Photoperiodic,thermal and trophic responses of a predatory ladybird Cheilomenes propinqua

Large geographic range, wide habitat specificity and broad range of prey (including a number of pests of protected crops) suggest that a predatory ladybird Cheilomenes propinqua can be considered as potential agent for biological control in greenhouses. We investigated the influence of day length (10, 12 and 14 hr), temperature (20 and 24°C) and diet (the green peach aphid Myzus persicae and eggs of the grain moth Sitotroga cerealella) on the rate of maturation, fecundity and induction of reproductive diapause in C. propinqua females of a laboratory population originated from Alexandria, Egypt. The proportion of diapausing females (i.e. those with poorly developed ovaries and well-developed fat body) varied from 5% to 70% being higher at short day, low temperature and feeding on the grain moth eggs. This diapause, however, was not very stable: more than 20% of females kept under diapause-inducing conditions started to lay eggs during 110 days, although their pre-oviposition period was about 5 times longer than that of females which matured at the same temperature but at the long day and on the natural diet. Although not very stable, reproductive diapause significantly increased survival of starving females. Such a short-term reproductive diapause can be considered as an adaptation to mild and short-term subtropical winter. The results of our study suggest that C. propinqua mass rearing will be more intensive at the combination of high temperature, natural food (aphids) and long day (14 hr), whereas individuals intended for long-term storage should be reared under moderate temperature (20°C) and short-day (10 hr) conditions and should be fed on factitious food (the grain moth eggs).     

Directed and spontaneous disulfide bond closure using hydrogen peroxide in the synthesis of endothelins-1 and -3]

The linear precursors of endothelin 1 and endothelin 3, natural vasoactive peptides, were obtained by using the Boc- and Fmoc-schemes of solid phase peptide synthesis. The methods of directed and spontaneous formation of two disulfide bonds in the molecules of these precursors were compared and shown to give comparable results. The conditions were found that provided the selective S-S-ring closure in the methionine-containing endothelin 1 by means of hydrogen peroxide without the undesired conversion of the Met residue into the corresponding sulfoxide.     

On the methods of disinfecting bronchofibroscopes

An apparatus is proposed for the wet disinfection of bronchofibroscopes which enables to wash with disinfectant solution the external surfaces of the tube and instrument channel while keeping dry the control mechanism. Several disinfecting regimens have been tested using chlorohexidine (Gibitan), benzalkonium chloride (Roccal), diocide and ethanol solutions. On experimental contamination of bronchofibroscopes with a P. aeruginosa culture effective disinfection was achieved using 0.5% aqueous and ethanol solution of chlorohexidine and 1% benzalkonium chloride solution (5-min, exposure in the circulation mode of the apparatus), 0.1% solution of diocide only produced a bactericidal effect after a 30-min, exposure. Adequate disinfection was not feasible when the endoscope was soaked in disinfectant. Similar results were obtained when bronchofibroscopes were disinfected in a clinical setup where they became contaminated with the most common pathogenic and potentially pathogenic microflora from the airways of patients suffering from purulent pulmonary diseases.     

Interaction between hair cells in the statocyst ofHelix lucorum

An electrophysiological study of interactions between hair cells within the statocyst ofHelix lucorum was undertaken by intracellular and extracellular recording. Analysis of the results led to the following conclusions. First, some hair cells, subtending on angle on the arc of the statocyst sphere of not more than 90°, were electrically connected; electrical synapses, moreover, possessed polar properties; the coefficient of coupling in one direction was about 10 times greater than the other. Second, some connections between hair cells which subtended an angle of not more than 90° were mixed electrochemical in character. The excitatory chemical component in this case was directed in a direction opposite to effective electrical conduction. Third, inhibitory connections were observed between statocyst receptors: monosynaptic chemical (subtending an angle of about 180°, evidently, between the hair cells) and polysynaptic weak inhibitory interactions (subtending an angle in this case of not less than 90–100° between the test neurons). Fourth, all types of connection between hair cells were observed in CNS preparations with the vestibular nerve divided close to the cerebral ganglion. This means that zones of synaptic contacts between these receptors are located not in the CNS, but close to the statocyst.Institute of Higher Nervous Activity and Neurophysiology, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 17, No. 2, pp. 230–239, March–April, 1985.     

Structurally Mapping Endogenous Heme in the CcmCDE Membrane Complex for Cytochrome c Biogenesis

Although many putative heme transporters have been discovered, it has been challenging to prove that these proteins are directly involved with heme trafficking in vivo and to identify their heme binding domains. The prokaryotic pathways for cytochrome c biogenesis, Systems I and II, transport heme from inside the cell to outside for stereochemical attachment to cytochrome c, making them excellent models to study heme trafficking. System I is composed of eight integral membrane proteins (CcmA–H) and is proposed to transport heme via CcmC to an external “WWD” domain for presentation to the membrane-tethered heme chaperone, CcmE. Herein, we develop a new cysteine/heme crosslinking approach to trap and map endogenous heme in CcmC (WWD domain) and CcmE (defining “2-vinyl” and “4-vinyl” pockets for heme). Crosslinking occurs when either of the two vinyl groups of heme localize near a thiol of an engineered cysteine residue. Double crosslinking, whereby both vinyls crosslink to two engineered cysteines, facilitated a more detailed structural mapping of the heme binding sites, including stereospecificity. Using heme crosslinking results, heme ligand identification, and genomic coevolution data, we model the structure of the CcmCDE complex, including the WWD heme binding domain. We conclude that CcmC trafficks heme via its WWD domain and propose the structural basis for stereochemical attachment of heme.     

<Emphasis Type="Italic">Staphylococcus simulans</Emphasis> recombinant lysostaphin: Production,purification, and determination of antistaphylococcal activity

Staphylococcus simulans lysostaphin is an endopeptidase lysing staphylococcus cell walls by cleaving pentaglycine cross-bridges in their peptidoglycan. A synthetic gene encoding S. simulans lysostaphin was cloned in Escherichia coli cells, and producer strains were designed. The level of produced biologically active lysostaphin comprised 6-30% of total E. coli cell protein (depending on E. coli M15 or BL21 producer) under batch cultivation conditions. New methods were developed for purification of lysostaphin without affinity domains and for testing its enzymatic activity. As judged by PAGE, the purified recombinant lysostaphin is of >97% purity. The produced lysostaphin lysed cells of Staphylococcus aureus and Staphylococcus haemolyticus clinical isolates. In vitro activity and general biochemical properties of purified recombinant lysostaphin produced by M15 or BL21 E. coli strains were identical to those of recombinant lysostaphin supplied by SigmaAldrich (USA) and used as reference in other known studies. The prepared recombinant lysostaphin represents a potential product for development of enzymatic preparation for medicine and veterinary due to the simple purification scheme enabling production of the enzyme of high purity and antistaphylococcal activity.     

Rapid synthesis of long-chain deoxyribooligonucleotides by the N-methylimidazolide phosphotriester method.

A modified phosphotriester method has been employed for the efficient chemical synthesis of long-chain deoxyribooligonucleotides. During the course of this work, a general and rapid procedure was developed for the preparation of 24-62-mers in solution. Preparative reversed phase column chromatography on silanized silica gel was used to purify triester intermediates starting from 10-mers. The rapid synthesis of 32-mer and 42-mer on glass and silica gel supports using suitably protected 2-8-mer blocks as coupling units has been also accomplished. In particular, a convenient procedure for the solid-phase synthesis of oligonucleotide blocks bearing 3'-terminal phosphodiester groups is described.     

Interaction of eukaryotic threonyl-tRNA synthetase with high-Mr RNAs and tRNA(Thr)

Threonyl-tRNA synthetase of rabbit reticulocytes was purified to homogeneity. We have found that this enzyme can interact not only with cognate tRNA(Thr), but also with high-Mr RNAs. tRNA(Thr) removes rRNA from the complexes with threonyl-tRNA synthetase. On the other hand, rRNA is unable to dissociate tRNA(Thr) from the complexes with the enzyme. Despite its dimeric organization, threonyl-tRNA synthetase is unable to form stable ternary complexes with tRNA(Thr) and rRNA. In the extract of rabbit reticulocytes about one-third of the threonyl-tRNA synthetase molecules are in association with cognate tRNA(Thr) and thus are unable to interact with high-Mr RNAs.