Occurrence of 5-methoxypodophyllotoxin in plants,cell cultures and regenerated plants of Linum flavum

The 5-methoxypodophyllotoxin contents of plants, cell cultures and regenerated plants of Linum flavum are compared. It is demonstrated that cell cultures are able to produce amounts of 5-methoxypodophyllotoxin that are comparable to the concentration in fully differentiated plants. The production of 5-methoxy-podophyllotoxin depends on the hormonal balance of the growth medium. The use of 2,4-dichlorophenoxyacetic acid as the growth regulator is favourable for 5-methoxypodophyllotoxin production when compared to naphthylacetic acid. The 5-methoxypodophyllotoxin accumulation appears to be positively related to the internal cell volume.     

Functional RelBE-Family Toxin-Antitoxin Pairs Affect Biofilm Maturation and Intestine Colonization in Vibrio cholerae

Toxin–antitoxin (TA) systems are small genetic elements that typically encode a stable toxin and its labile antitoxin. These cognate pairs are abundant in prokaryotes and have been shown to regulate various cellular functions. Vibrio cholerae, a human pathogen that is the causative agent of cholera, harbors at least thirteen TA loci. While functional HigBA, ParDE have been shown to stabilize plasmids and Phd/Doc to mediate cell death in V. cholerae, the function of seven RelBE-family TA systems is not understood. In this study we investigated the function of the RelBE TA systems in V. cholerae physiology and found that six of the seven relBE loci encoded functional toxins in E. coli. Deletion analyses of each relBE locus indicate that RelBE systems are involved in biofilm formation and reactive oxygen species (ROS) resistance. Interestingly, all seven relBE loci are induced under the standard virulence induction conditions and two of the relBE mutants displayed a colonization defect, which was not due to an effect on virulence gene expression. Although further studies are needed to characterize the mechanism of action, our study reveals that RelBE systems are important for V. cholerae physiology.     

An alternative classification of trypanorhynch cestodes considering the tentacular armature as being of limited importance

Based on a light- and scanning electron microscopical study of scolex morphology, tentacles and surface structures of 31 trypanorhynch species, an alternative classification of the trypanorhynch cestodes, adults, plerocerci and postlarvae, is presented. The arrangement of the tentacular armature is no longer used as a distinguishing feature for four different superfamilies. Instead, the presence or absence of ciliated pits and prebulbular organs is used to define three superfamilies: Tentacularioidea Poche, 1926; Otobothrioidea Dollfus, 1942; and Eutetrarhynchoidea Guiart, 1927. A total of 12 families are defined by the characters: the presence/absence of blastocysts, the number of bothridia and the reduction of the rhyncheal apparatus, together with a new character, complete rows of tentacular hooks (homeoacanth and heteroacanth typica) versus rows of hooks partly reduced (heteroacanth atypica and poeciloacanth). Of the 19 families previously accepted, 10 are retained (Eutetrarhynchidae, Gilquiniidae, Lacistorhynchidae, Mixodigmatidae, Otobothriidae, Paranybeliniidae, Pterobothriidae, Shirleyrhynchidae, Sphyriocephalidae and Tentaculariidae, all sensu nov.); one family is reinstated (i.e. Aporhynchidae Poche, 1926 sensu nov.) and a new one is added (i.e. Pseudotobothriidae n. fam.). Advantages of this alternative classification of trypanorhynch cestodes are: (i) the resolution of incongruities and questions caused by the use of the tentacular armature to distinguish superfamilies; (ii) the criteria for the establishment of higher taxa, superfamilies and families are clearly defined; (iii) with the findings of new species with different character combinations, this system can be enlarged up to 4 superfamilies and 48 families without loosing its stability; and (iv) all existing genera are easily re-assigned to the superfamilies and families.     

Nitrosothiol Formation and Protection against Fenton Chemistry by Nitric Oxide-induced Dinitrosyliron Complex Formation from Anoxia-initiated Cellular Chelatable Iron Increase

Dinitrosyliron complexes (DNIC) have been found in a variety of pathological settings associated with ^•NO. However, the iron source of cellular DNIC is unknown. Previous studies on this question using prolonged ^•NO exposure could be misleading due to the movement of intracellular iron among different sources. We here report that brief ^•NO exposure results in only barely detectable DNIC, but levels increase dramatically after 1–2 h of anoxia. This increase is similar quantitatively and temporally with increases in the chelatable iron, and brief ^•NO treatment prevents detection of this anoxia-induced increased chelatable iron by deferoxamine. DNIC formation is so rapid that it is limited by the availability of ^•NO and chelatable iron. We utilize this ability to selectively manipulate cellular chelatable iron levels and provide evidence for two cellular functions of endogenous DNIC formation, protection against anoxia-induced reactive oxygen chemistry from the Fenton reaction and formation by transnitrosation of protein nitrosothiols (RSNO). The levels of RSNO under these high chelatable iron levels are comparable with DNIC levels and suggest that under these conditions, both DNIC and RSNO are the most abundant cellular adducts of ^•NO.     

紫晶香蘑栽培生物学研究

紫晶香蘑栽培生物学研究卢成英，李鹄鸣，钟以举（湖南省吉首大学生态研究所４１６０００）ＢｉｏｌｏｇｉｃａｌＲｅｓｅａｒｃｈｏｎＬｅｐｉｓｔａｓｏｒｄｉｄａＣｕｌｔｉｖａｔｉｏｎ．￥Ｌｕｃｈｅｎｇｙｉｎｇ；ＬｉＨｕｍｉｎｇ；ＺｈｏｎｇＹｉｊｕ（Ｉｎ－ｓｔ...     

Rhesus macaques build new social connections after a natural disaster

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Negative regulation of AMPK signaling by high glucose via E3 ubiquitin ligase MG53

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