Unlike most viviparous lizards,which reproduce annually,the crocodile lizard shows a biennial reproductive cycle.The number of observed juveniles and subadults fluctuated between years,whereas that of adults remained relatively stable.Non-adults had longer three-year dispersal distance than adults.Crocodile lizards showed preference for backwater pools in the stream.Competition for better resources may be the main trigger for dispersal.

Influences of fisheries management measures on biological characteristics of threadfin bream(Nemipterus virgatus)in the Beibu Gulf,South China Sea

Long-term variations in population structure,growth,mortality,length at median sexual maturity,and exploitation rate of threadfin bream(Nemipterus virgatus)are reported based on bottom trawl survey data collected during 1960-2012 in the Beibu Gulf,South China Sea.Laboratory-based analyses were conducted on 16791 individuals collected quarterly in eight different sampling years.Average body length,estimated asymptotic length,and percentage of large individuals have decreased significantly with the growth of marine catch and fishing power,indicating individual miniaturization of this fish species.Estimated exploitation rates indicate that the N.virgatus stock in the Beibu Gulf was moderately exploited in 1960 and 1962 and overexploited after 1992.This stock was taking a good turn in status in 2012,with the lowest exploitation rate since 1992 and ceased downward trend in length indexes.These results suggest that management measures to reduce fishing pressure may have a positive influence on the biological characteristics of this commercial fish species.Biological characteristics of most commercial fish species have phenotypic plasticity and might change over years in response to fisheries management.Therefore,attentions should be paid on variations in fish biological characteristics,when evaluating the effectiveness of current measures to control the total catch for all fisheries.

Identification and expression of epidermal growth factor gene in mouse testis

Epidermal growth factor (EGF) is produced primarily by Leydig cells of human testis. Expression of the EGF gene was assessed in mouse testis during the course of sexual maturation by the application of the RT-PCR method and the use of specific oligonucleotide primers. Testis EGF mRNA content increased with the developmental age of the mice, i.e., day 15 < day 30 < day 45 postnatal. The expression of the EGF gene appears to correlate with maturation of the testis and proliferation of Leydig cells.

Sex-Based Variation of Gene Expression in the Gonads and Fins of Russian Sturgeon (<i>Acipenser gueldenstaedtii</i>)

Russian sturgeon (Acipenser gueldenstaedtii) is a primitive freshwater fish and a source of black caviar. The genes involved in sexual determination and differentiation are still unknown and there are no molecular markers for sex identification in this species. Studying the variation of the sex-based differences in genomic sequences and in gene expression in the sturgeon may lead to markers of sex in early stages of development and advances in aquaculture, as well as provide novel insights about the evolution of reproduction, sex determination, and sexual differentiation mechanisms in vertebrates. Previous studies by our and other groups have identified differentially expressed genes in the gonads of adult female and male sturgeon. The current study aimed to test whether these genes were also differentially expressed in non-gonadal tissue, namely fins. We measured by qRT-PCR the mRNA levels of 29 known and novel sex-related genes in the gonads and fins of males (4 years old) and females (7 years old;sexual maturation is earlier in males than in females). Six genes (ATP6, IGFRM, LIA1A, S1A, NPL1A, GAPDH and SOX9) showed higher expression in female fins. However, only ATP6 mRNA levels differed in fins of males and females of the same age (4 years old). These findings underscore the impracticality of sex identification based on gene expression in non-gonadal tissue and the need for genetic sex markers in the Russian sturgeon.

Oligospermia due to partial maturation arrest responds to low dose estrogen-testosterone combination therapy resulting in live-birth: a case report

A man having severe oligospermia, due to partial maturation arrest at spermatid stage, was given low dose estrogen-testosterone combination therapy for three months. His sperm count increased enormously, following which his wife conceived and delivered a healthy baby at term.

On the identification of paedomorphic and overwintering larval newts based on cloacal shape： review and guidelines

Paedomorphosis is an alternative process to metamorphosis in which adults retain larval traits at the adult stage. It is frequent in newts and salamanders, where larvae reach sexual maturity with- out losing their gills. However, in some populations, larvae overwinter in water, while remaining immature. These alternative ontogenetic processes are of particular interest in various research fields, but have different causes and consequences, as only paedomorphosis allows metamor- phosis to be bypassed before maturity. It is thus relevant to efficiently identify paedomorphs ver- sus overwintering larvae. In this context, the aim of this article was 3-fold： firstly, to perform a meta-analysis of the identification procedures carried out in the literature; secondly, to determine the effectiveness of body size to make inferences about adulthood by surveying natural newt popu- lations of Lissotriton helveticus and Ichthyosaura alpestris, and thirdly, to propose easy guidelines for an accurate distinction between large larvae and paedomorphs based on an external sexual trait, which is essential for reproduction--the cloaca. More than half of the studies in the literature do not mention the diagnostic criteria used for determining adulthood. The criteria mentioned were the presence of mature gonads （10%）, eggs laid （4%）, courtship behavior （10%）, and external morphological sexual traits （39%） including the cloaca （24%）. Body-size thresholds should not be used as a proxy for paedomorphosis, because overwintering larvae can reach a larger size than paedomorphs within the same populations. In contrast, diagnosis based on cloacal external morphology is recommended, as it can be processed by the rapid visual assessment of all caught specimens, thus providing straightforward data at the individual level for both sexes.