A pathway of the autotrophic CO2 fixation in Chloroflexus aurantiacus

Autotrophically grown cells of Chloroflexus aurantiacus B-3 were shown to possess activity of ATP-dependent malate lyase (acetylating CoA). ATP: malate lyase is supposed to be the specific enzyme of the cycle of the autotrophic CO₂ fixation, in which pyruvate synthase, pyruvate phosphate dikinase, phosphoenolpyruvate (PEP) carboxylase and malate dehydrogenase are involved as well. The main product of the CO₂ fixation cycle is glyoxylate, which could further be converted into 3-phosphoglyceric acid (3-PGA) in the reactions of either glycerate or serine pathway. The enzymes of both pathways were detected in C. auratiacus B-3. The results of the in vivo studies of glyxoylate and glycine metabolism, as well as the inhibitor analysis using fluoroacetate (FAc), isonicotinic acid hydrazide (INH), and 4-aminopterin (4-AP) confirm the operation of the proposed pathway in Chloroflexus.Abbreviations 3-PGA 3-phosphoglyceric acid - 4-AP 4-aminopterin - FAc fluoroacetate - INH isonicotinic acid hydrazide - MV methyl viologen - PEP phosphoenolpyruvate - THF tetrahydrofolate - TPP thiamine pyrophosphate     

On the Development of the Periblastic Sinus during the Embryogenesis of the Masked Greenling Hexagrammos octogrammus and Whitespotted Greenling H. stelleri (Scorpaeniformes: Hexagrammidae)

Russian Journal of Developmental Biology - Embryonic development observations of the masked greenling H. octogrammus and the whitespotted greenling H. stelleri inhabiting the Tauiskaya Bay of the...     

Evidence of covalent modification of glutamine synthetase in the purple sulfur bacterium Thiocapsa roseopersicina

Abstract It was shown that glutamine synthetase of purple sulfur bacterium Thiocapsa roseopersicina is regulated by covalent modification. This conclusion is made on the basis of results showing that: (i) incubation of cells under conditions of nitrogen deprivation in the light lead to an increase of glutamine synthetase activity; (ii) addition of ammonium to nitrogen-starved cell suspensions caused a rapid decrease of glutamine synthetase activity; (iii) inhibition of glutamine synthetase by feedback modifiers was higher in ammonium-treated cells than in those starved for a nitrogen source; (iv) treatment of purified glutamine synthetase and cell-free extracts with phosphodiesterase was accompanied by an increase of glutamine synthetase activity, indicating the cleavage of modifying residues covalently bound to glutamine synthetase molecules.     

A tale of two ferredoxins: sequence similarity and structural differences

Background  

Sequence similarity between proteins is usually considered a reliable indicator of homology. Pyruvate-ferredoxin oxidoreductase and quinol-fumarate reductase contain ferredoxin domains that bind [Fe-S] clusters and are involved in electron transport. Profile-based methods for sequence comparison, such as PSI-BLAST and HMMer, suggest statistically significant similarity between these domains.     

先天免疫

传统上将免疫系统分为先天性和适应性成分 ,它们各自具有不同的功能和作用。适应性成分围绕两类特异细胞即Ｔ 细胞和Ｂ 细胞组成。由于每个淋巴细胞呈现单一类型的结构独特的受体 ,在整个淋巴细胞群的抗原受体库是非常庞大并极富多样性的。这种庞大而多样的受体库增加了单个淋巴细胞通过其受体与抗原结合 ,从而启动细胞活化和增殖的可能性。这一过程叫做克隆选择 ,可用来解释适应性免疫系统的众多基本性质。感染时淋巴细胞的克隆放大对于产生有效免疫反应是绝对必要的 ,但产生足够的克隆数并分化成效应细胞往往要花 3～ 5天的时间 ,这期间大…