Relationship between vitamin C and plasma concentrations of testosterone in female rainbow trout,Oncorhynchus mykiss

Two-year old rainbow trout females were fed diets containing 0, 30, 110, 220, 440 and 870 mg kg^-1 ascorbyl-2-monophosphate Mg⁺ salt (groups 1, 2, 3, 4, 5, and 6, respectively) from August until March. At the time of spawning (February–March) blood was sampled and the ovulating females were hand stripped. Estradiol (E₂) and testosterone (T) concentrations in plasma, and ascorbic acid (AA) concentrations in plasma and eggs were determined. The mean plasma concentrations of T were higher in group 4, 5, or 6 than in group 2 or 3 (p < 0.05). Moreover, the average plasma concentration of T in fish fed the diets with AA level below National Research Council (NRC) recommendations (groups 1, 2 and 3) was significantly lower (p<0.01) than the average plasma concentration in fish fed diets with AA level above NRC recommendations (groups 4, 5, and 6). These data are consistent with the hypothesis that AA can influence production of steroids in female rainbow trout.Corresponding author     

Effect of d-Lys6 salmon sGnRH alone and in combination with domperidone on the spawning of common carp during the late spawning season

The effect of [d-Lys6] salmon gonadotropin-releasing hormone alone (sGnRH) and in combination with domperidone, a dopamine antagonist, on the spawning of common carp, Cyprinus carpio, was investigated during the late spawning season (when mature fish stop spawning under natural conditions when males and females are put together). Fish were induced to spawn by [d-Lys6]-sGnRH salmon gonadotropin-releasing hormone analogue (sGnRH-X) only when injected in combination with domperidone at doses of 10 g kg-1 and 20 mg kg-1 body weight respectively. [d-Lys6]-sGnRH-X alone did not induce spawning at a dose as high as 100 g kg-1 body weight. Fish injected with domperidone alone did not spawn either. These results demonstrate that [d-Lys6]-sGnRH-X in combination with a dopamine antagonist is effective in inducing spawning during the late spawning season.     

光滑河蓝蛤生殖习性初步研究

光滑河蓝蛤一年有2次产卵高峰期,分别为在5月初和9月底。在产卵高峰期,通过人工授精方法,可获得受精卵并正常发育。在秋季性腺切片中发现1例雌性滤泡周围有呈集中式分散状态分布的精子,经分析初步认定是雌雄同体现象。     

The importance of individual behaviour for successful settlement of juvenile plaice (Pleuronectes platessa L.): a modelling and field study in the eastern Irish Sea

To study the transport of plaice (Pleuronectes platessa L.) eggs and larvae in the eastern Irish Sea, we constructed a 3D‐baroclinic physical model and coupled it to a particle‐tracking scheme that allowed aspects of larval behaviour to be simulated. Starting positions for eggs were based upon data from a series of ichthyoplankton surveys and final positions were compared with results of settled plaice distributions from two beam trawl surveys conducted on beaches around the eastern Irish Sea. If simulated larval behaviour was limited to passive drift or horizontal swimming, the particles diffused away from the spawning areas but failed to reach nursery grounds in significant numbers (85–90% remaining offshore). In contrast, switching on circatidal vertical swimming significantly increased the numbers of larvae reaching the coast (only 23–30% remained offshore). Particles tended to accumulate in bays and estuaries and this pattern compared well with the distribution of settled plaice from the field surveys. Studies in the southern North Sea (where spawning and nursery grounds are widely separated) have also demonstrated the importance of selective tidal stream transport for successful recruitment of settling plaice to nursery grounds. Although our understanding of the ontogeny of this behaviour is still poor, the model results presented suggest that this aspect of behaviour is a key factor influencing plaice settlement success.     

中世纪暖期的中国东部沙地

 中世纪暖期是冰后期的又一次温暖期,研究表明,当时世界许多地区均出现不同程度的气温回升现象,而且气温回升与20世纪初气候变暖现象类似。为探讨该期中国东部沙地的气候环境状况,利用已有的研究成果,对中国东部沙地若干古土壤和河湖相沉积进行分析。结果表明,中世纪暖期,东部沙地普遍发育古土壤或河湖相沉积,气候温暖湿润,流沙固定,沙地面积缩小,植被盖度增加,沙地形成干草原—疏林草原景观。弄清中世纪暖期东部沙地气候状况,可为其未来气候环境演变趋势研究提供基础参考。     

The spawning migration and conservation of smelt Osmerus eperlanus in the River Cree, southwest Scotland

The anadromous smelt Osmerus eperlanus population associated with the River Cree on the Solway Coast, southwest Scotland, is the only one remaining from several which previously occurred in that area. Their spawning migration was studied as a basis for conservation and management proposals. The timing and location of the onset of spawning in February/March was determined by regular inspection of the river bed for smelt eggs. The thermal regime in the lower river during preceding weeks is considered the primary factor in initiating spawning, but prevailing temperature, tide and flow conditions determine exactly where and when. Several local factors must be addressed for future conservation and management, e.g. commercial netting, pollution and the present physico-chemical character of the river. The reintroduction of smelt to other rivers on the Solway Coast should now be seriously considered.     

滩地淹水胁迫对杨树生长与木材显微结构的影响

对5种不同淹水时间类型滩地1～10年生杨树单株材积生长动态进行了分析．结果表明。不同类型之间单株材积生长量均存在显著差异．且随着林龄增长，其差异逐步减小；不同淹水胁迫下，当年年轮宽度、纤维细胞数量、木材基本密度均存在显著差异，纤维长度和宽度差异不显著，杨树年轮宽度与径向纤维细胞数、导管数、径向纤维比量呈正相关；随淹水胁迫程度加深，当年形成层细胞分裂受到了显著抑制，纤维细胞以及导管数量减少，林木径向生长量下降．径向导管比量提高，纤维比量下降，细胞壁腔比减小，木材密度明显降低．对5种淹水类型滩地的林木生长进行了系统聚类，合并划分为4种生长类型，对其中3种常规造林宜林类型杨树生长潜力进行了预测。     

长江刀鲚生殖洄游过程中血清能量指标变动

为探究刀鲚(Coilia nasus)生殖洄游过程中血清能量指标的变动情况,于2019年4月15日 ~ 6月5日,在长江崇明段、镇江段和安庆段使用刺网采集刀鲚,对49尾刀鲚血清样本的能量指标进行测定分析。结果显示,自崇明至安庆的洄游过程中血糖、总胆固醇、低密度脂蛋白含量均无显著差异(P>0.05),血清总蛋白、甘油三酯、高密度脂蛋白和游离脂肪酸含量在镇江至安庆段均无显著差异(P>0.05),出现显著差异的过程主要集中在崇明至镇江段,总蛋白和甘油三酯含量显著降低(P<0.05),分别下降19.36%和29.29%;高密度脂蛋白和游离脂肪酸含量显著升高(P<0.05),分别上升60.38%和23.65%;安庆段卵巢发育至不同时期的刀鲚样本中,Ⅳ期样本的甘油三酯含量于Ⅱ期和Ⅲ期样本均存在显著差异(P<0.05),分别上升67.24%和53.75%,其余指标在各发育期样本间均无显著性差异(P>0.05)。综上所述,自崇明至镇江段,刀鲚血清样本甘油三酯、高密度脂蛋白和游离脂肪酸等血脂相关指标出现显著性变化(P<0.05),表明刀鲚在洄游前期脂质代谢活跃,脂肪应是其洄游及发育的主要供能物质;自镇江至安庆段,其代谢水平对洄游及性腺发育的能量需求逐渐适应,因此洄游后期刀鲚血清能量指标总体趋于平稳。     

齐口裂腹鱼卵巢发育的组织学研究

采用石蜡组织切片和扫描电镜法,对齐口裂腹鱼卵巢发育进行了组织学研究。结果表明:卵母细胞的发育分为5个时相,卵巢发育可分为6个时期。第2时相卵母细胞中具有卵黄核、围核透明层,并可见核仁物质外排现象;液泡中的内含物和卵黄颗粒呈现多种形态;卵母细胞发育过程中,核仁数增加较多;卵膜由质膜和放射带组成。在第5时相成熟卵子的受精孔中仍有精孔细胞堵塞。产卵时间为2月下旬至4月下旬,属分批同步产卵类型。     

光泽黄颡鱼繁殖的初步研究

对嘉陵江中的光泽黄颡鱼的繁殖作了初步研究。其中主要研究了光泽黄颡鱼的生殖群体、繁殖力和胚胎发育。采用LRH-A加鲢鱼脑垂体催产光泽黄颡鱼获得成功,催产适宜水温22-25℃,效应时间10-18h,胚胎发育较快,感官、上颌须、心脏跳动等在出膜之前出现。