N-糖蛋白去糖基化酶（PNGase）的研究进展

N-糖蛋白去糖基化酶（PNGase）是一种广泛存在于真菌、植物、哺乳动物中的去糖基化酶，可以水解N-糖蛋白或 N-糖肽上天冬酰胺与寡糖链连接的化学键，并释放出完整的N-寡糖。PNGase在生物体内参与蛋白质降解、器官发育、个体生长等过程。人PNGase基因功能缺陷会导致先天性去糖基化障碍，小鼠PNGase缺陷会导致胚胎致死性，线虫PNGase缺陷使其寿命下降。本文对PNGase在不同物种的分布、蛋白质结构、酶学功能及生物学功能进行阐述，为PNGase的生理病理功能及致病机制的基础研究提供思路，为PNGase作为糖生物学工具酶或药物开发的创新应用研究奠定基础。     

Comparison of the roles of neurohormones in the regulation of blood distribution from the hearts of American and Japanese lobsters

The decapod cardiovascular system consists of a single ventricle that pumps blood into seven arteries; previous work has shown that the outflow distribution patterns of intact animals are variable. In the present study, flow recordings were made from pairs of arteries in semi-isolated hearts whilst different cardioactive hormones were infused into the heart. Each hormone (5-hydroxytryptamine, octopamine, dopamine, proctolin and F1) changed the outflow pattern, heart rate and ventricular pressure in a unique way. The probable sites of hormone action are the cardioarterial valves located at the origin of each artery except one, the dorsal abdominal. Outflow from the dorsal abdominal is controlled downstream by valves located at the origin of the segmental lateral arteries. The responses to a particular hormone were sometimes different between the hearts of American and Japanese lobsters. Accepted: 11 May 1998     

Parameter estimation for the distribution of single cell lag times

In Quantitative Microbial Risk Assessment, it is vital to understand how lag times of individual cells are distributed over a bacterial population. Such identified distributions can be used to predict the time by which, in a growth-supporting environment, a few pathogenic cells can multiply to a poisoning concentration level.We model the lag time of a single cell, inoculated into a new environment, by the delay of the growth function characterizing the generated subpopulation. We introduce an easy-to-implement procedure, based on the method of moments, to estimate the parameters of the distribution of single cell lag times. The advantage of the method is especially apparent for cases where the initial number of cells is small and random, and the culture is detectable only in the exponential growth phase.     

A preliminary analysis of distribution patterns in a large, pantropical genus, Barleria L. (Acanthaceae)

Barleria L. (Acanthaceae) is a large, polymorphic, widespread genus of herbs and shrubs comprising about 300 species, occurring mainly in Africa and Asia but with one species, Barleria oenotheroides Dum.Cours., extending to the New World tropics. Recent completion of a monographic infra-generic classification of the genus (in which seven sections are recognised, and the names of four of these validated in this paper—see Appendix 1), has facilitated a comprehensive analysis of distribution patterns on a global scale. The richest representation of Barleria is in Africa where there are two centres of diversity, one in tropical East Africa (about eighty species) and the other in southern Africa (about seventy species). The number of species tails off rapidly to both the Far East and the West. Barleria shows a marked trans-Atlantic disjunction between West Africa and the Neotropics, with B. oenotheroides shared by these two regions. This type of disjunction, which is known in other genera of the family, cannot be adequately explained in Barleria on the basis of long-distance dispersal or past continental movements. There is a high degree of regional endemism (e.g. 75% for the Indian subcontinent) at both the species and sectional levels within this genus. The degree of similarity between regions is correspondingly low. The endemics in each region tend to belong to only one or a few of the sections. There are few truly widespread taxa within the genus. East and West Africa are the only regions in which all sections are represented. Sections Barleria and Prionitis C.B. Cl. are the most widespread in the genus; Sections Somalia (Oliv.) Lindau, Fissimura M. Balkwill and Stellatohirtae M. Balkwill are mainly restricted to Africa and Sections Chrysothrix M. Balkwill and Cavirostrata M. Balkwill are the most restricted, occurring mainly in India and Sri Lanka. On a local scale, many of the species show highly restricted, clumped distributions; this is apparently related to particular soil types and possibly to the short-distance, ballistic mode of seed dispersal. This account of the biogeography of Barleria is to be regarded as preliminary, as much taxonomic work at the species level remains to be done before a full-scale cladistic biogeographic account can be undertaken. Particular areas worthy of future investigation include establishing the centre of origin of the genus and investigating the basis for the high degree of endemism shown by many of the species.     

Mitogen-Activated Protein Kinase Kinase 3 Is Required for Regulation during Dark-Light Transition

Plant growth and development are coordinately orchestrated by environmental cues and phytohormones. Light acts as a key environmental factor for fundamental plant growth and physiology through photosensory phytochromes and underlying molecular mechanisms. Although phytochromes are known to possess serine/threonine protein kinase activities, whether they trigger a signal transduction pathway via an intracellular protein kinase network remains unknown. In analyses of mitogen-activated protein kinase kinase (MAPKK, also called MKK) mutants, the mkk3 mutant has shown both a hypersensitive response in plant hormone gibberellin (GA) and a less sensitive response in red light signaling. Surprisingly, light-induced MAPK activation in wild-type (WT) seedlings and constitutive MAPK phosphorylation in dark-grown mkk3 mutant seedlings have also been found, respectively. Therefore, this study suggests that MKK3 acts in negative regulation in darkness and in light-induced MAPK activation during dark-light transition.     

Sharp intense line in the bioluminescence emission of the firefly

Numerous investigations have been carried out on the spectral distribution of the light of different species of fireflies. Here we record the emission spectrum of the Indian species of the firefly Luciola praeusta Kiesenwetter 1874 (Coleoptera : Lampyridae : Luciolinae) on a color film. Green and red color-sectors, with an intense yellow one in between, appear in this spectrum. Intensity profile of this spectrum reveals a hitherto undetected strong narrow yellow line, which lies within the full-width-at-half maximum (FWHM) of the intensity profile. The spectrum recorded in a high-resolution spectrometer confirms the presence of this sharp intense line. This finding lends support to an earlier drawn analogy between the in vivo emission of the firefly and laser light.