Meiosis: role of a histone kinase in the condensation of ovarian oocyte chromosomes of Xenopus laevis and Ambystoma mexicanum]

By injecting heterologous histone-kinase preparations into ovarian Axolotl oocytes, it has been possible to speed up the progesterone-induced process of chromosome condensation. Moreover, in some instances, this condensation and even complete maturation have been obtained after injection of protein kinase alone, thus in the absence of hormone stimulation. Two different histone kinase preparations have been used: one was prepared from ascites cell chromatin and the other from in vitro ovulated Xenopus oocytes.     

Influence of nitrogen components of wine on the growth of lactic acid bacteria]

Three different fractions of nitrogen compounds have been extracted from wine: proteins, peptides, amino acids. They have been tested to support the growth of malolactic bacteria in acid medium: only the peptidic fraction supports this growth.     

Lipoxygenase activity of wheat seeding chloroplasts]

Chloroplasts have been isolated from Wheat shoots by density gradient centrifugation. When added to a linoleic acid and Tween 20 suspension these chloroplasts induce an oxygen consumption. The hydroperoxides synthesized from linoleic and oxygen have been characterized by spectrophotometry and thin layer chromatography.     

Isolation and amino acid compositions of geographutoxin I and II from the marine snail Conus geographus

The peptide toxins having inhibitory effects on the contractile response of the mouse diaphragm to direct stimulation, geographutoxin I and II, have been isolated from Conus geographus, and their amino acid compositions have been determined.     

Molecular parasitology: progress towards the development of vaccines for malaria, filariasis, and schistosomiasis

Advances in molecular biology have allowed for the identification of potential vaccine candidates against several parasitic diseases. Antigens from various life stages of Plasmodium and Schistosoma species and filarial worms have been cloned, sequenced and tested as vaccines. Results to date in animal models have been promising. Modest levels of protection against experimental human malaria have been obtained using both sporozoite and blood-stage antigens. However, a greater understanding of the mechanisms which lead to immunity against parasites is required before effective vaccines can be developed.     

Undulating tubules in lymphocytes of an apparently healthy human donor.

So-called 'undulating tubules' were found in the blood lymphocytes of an apparently healthy 33-year-old male. Undulating tubules have been noted to occur frequently in kidney cells and blood lymphocytes of patients suffering from collagen diseases and especially from SLE. They have been suggested to be a possibly pathognomonic finding in such diseases. Our result seems to contradict such an association.     

Recent structural studies of carbohydrate-binding modules

Carbohydrate-binding modules (CBMs) are found in many carbohydrate-active enzymes. CBMs bind to a range of polysaccharides, their primary function being to increase the catalytic efficiency of the carbohydrate-active enzymes against soluble and/or insoluble substrates. CBMs bind to their target ligands with high specificities and affinities. Thus, CBM systems are excellent models to study the mechanism of protein-carbohydrate interaction. To date, CBMs have been classified into 45 different families and many structural and functional studies have been reported. At present, three-dimensional structures of CBMs from 31 different families have been determined. These structures demonstrate that the fold most commonly found in CBMs is the β-sandwich. In the past few years, about 10 new structures from different families have been reported. These enable detailed classification of CBM structures. This article reviews recent structural and functional studies of CBMs and discusses the sub-classification of β-sandwich CBMs. Received 28 April 2006; received after revision 12 July 2006; accepted 14 September 2006     

Function and evolution of channels and transporters in photosynthetic membranes

Chloroplasts from land plants and algae originated from an endosymbiotic event, most likely involving an ancestral photoautotrophic prokaryote related to cyanobacteria. Both chloroplasts and cyanobacteria have thylakoid membranes, harboring pigment-protein complexes that perform the light-dependent reactions of oxygenic photosynthesis. The composition, function and regulation of these complexes have thus far been the major topics in thylakoid membrane research. For many decades, we have also accumulated biochemical and electrophysiological evidence for the existence of solute transthylakoid transport activities that affect photosynthesis. However, research dedicated to molecular identification of the responsible proteins has only recently emerged with the explosion of genomic information. Here we review the current knowledge about channels and transporters from the thylakoid membrane of Arabidopsis thaliana and of the cyanobacterium Synechocystis sp. PCC 6803. No homologues of these proteins have been characterized in algae, although similar sequences could be recognized in many of the available sequenced genomes. Based on phylogenetic analyses, we hypothesize a host origin for most of the so far identified Arabidopsis thylakoid channels and transporters. Additionally, the shift from a non-thylakoid to a thylakoid location appears to have occurred at different times for different transport proteins. We propose that closer control of and provision for the thylakoid by products of the host genome has been an ongoing process, rather than a one-step event. Some of the proteins recruited to serve in the thylakoid may have been the result of the increased specialization of its pigment-protein composition and organization in green plants.     

Chromatographic fractionation and studies on microheterogenity of cow lactotransferrin prepared by an original procedure]

Authors describe an original procedure to prepare pure lactotransferrin from cow milk. Physicochemical properties of this lactotransferrin have been studied and compared with results from others. New data are presented: presence of fucose and N-acetylgalactosamine; C-terminal amino-acid identified with threonine. On the other hand, 4 fractions have been obtained by "DEAE-Sephadex" chromatography, study of which demonstrates that the microheterogeneity of the lactotransferrin depends on the carbohydrate moiety and especially on the N-acetylneuraminic acid content which varies from 0 to 2 residues.     

New bibenzyls of the liverwort,Radula variabilis

Summary 3 new bibenzyls having a 7-membered heterocyclic ring have been isolated from the liverwort,Radula variabilis and their structures have been established to be1, 3 and5.     

Gap junctions in myo-endothelial bridges of rabbit carotid arteries

Summary Myo-endothelial contacts have been studied in rabbit carotid arteries. Structures, featuring as gap junctions, have been depicted by means of lanthanum hydroxide.Acknowledgment. This work has been partly supported by grants Nos 78.00571.83 and 76.01561.04 from Italian CNR.     

Molecular parasitology: Progress towards the development of vaccines for malaria,filariasis, and schistosomiasis

Summary Advances in molecular biology have allowed for the identification of potential vaccine candidates against several parasitic diseases. Antigens from various life stages ofPlasmodium andSchistosoma species and filarial worms have been cloned, sequenced and tested as vaccines. Results to date in animal models have been promising. Modest levels of protection against experimental human malaria have been obtained using both sporozoite and blood-stage antigens. However, a greater understanding of the mechanisms which lead to immunity against parasites is required before effective vaccines can be developed.     

Chemical components of the rectal gland secretions of maleDacus cucurbitae,the melon fly

Summary The volatile constituents of the rectal gland secretion of maleDacus cucurbitae have been shown to contain 2-methoxy-N-3-methylbutyl acetamide together with 2 other amides, 3 pyrazine derivatives and 2-ethoxybenzoic acid. Excised male rectal glands have been demonstrated to elicit strong responses from female melon flies.Acknowledgment. We thank Dr P. Howse for valuable discussions and advice.     

Nerve endings isolated from chick embryonic optic tectum. 1. Developmental aspects of intact synaptosomes

Summary Fractions enriched in nerve endings (synaptosomes) have been isolated from optic tectum of chick embryos at 16 and 18 days of incubation and of chicks immediately after hatching. Morphological aspects of nerve endings have been examined with special regard to the appearance of synaptic thickenings and synaptic vesicles.     

Primordial chemistry and enzyme evolution in a hot environment

Ever since the publication of Darwin’s Origin of Species, questions have been raised about whether enough time has elapsed for living organisms to have reached their present level of complexity by mutation and natural selection. More recently, it has become apparent that life originated very early in Earth’s history, and there has been controversy as to whether life originated in a hot or cold environment. This review describes evidence that rising temperature accelerates slow reactions disproportionately, and to a much greater extent than has been generally recognized. Thus, the time that would have been required for primordial chemistry to become established would have been abbreviated profoundly at high temperatures. Moreover, if the catalytic effect of a primitive enzyme (like that of modern enzymes) were to reduce a reaction’s heat of activation, then the rate enhancement that it produced would have increased as the surroundings cooled, quite aside from changes arising from mutation (which is itself highly sensitive to temperature). Some nonenzymatic catalysts of slow reactions, including PLP as a catalyst of amino acid decarboxylation, and the Ce^IV ion as a catalyst of phosphate ester hydrolysis, have been shown to meet that criterion. The work reviewed here suggests that elevated temperatures collapsed the time required for early evolution on Earth, furnishing an appropriate setting for exploring the vast range of chemical possibilities and for the rapid evolution of enzymes from primitive catalysts.     

Identification and localization of volatile hairpencil components in maleAmauris ochlea butterflies (Danaidae)

Summary By gas-chromatography and mass-spectroscopy 7 volatile substances have been found on the abdominal hairpencils ofAmauris ochlea males. 6 substances have been identified. The spatial distribution of compounds is correlated to the 5 types of hairs comprising the scent organ.Acknowledgments. We thank our colleagues M. Kaib and P. Lounibos for their continous effort to supply us with danaids from Kenya. Support by a research grant from the National Institute of Health (AI 12020) is acknowledged with pleasure.     

突发性地质灾害研究现状

近年来,突发性地质灾害的频繁发生,给人们的生命财产造成的损失越来越大,对突发性地质灾害的研究已经成为国际社会关注的热点领域.为了及时总结该领域已有的研究成果,为防灾减灾提供科学依据,本文从对突发性地质灾害的成因、危险性评价、预测预警和防治等方面进行了现状综述,分析讨论了突发性地质灾害及防治存在的问题与进一步研究的方向.     

Recent results on hydrogen and hydration in biology studied by neutron macromolecular crystallography

Neutron diffraction provides an experimental method of directly locating hydrogen atoms in proteins, a technique complimentary to ultra-high-resolution [1, 2] X-ray diffraction. Three different types of neutron diffractometers for biological macromolecules have been constructed in Japan, France and the United States, and they have been used to determine the crystal structures of proteins up to resolution limits of 1.5-2.5 A. Results relating to hydrogen positions and hydration patterns in proteins have been obtained from these studies. Examples include the geometrical details of hydrogen bonds, H/D exchange in proteins and oligonucleotides, the role of hydrogen atoms in enzymatic activity and thermostability, and the dynamical behavior of hydration structures, all of which have been extracted from these structural results and reviewed. Other techniques, such as the growth of large single crystals, the preparation of fully deuterated proteins, the use of cryogenic techniques, and a data base of hydrogen and hydration in proteins, will be described.     

Mushroom toxins of the genusCortinarius

Summary 3 major components of the toxic fungusCortinarius speciosissimus have been isolated and their structures determined as cyclic polypeptides. 2 of these compounds have been shown in laboratory animals to cause nephrotoxicity characteristic of Cortinarius mushroom poisoning.The work was carried out with support from the Scottish Home and Health Department grant No. K/MRS/50/C350 and the Science and Engineering Research Council.