Lipid classes and fatty acids during embryogenesis of captive and wild silverside (<Emphasis Type="Italic">Chirostoma estor estor</Emphasis>) from Pátzcuaro Lake

Lipid classes and fatty acid levels were analyzed in freshly fertilized eggs, early and late embryo development, and freshly hatched larvae obtained from wild and captive silverside Chirostoma estor estor broodstock, as well as in plankton, Artemia, and pelleted feed. The concentration of triglycerides (TGs) and highly unsaturated fatty acids (HUFAs) in neutral lipid fraction significantly decreased during early development and especially after hatching, whereas phospholipids and HUFA in polar lipid fraction remained constant. These results indicate that TGs rather than PLs are used as energy sources and that all HUFAs [20:4n-6/arachidonic acid (ARA), 20:5n-3/eicosapentaenoic acid (EPA), and 22:6n-3/docosahexaenoic acid (DHA)] of polar lipids are selectively conserved during early development. High levels of DHA (30%, on average, of total fatty acids) and low levels of EPA (4%) were observed in eggs, embryos, and larvae and did not reflect the proportions of these fatty acids in food. Preferential accumulation of DHA from food consumed by broodstock, and then transference to eggs, was probably occurring. The main difference between eggs from both origins was a low level of ARA in eggs from captive fish (4% of total fatty acids) compared to wild fish (9%). This could be associated with a deficiency in the diet that is not compensated for by desaturation/elongation of 18:2n-6 and, possibly, with greater stress in captive fish. In any case, particular requirements of ARA should be determined to optimize the culture of C. estor.     

Ontogenetic development of digestive enzymes in yellowtail kingfish Seriola lalandi larvae

The development of digestive enzymes was examined in laboratory-reared yellowtail kingfish larvae from hatching to 36 days after hatching (DAH). The specific activities of amylase, lipase, and alkaline phosphatase showed three distinct phases: a sharp increase in enzyme activity from hatching to the onset of exogenous feeding on 3 DAH, followed by a fluctuation and a general decline toward 18 DAH, and then a period of low activity from 18 to 36 DAH. The total activities of these three enzymes showed a gradual increase from hatching to 18 DAH, followed by a sharp increase toward 36 DAH. In contrast to other enzymes, the specific and total activities of trypsin reached the maximum on 15 DAH and 24 DAH, respectively, and then both activities declined to low levels toward 36 DAH. The dynamics of digestive enzymes corresponded to the anatomical development of the digestive system. The enzyme activities tend to be stable after the formation of gastric glands in the stomach on 15 DAH. The composition of digestive enzymes indicates that yellowtail kingfish is able to digest protein, lipid and carbohydrates at an early stage. However, due to the low level of amylase specific activity after 18 DAH, the carbohydrate component should remain at a low level in formulated diets for fish larvae.     

星孢寄生菇的分离鉴定筛选及其生理特性相关性

开展星孢寄生菇（Asterophora lycoperdoides）的分离鉴定及其营养生理与个体发育相关性研究，以期为加快其他珍稀菇类的驯化进程奠定基础。从3株野生寄生菇属子实体中分离获得纯培养菌丝体，采用形态学与分子生物学鉴定其分类地位。以子实体湿质量与生物学效率为主要指标，筛选最优菌株及其基础培养基，并测定营养物的种类、增加倍数及其加入方式对最优菌株个体发育的影响。结果表明：两种鉴定方法结果一致，3株真菌均为星孢寄生菇。菌株YAASM4665在9种筛选培养基上的农艺性状优于其他菌株，最优基础培养基为小麦粉15 g、米饭35 g、水50 mL，pH自然。当基础培养基中的水增加至80 mL或用50 mL土豆汁代替，加入0.50%的葡萄糖，用等质量的黑豆粉代替小麦粉，营养物增加1/2倍以及营养物混合加入等单因素处理下，该菌株的农艺性状综合表现较好，其中土豆汁培养基子实体湿质量最大（4.86 g），黑豆粉培养基生物学效率最高（8.50%），基质中加入2%的葡萄糖时最有利于延迟厚垣孢子的形成。厚垣孢子形成期与其他农艺性状存在一定程度的相关性，菌丝萌发期与子实体湿质量是其主要影响因素。总之，星孢寄生菇个体发育受菌株遗传特性和营养因素的影响，厚垣孢子的形成不利于该菇子实体正常发育，菌丝萌发期对其综合影响最大，可为其他菇类的驯化提供参考。     

Responses of forest trees to single and multiple environmental stresses from seedlings to mature plants: Past stress history,stress interactions,tolerance and acclimation

Forest trees are exposed to a myriad of single and combined stresses with varying strength and duration throughout their lifetime, and many of the simultaneous and successive stress factors strongly interact. While much progress has been achieved in understanding the effects of single stresses on tree performance, multiple interacting stress effects cannot be adequately assessed from combination of single factor analyses. In particular, global change brings about novel combinations of severity and timing of different stresses, the effects of which on tree performance are currently hard to predict. Furthermore, the combinations of stresses commonly sustained by trees change during tree ontogeny. In addition, tree photosynthesis and growth rates decline with increasing tree age and size, while support biomass in roots, stem and branches accumulates and the concentrations of non-structural carbohydrates increase, collectively resulting in an enhancement of non-structural carbon pools. In this review, tree physiological responses to key environmental stress factors and their combinations are analyzed from seedlings to mature trees. The key conclusions of this analysis are that combined stresses can influence survival of large trees even more than chronic exposure to a single predictable stress such as drought. In addition, tree tolerance to many environmental stresses increases throughout the ontogeny as the result of accumulation of non-structural carbon pools, implying major change in sensing, response and acclimation to single and multiple stresses in trees of different size and age.     

Development of digestive enzyme activity in larvae of spotted sand bass <Emphasis Type="Italic">Paralabrax maculatofasciatus</Emphasis>. 1. Biochemical analysis

Spotted sand bass Paralabrax maculatofasciatus is a potential aquaculture species in Northwest Mexico. In the last few years it has been possible to close its life cycle and to develop larviculture technology at on pilot scale using live food, however survival values are low (11%) and improvements in growth and survival requires the study of the morpho-physiological development during the initial ontogeny. In this research digestive activity of several enzymes were evaluated in larvae, from hatching to 30 days after hatching (dah), and in live prey (rotifers and Artemia), by use of biochemical and electrophoretic techniques. This paper, is the first of two parts, and covers only the biochemical analysis. All digestive enzyme activities were detected from mouth opening; however the, maximum activities varied among different digestive enzymes. For alkaline protease and trypsin the maximum activities were detected from 12 to 18 dah. Acid protease activity was observed from day 12 onwards. The other digestive enzymes appear between days 4 and 18 after hatching, with marked fluctuations. These activities indicate the beginning of the juvenile stage and the maturation of the digestive system, in agreement with changes that occur during morpho-physiological development and food changes from rotifers to Artemia. All enzymatic activities were detected in rotifers and Artemia, and their contribution to enhancement the digestion capacity of the larvae appears to be low, but cannot be minimised. We concluded that the enzymatic equipment of P. maculatofasciatus larvae is similar to that of other marine fish species, that it becomes complete between days 12 and 18 after hatching, and that it is totally efficient up to 25 dah.     

光帽鳞伞子实体个体发育

对光帽鳞伞(Pholiota nameko)子实体发育观察发现,原基菌幕在球状原基时(原基直径750μm左右)已经存在,原基顶端菌幕(菌盖菌幕)厚,明显;底部菌幕(菌柄菌幕)较薄。菌盖、子实层、菌褶和菌柄上部均由原基中间的组织分化形成。原基上部有2个菌丝发育速率不同的区域生成菌褶腔,菌褶腔上缘菌丝致密、规则排列形成子实层。下缘菌丝稀疏,逐渐发育成菌柄的外围菌丝。菌褶的形成是由子实层内的菌丝生长不均匀而引起的。子实层发生较早,在菌盖与菌柄还没有形成雏形时就已经开始了最初的分化。菌盖表面由菌盖菌幕的一层胶质化的菌丝组织形成。成熟子实体中,菌盖菌幕完全胶质化,成为光滑的菌盖,菌柄菌幕强烈胶质化甚至消失。     

Immunocytochemical localization of gonadotropins during the development of XX and XY Nile tilapia

Gonadal development and steroidogenesis in teleosts is regulated by two gonadotropic hormones; luteinizing hormone (LH) and follicle-stimulating hormone (FSH). Earlier studies in tilapia have shown that FSH-β and LH-β appear by 14 days after hatching (dah), results from the current study corroborate with these previous reports in tilapia. Here we demonstrate the appearance of LH in pituitary between 14 and 20 dah. In addition to this the present study primarily focuses on any possible differences in appearance of LH-β and FSH-β immunoreactivity between XX and XY population of Nile tilapia. LH immunoreactivity was found to be lower in pituitary of XX fish when compared to XY fish. The development of FSH-β immunoreactivity in pituitary of the Nile tilapia is also presented. Overall, it remains to be established what significance these findings on the appearance of gonadotropins hold for sex differentiation in tilapia. F. Sakai and I. Swapna contributed equally.     

Ontogenetic changes in water-use efficiency (δC) and leaf traits differ among tree species growing in a semiarid region of the Loess Plateau,China

On the Loess Plateau, China, several planted tree species such as Populus hopeinsis and Robinia pseudoacacia suffer occasional diebacks in the top shoots, reducing growth rates after maturation. However, this does not usually occur in other species, e.g., Ulmus pumila and Zizyphus jujuba. We compared stable carbon isotope ratios (δ¹³C) as indicators of leaf water-use efficiency (WUE), leaf mass per unit area (LMA), and leaf area- and mass-based nitrogen content (N_area and N_mass) by tree height (1, 5, and 10 m) in P. hopeinsis, R. pseudoacacia, U. pumila, and Z. jujuba. In P. hopeinsis and R. pseudoacacia, leaf δ¹³C and N_area were significantly lower in 10-m trees than in 1-m saplings, indicating that leaf WUE and photosynthetic rates of both species decreased with tree height. In contrast, δ¹³C in Z. jujuba varied little with tree height. The δ¹³C of 10-m-tall U. pumila trees was significantly higher than that of 1-m plants, demonstrating an increase in WUE with tree height. Decreasing WUE, leaf N_area, and N_mass with height increases in P. hopeinsis and R. pseudoacacia may be related to water and nutrient limitations for these species in semiarid regions. In contrast, stable or increasing δ¹³C with tree height in U. pumila and Z. jujuba may account (to some extent) for successful production of these species under identical environmental conditions. Diameter growth rate also decreased with maturity in P. hopeinsis and R. pseudoacacia, but increased or was stable for U. pumila and Z. jujuba. The differences in leaf WUE and LMA among species with tree maturity may be related to species’ growth patterns and susceptibility to drought stress, and are likely to be important new criteria for plantation species selection on the Loess Plateau.     

多胺在高等植物个体发育中的作用

多胺作为具有调控作用的生理活性物质,与高等植物生长发育关系密切。大多数研究表明,多胺在一定的浓度范围内对种子萌发、植物生长与分化有促进作用。在植物花芽分化过程中,多胺水平会发生显著的变化,单独或混合外施Spm、Spd与Put能够促进花芽形成,增加花芽的数目。多胺对植物雌雄蕊、果实的发育与坐果具有重要调节作用,雌花与雄花所包含的多胺在种类及数量上均有差异。而多胺延缓衰老的作用在植物中普遍存在。因此,多胺参与了高等植物个体发育的各个环节。     

中华鲟眼球的早期发育

Histological studies on eyeball of the Chinese sturgeon, Acipenser sinensis showed that crystalline lens was laminated and musculi ciliaris was developed to crystalline lens. Iris was developed and optic nerve happened at 3 dph （days-post-hatch）. At 25 dph, visual cells of retina were developed. While eyeball tissues were developed at 60 dph and optic tract was thickened. The eye is small and accommodation of the Dens is weak. Therefore, it is may conclude that sense organ of vision of young Chinese sturgeon played an unimportant role in feeding behavior.