Adjustment to climate change is constrained by arrival date in a long-distance migrant bird

Spring temperatures in temperate regions have increased over the past 20 years, and many organisms have responded to this increase by advancing the date of their growth and reproduction. Here we show that adaptation to climate change in a long-distance migrant is constrained by the timing of its migratory journey. For long-distance migrants climate change may advance the phenology of their breeding areas, but the timing of some species' spring migration relies on endogenous rhythms that are not affected by climate change. Thus, the spring migration of these species will not advance even though they need to arrive earlier on their breeding grounds to breed at the appropriate time. We show that the migratory pied flycatcher Ficedula hypoleuca has advanced its laying date over the past 20 years. This temporal shift has been insufficient, however, as indicated by increased selection for earlier breeding over the same period. The shift is hampered by its spring arrival date, which has not advanced. Some of the numerous long-distance migrants will suffer from climate change, because either their migration strategy is unaffected by climate change, or the climate in breeding and wintering areas are changing at different speeds, preventing adequate adaptation.     

Amino acid composition and sequence of kassinin,a tachykinin dodecapeptide from the skin of the African frog Kassina senegalensis

Summary Methanol extracts of the skin of the African amphibian Kassina senegalensis contain a dodecapeptide, kassinin, belonging to the family of tachykinins or physalaemin-like peptides. Kassinin, like all other natural tachykinins, possesses the characteristic C-terminal tripeptide Gly-Leu-Met-NH₂ and a phenylalanine residue in position 5 from the C-terminus. However, the amino acid sequence in the N-moiety of the molecule differs sharply from that of the other tachykinins.Supported in part by grants from the Consiglio Nazionale delle Ricerche, Roma.     

Acoustic localization in an ostariophysian fish

Summary Under approximate free field conditions acoustic localization could be demonstrated in an ostariophysian fish, the ide (Leuciscus idus). The efficient vibration links of both sacculi with the unpaired swimbladder (via the Weberian ossicles) do apparently not preclude directional hearing in this important group of freshwater fish.The authors gratefully acknowledge the efforts of Mr M. Kleisma in the conduction of preliminary laboratory and field experiments. We thank Dr J. Ringelberg for making available to us the field facilities of the Limnological Laboratory, University of Amsterdam. Dr E. Meelis, Institute of Theoretical Biology, Leyden, has checked the applied statistics.     

利用GBSSI和SBD作为“锚”将荧光素酶定位到淀粉粒中效果的比较

利用马铃薯淀粉粒结合型淀粉合成酶 I （GBSSI） 作为“锚”，在马铃薯淀粉粒形成时将荧光素酶 （LUC）定位到淀粉粒中. 并对GBSSI/LUC重组蛋白质在转基因淀粉粒中的定位与积累、重组蛋白质中GBSSI与淀粉粒的亲和性以及荧光素酶的活性等进行了分析. 结果表明，GBSSI/LUC重组蛋白质在马铃薯淀粉粒中获得了特异性表达，但与以微生物的淀粉粒结合结构域 （SBD） 作为“锚”的SBD/LUC重组蛋白质相比较， 它与淀粉粒的亲和性以及荧光素酶的活性均下降. 由此认为，在淀粉粒形成过程中，利用SBD作为 “锚”将荧光素酶蛋白质定位到淀粉粒中的效果要优于GBSSI.     

局部固支功能梯度板的横向弯曲研究

研究了局部固支功能梯度方板在横向均布载荷作用下的静力学问题。假设功能梯度材料由陶瓷和钢组成，材料弹性模量设计为沿着板的厚度方向按照幂指数形式连续变化，功能梯度方板的四个边均为局部固支，应用Kirchhoff薄板理论和虚功原理推导了板的静力学有限元方程。另分别考虑了各边50%固支和25%固支两种情况，在板材料为纯陶瓷和纯钢时，将所得结果与ANSYS软件结果对比，验证了所建模型的准确性。最后，重点分析了梯度指数对板面和边界最大挠度的影响。结果表明梯度指数和固支范围是决定最大挠度的关键参数，其中固支范围对边界上最大挠度的影响更大。