The demonstration of chemosensory food detection in Hymenocera picta Dana (Decapoda, Caridea), a proposed predator of the crown-of-thorns starfish Acanthaster planci (L)

Hymenocera picta, the painted shrimp, is a possible predator of A canthaster planci. the crown-of-thorns starfish. H. picta detects food by chemical cues alone and visual cues play no part in the initial location of prey. The presence of food in the water causes the shrimp to become more active, and distance chemoreceptors are probably present in the antennules of the shrimp. Extract of A. planci has statistically similar attractive powers to an extract of Linckia multifora, the starfish supplied as food to the shrimps. The painted shrimp was not attracted to fish extract (Chaetodon sp.) and may respond only to starfish. It is suggested that although H. picta is able to kill and feed on small juvenile A. planci. it is probably an ineffective predator against larger adult Crown-of-thorns starfish.

A key to the families and genera of freshwater fishes of Tanzania

The purpose of this key is to facilitate rapid and accurate identification, in the field, for fisheries workers. It is therefore based as much as possible on external characters only and an attempt has been made to keep it simple and straight forward. The only real difficulty arises in clearly demarcating the numerous cichlid genera of the great lakes, despite the fact that these have been treated in separate sections for each lake. Moreover, it hasn't been possible to revise the key to the lake Nyasa genera (taken from Jackson, 1961) to any significant extent, my experience with L. Nyasa fishes being limited; also, a few new genera have been or are still in the process of being published and I unfortunately haven't had access to these papers. A short bibliography is appended covering the major publications relevant to the systematics of Tanzania freshwater fishes and the sources from which these keys have been drawn up.

树鼩CXCR4cDNA的克隆和序列分析

　目的　获得树　CXCR4 的cDNA 序列,探讨其是否可以支持HIV-1 病毒和细胞的结合。方法　设计 相应的引物, 用RT- PCR ,基因克隆,DNA 序列分析技术。结果　获得了全长为1059bp 树　CXCR4 (tsCXCR4) 基因 的cDNA。发现其核苷酸序列与人的CXCR4 (hCXCR4) 基因的cDNA 有9218 % 的相似性,由此推导出的氨基酸序列 有9619 % 相似性。与hCXCR4 功能相关的关键位点完全相同,tsCXCR4 的N 端第7 和12 位点为酪氨酸,第14、15 和 32 位点为谷氨酸,胞外环第183 ,188 为精氨酸, 第193、262 位点以及跨膜区97 位点为天冬氨酸。结论　树　的CX2 CR4 很可能会作为HIV-1 的辅助受体。　

Lyapunov's stability and operational margin of grid-connected photovoltaic modules

Analyses of photovoltaic power generation based on Lyapunov's theorems are presented. The characteristics of the photovoltaic module and the power conditioning unit are analyzed in order to establish energy functions that assess the stability of solutions and define safe regions of operation. Furthermore, it is shown that grid-connected photovoltaic modules driven at maximum power may become unstable under normal grid transients. In such cases, stability can be maintained by allowing an operational margin defined as the energy difference between the stable and the unstable solutions of the system. Simulations show that modules cope well with grid transients when a sufficiently large margin is used.

Dose-dependent effects of the dopamine D1 receptor agonists A77636 or SKF81297 on spatial working memory in aged monkeys

With advancing age, monkeys develop deficits in spatial working memory resembling those induced by lesions of the prefrontal cortex (PFC). Aged monkeys also exhibit marked loss of dopamine from the PFC, a transmitter known to be important for proper PFC cognitive function. Previous results suggest that D1 agonist treatment can improve spatial working memory abilities in aged monkeys. However, this research was limited by the use of drugs with either partial agonist actions or significant D2 receptor actions. In our study, the selective dopamine D1 receptor full agonists A77636 and SKF81297 were examined in aged monkeys for effects on the working memory functions of the PFC. Both compounds produced a significant, dose-related effect on delayed response performance without evidence of side effects: low doses improved performance although higher doses impaired or had no effect on performance. Both the improvement and impairment in performance were reversed by pretreatment with the D1 receptor antagonist, SCH23390. These findings are consistent with previous results demonstrating that there is a narrow range of D1 receptor stimulation for optimal PFC cognitive function, and suggest that very low doses of D1 receptor agonists may have cognitive-enhancing actions in the elderly.