Genotyping,pedigree reconstruction and endocrinological characterization of Acipenser naccarii (Bonaparte, 1836) using microsatellite markers and plasma steroid levels

This study aimed to set up a method for the long‐term management of Adriatic sturgeon, through the analysis of sex steroids and the genetic profiling of individuals in order to maximize the already reduced genetic variability of this species. Ten A. naccarii adults (nine of captive origin, one captured in the Ticino river and then moved into captivity) and eight subadults located in a semi‐natural land‐locked pond in Abbiategrasso (Milan, Italy) were analysed. Plasma testosterone differed significantly in the eight analysed subadults allowing their differentiation into two groups: the first group with an average testosterone concentration of 5.42 ± 1.31 ng/ml (probably female) and the second group with an average of 423.14 ± 75.97 ng/ml (probably male), as subsequently confirmed by artificial stripping. The plasma testosterone level was also significantly different between adult males and females (371.37 ± 43.58 vs. 95.34 ± 51.10 ng/ml), while the E2 levels showed no significant differences. Animals were genotyped on the basis of 10 microsatellite loci and their parental relationships were defined: four adults, two females and two males, generated the eight subadults. On the basis of pedigree analyses and genetic distances, 15 unrelated couples were identified for the future breeding seasons. Finally, the adult female captured in the Ticino River showed an interesting genetic profile, widely different from all of the other 17 specimens analysed, and represents a valuable source of genetic diversity.     

脉红螺交配后性选择机制

交配后性选择是雌性混交动物中的一种普遍现象,其选择机制较为复杂,是性选择研究领域中的重点和难点问题.脉红螺是我国重要的大型经济贝类之一,繁殖形式为多雌多雄混交模式.为了研究该模式繁殖机制,本研究利用6个微卫星标记及行为学观察对脉红螺3个家系进行父权分析.结果表明,3个家系均存在多父性现象,证实脉红螺繁殖属于真正遗传意义上的雌性混交模式.3个家系中父权比例与父本的6个形态学参数及交配持续时间不存在关联性,但均表现出最先与母本交配的父本其后代比例最高,而最后交配的父本其后代比例最低,表明脉红螺交配后性选择存在最先雄性精子优先受精现象,这一现象符合“topping off”假说,即最先交配的雄性排放了大量精子占据了受精囊的主要空间,导致其子代的比例最高;而最后交配的雄性由于受精囊空间的限制,其精子占据空间最少.本研究为海洋无脊椎动物的交配后性选择机制研究提供重要参考资料.     

金乌贼性腺发育的特征及初次性成熟胴长估算

作为我国重要的头足类资源,金乌贼（Sepia esculenta Hoyle, 1885）具有较高的经济价值和营养价值。为探究金乌贼性腺发育、胴长体质量关系、初次性成熟胴长（ML50）,本文根据2017-2022年拖网渔船在东海北部外海（123.0°E-127.5°E,27.5°N-31.5°N）采集的金乌贼调查数据,分别通过统计学分析探究胴长和体质量组成及性腺发育,采用基于性腺成熟度的逻辑斯蒂方程和多项式胴长体质量方程估算初次性成熟胴长。结果显示,金乌贼雌雄个体优势胴长组分别为80-120 mm、80-140 mm;优势体质量组分别为40-280 g、40-200 g。金乌贼为负异速生长（b<3）;不同阶段的雌性a、b值不同,雄性a、b值相近。调查期间（9月至翌年3月）,性腺随时间发育;160 mm以上的胴长组中未有Ⅰ期个体被发现。应用逻辑斯蒂方程和多项式胴长体质量模型估算ML50结果分别为：雌性124.30mm、127.98mm、雄性129.18mm、142.44mm。基于多项式胴长体质量方程估算的ML50拟合效果更好。研究表明,金乌贼存在明显的季节性生殖特征,繁殖期为1-3月;雌性在性成熟期间能量更多的从身体生长转变为性腺发育;建议东海外海金乌贼雌、雄个体最小开捕胴长应当分别大于127.98mm、142.44mm。     

性成熟和个体大小对智利外海茎柔鱼耳石生长的影响

根据2007-2008年智利外海茎柔鱼资源调查期间采集的样本,以耳石最大宽度MW与其总长TSL之比作为表征耳石生长的指标,利用方差分析研究性成熟和个体大小对耳石生长的影响。分析认为,雌性个体的耳石MW/TSL与性腺成熟度存在相关性,性成熟度Ⅰ级与Ⅲ级、Ⅱ级与Ⅲ级个体的耳石MW/TSL存在显著差异(P<0.05);而雄性个体的耳石MW/TSL与性腺成熟度无关。雌性个体的耳石MW/TSL与胴长也存在着相关性,胴长300～400mm的个体与500～600mm和600～700mm、胴长400～500mm与500～600mm和600-700mm的雌性个体,它们耳石MW/TSL差异显著(P<0.05),胴长为400～500mm至500～600mm的个体,其MW/TSL增加迅速,差异极显著(P<0.01)。胴长350～400mm与400～500mm、400～450mm与450～500mm的雄性个体,它们耳石MW/TSL也存在显著差异(P<0.05),胴长400～450mm时的MW/TSL值为最小。研究表明,性成熟和个体大小对智利外海茎柔鱼耳石的生长有影响,但雌雄个体有差别。     

Reproductive characteristics of the fishery important temperate demersal berycid Centroberyx gerrardi indicate greater reproductive output in regions of upwelling

The reproductive biology of Centroberyx gerrardi (Günther) was investigated across ~2,000 km of its southern Australian distribution, encompassing different jurisdictions and varying environmental features. Greater gonad mass and prevalence of spawning fish, along with lower ratios of lengths at maturity:maximum lengths and ages at maturity:maximum ages, were identified at the western‐most (Capes) and eastern‐most (Great Australian Bight; GAB) regions. Across the study region, spawning peaks in summer/autumn, when water temperatures are warmest. Regional differences in potential “reproductive output,” while not consistent with the eastward decline in mean monthly water temperature, may instead be related to summer upwelling in the Capes and GAB, driving greater oceanic productivity prior to peak spawning, supporting larval survival. In autumn, the prevailing southward and eastward flowing, downwelling Leeuwin Current (LC) strengthens, providing a dispersal mechanism along the west and south Australian coasts, but limiting upwelling effects. Predicted changes in environmental conditions and their potential impacts on C. gerrardi are discussed, in particular how these factors may affect recruitment to stocks and fisheries, requiring a better understanding of source‐sink relationships for this species. As environmental changes occur, management strategies to sustain fish resources must adapt to spatially variable and changing reproductive output and be collaborative across jurisdictions.     

The effect of timing of extended photoperiod on growth and maturity of brook trout (Salvelinus fontinalis)

The influence of timing of extended photoperiods on growth and maturity of brook trout was investigated in a 112‐day experiment. The fish with mean initial weight of ~192 g were reared under four light regimes: one control group with natural ambient photoperiod and three groups exposed to an 18L:6D regime initiated at days 1, 23 or 46 of the growth trial. Light‐emitting diodes, with intensity of 250–1000 lux, depending on the distance from the light source, were used for extending light periods. There was a positive effect of prolonged day length on fish growth (p < 0.05), and a delay in gonad development and sexual maturity. Significantly higher numbers of sexually mature fish were found among controls groups, regardless of sex. Survival rate was not affected by light regime. This study demonstrated that the short‐term expansion of the photo period delayed maturation and increased the growth rate of brook trout.     

Effects of Estradiol and Testosterone on the Expression of Growth‐related Genes in Female and Male Nile Tilapia,Oreochromis niloticus

Nile tilapia exhibits strong sexual growth dimorphism. The potential role of sex steroid hormones in sexual growth dimorphism is not fully understood. We investigated the effects of estradiol (E₂) and testosterone (T) on growth rate, plasma sex hormones, and expression of growth hormone (GH)‐insulin‐like growth factor (IGF) axis genes and muscle regulatory factor (MRF) genes in female and male Nile tilapia. The results revealed that serum concentrations of E₂ and T were significantly higher after correlative injection (P < 0.05). Compared to male fish, female fish had lower growth rates. E₂ increased growth performance in females with no significant effects on males, whereas T significantly increased growth performance in males, with no significant effects on females. In females, E₂ significantly increased expression of ghr1, ghr2, igf1, and igf2, while T decreased igf2 and increased ghr1 and ghr2 expression. In males, T increased expression of igf1, igf2, ghr1, and ghr2, and E₂ decreased expression of igf1, ghr1, and ghr2. Additionally, E₂ and T enhanced the expression of MRF genes (myod1, myod2, myog, and myf5) in female and male fish, respectively. The results suggest that sex steroid hormones play a role in sexual growth dimorphism by regulating the expression of GH‐IGF axis and MRF genes.     

食用菌有性发育相关基因的研究进展

从构巢曲霉veA基因的发现出发,以研究时间先后为顺序,总结了近30 a来发现的与食用菌有性发育相关的基因及其作用,其中重点介绍了双孢菇、香菇和冬虫夏草中有性发育相关基因的功能,并对今后食用菌有性发育的研究进行了展望。     

温度、湿度和光照对苹果炭疽叶枯病菌(Glomerella cingulata)产孢的影响

苹果炭疽叶枯病(Glomerella cingulata)是我国苹果上新发现的一种病害,为了了解病原菌的产孢条件和产孢动态,为病害的预测预报与防控提供依据。本研究在人工控制条件下,测试了温度、湿度和光照对苹果炭疽叶枯病菌产生分生孢子和子囊孢子的影响。结果表明,苹果炭疽叶枯病新形成的病叶润湿后,在15℃~30℃下保湿培养2~6 d后可产生大量橘黄色的分生孢子堆,其中30℃下产孢量最大,产孢速度最快,仅需2 d时间。炭疽叶枯病菌在新形成的病叶上于15℃~30℃下培养20~30 d可形成子囊孢子,最适温度为25℃,子囊孢子的形成需要高湿环境或叶片润湿。炭疽叶枯病菌的单孢分离菌株于15℃~25℃下,在马铃薯葡萄糖琼脂培养基(PDA)上培养20~30 d也可形成子囊孢子,最适产孢温度25℃。紫外光、黑光和日光都能促进子囊孢子的形成。     

藤仓赤霉菌色素形成能力的遗传研究

通过菌株的无件继代培养和有性杂交方法,对藤仓赤霉菌(串珠镰孢霉)形成色素的能力及其遗传稳定性进行研究.试验结果表明,串珠镰孢霉产生色素的能力在无性后代中稳定遗传;从色素形成量不同的菌株间杂交试验结果,首次提出由单主效基因控制色素前体产生,而表型色素产生量的多少受一定数量微效基因控制,且这些微效基凶与色素产生量以及色素形成的快慢有关.