Comparative study of the karyotypes of two Egyptian species of bats,Taphozous perforatus andTaphozous nudiventris (Chiroptera: Mammalia)

A detailed karyotypic analysis of two Egyptian species of bats,Taphozous perforatus andTaphozous nudiventris, was made on the basis of conventional data and G-band patterns. No detectable karyotypic difference was found between the two species (2n=42, F.N. 64). By comparison of G-band patterns, some differences between the two species were seen in the corresponding autosomal pairs. These results are reported for the first time in Egypt.     

伊朗青蜂科和切叶蜂科种类（膜翅目：青蜂总科，蜜蜂总科）

本文记述了伊朗膜翅目Hymenoptera青蜂科Chrysididae和切叶蜂科MegachiLidae的种类，其中青蜂科7属（ Chrysis，Chrysura，Cleptes，Pseudomalus，Trichrysis，Parnopes和Spinolia）10种，切叶蜂科10属（ Anthidium， Anthidiellum，Chalicodoma，Coelioxys，Heriades，Hoplitis，Megachile，Osmia，Protosmia 和Stelis）17种。     

The role of key residues in structure, function, and stability of cytochrome-c

Cytochrome-c (cyt-c), a multi-functional protein, plays a significant role in the electron transport chain, and thus is indispensable in the energy-production process. Besides being an important component in apoptosis, it detoxifies reactive oxygen species. Two hundred and eighty-five complete amino acid sequences of cyt-c from different species are known. Sequence analysis suggests that the number of amino acid residues in most mitochondrial cyts-c is in the range 104?±?10, and amino acid residues at only few positions are highly conserved throughout evolution. These highly conserved residues are Cys14, Cys17, His18, Gly29, Pro30, Gly41, Asn52, Trp59, Tyr67, Leu68, Pro71, Pro76, Thr78, Met80, and Phe82. These are also known as “key residues”, which contribute significantly to the structure, function, folding, and stability of cyt-c. The three-dimensional structure of cyt-c from ten eukaryotic species have been determined using X-ray diffraction studies. Structure analysis suggests that the tertiary structure of cyt-c is almost preserved along the evolutionary scale. Furthermore, residues of N/C-terminal helices Gly6, Phe10, Leu94, and Tyr97 interact with each other in a specific manner, forming an evolutionary conserved interface. To understand the role of evolutionary conserved residues on structure, stability, and function, numerous studies have been performed in which these residues were substituted with different amino acids. In these studies, structure deals with the effect of mutation on secondary and tertiary structure measured by spectroscopic techniques; stability deals with the effect of mutation on T _m (midpoint of heat denaturation), ?G _D (Gibbs free energy change on denaturation) and folding; and function deals with the effect of mutation on electron transport, apoptosis, cell growth, and protein expression. In this review, we have compiled all these studies at one place. This compilation will be useful to biochemists and biophysicists interested in understanding the importance of conservation of certain residues throughout the evolution in preserving the structure, function, and stability in proteins.     

Variant Computer Aided Process Planning System for Rotational Parts

Introduction Processplanningisafunctionthatestablishesthe machiningprocesses,machinesandtoolingcapableof performingtheseprocesses,andmachiningparametersto beusedtoconvertapiecepartfromitsinitialformtoa predeterminedshape,aspertheengineeringdrawing.Approaches usedforcomputeraidedprocessplanning(CAPP)canbe classifiedasVariant,GenerativeorhybridSemi generative.In thevariantapproach,aprocessplanfornewcomponent createdbyretrievingastandardplanthathasbeenstoredin thedatabase,usinggrouptechnologyc…     

先进高强钢DP590焊缝的组织特征和力学性能改善

The effects of the welding current mode in resistance spot welding on the microstructure and mechanical properties of advanced high-strength steel dual-phase 590 (DP590) sheets were investigated. Results showed that a rough martensitic structure was formed in the weld zone of the sample welded via the single-pulsed mode, whereas the microstructure in the heat-affected zone consisted of a very rough martensitic microstructure and rough ferrite. However, using the secondary pulse mode led to the formation of tempered martensite in the weld zone. The maximum load and the energy absorption to failure of the samples with the secondary pulsed cycle were higher than those of the samples with the single-pulsed mode. Tensile shear results indicated that the secondary pulsed mode could significantly change the mode of failure upon shear tension testing. Therefore, the obtained results suggest that the use of secondary pulsed mode can improve the microstructural feature and mechanical properties of advanced high-strength steel DP590 welds.     

Inhibition of methanol metabolism in mice with acetyl salicylic acid

Zusammenfassung Acetylsalicylsäure hemmt die Oxydation von Methanol und Formiat in vivo erheblich, die Katalase nur in vitro, und vermindert den toxischen Effekt der Methanolvergiftung. Der Mechanismus der Methanoloxydationshemmung durch Acetylsalicylsäure könnte eher auf die Verminderung des Peroxyd-Pooles — als die Katalasehemmung — zurückzuführen sein.     

Chronic lymphocytic leukaemia is driven by antigen-independent cell-autonomous signalling

B-cell antigen receptor (BCR) expression is an important feature of chronic lymphocytic leukaemia (CLL), one of the most prevalent B-cell neoplasias in Western countries. The presence of stereotyped and quasi-identical BCRs in different CLL patients suggests that recognition of specific antigens might drive CLL pathogenesis. Here we show that, in contrast to other B-cell neoplasias, CLL-derived BCRs induce antigen-independent cell-autonomous signalling, which is dependent on the heavy-chain complementarity-determining region (HCDR3) and an internal epitope of the BCR. Indeed, transferring the HCDR3 of a CLL-derived BCR provides autonomous signalling capacity to a non-autonomously active BCR, whereas mutations in the internal epitope abolish this capacity. Because BCR expression was required for the binding of secreted CLL-derived BCRs to target cells, and mutations in the internal epitope reduced this binding, our results indicate a new model for CLL pathogenesis, with cell-autonomous antigen-independent signalling as a crucial pathogenic mechanism.