Unexpected twist to the Z ring

Development in Bacillus subtilis involves a switch in the location of the cytokinetic Z ring from midcell to the pole. Time lapse photography of an FtsZ-GFP fusion reveals that this switch involves a spiral intermediate and allows identification of the specific sporulation functions involved.     

Plant cell cycle: cellularisation of the endoderm needs spätzle

Early development of the endosperm of flowering plants involves the formation of a syncytium through successive rounds of nuclear division without cell wall synthesis. New data reveal that cellularisation of this syncytium requires the SPATZLE protein and involves the formation of cell walls similar to those of somatic tissues.     

植物细胞中钙信号的时空多样性与信号转导

近年来,对钙信号的研究,包括对钙信号的产生,传导及最终靶蛋白的研究,越来越受到人们的重视,植物生长发育过程的信息传递,包括对各种内外刺激的反应都涉及到钙信号,钙信号的产生及传导是通过胞质自由钙离子的浓度变化来实现的,本文综述了胞质自由钙离子的测定,钙信号的时空多样性及钙信号的靶蛋白如CaM,Ca^2 依赖的蛋白激酶,钙调磷酸酶,磷脂酰肌醇－磷脂酶C等方面的一些最新进展,展望了今后钙信号研究的方向所用到的一些技术方法等。     

植物细胞中钙信号的时空多样性与信号转导

近年来,对钙信号的研究,包括对钙信号的产生、传导及最终靶蛋白的研究,越来越受到人们的重视。植物生长发育许多过程的信息传递,包括对各种内外刺激的反应都涉及到钙信号。钙信号的产生及传导是通过胞质自由钙离子的浓度变化来实现的。本文综述了胞质自由钙离子的测定、钙信号的时空多样性及钙信号的靶蛋白如CaM、Ca2+依赖的蛋白激酶、钙调磷酸酶、磷脂酰肌醇_磷脂酶C 等方面的一些最新进展,展望了今后钙信号研究的方向及所用到的一些技术方法等。     

The 'NIH-Shift' during aromatic ortho-hydroxylation in higher plants

By feeding ortho-³H cinnamic acid to Melilotus and ortho-³H cinnamic and benzoic acids to Gaultheria it has been shown that ortho-coumaric acid biosynthesis involves an efficient migration and retention of the ortho proton while salicylic acid biosynthesis involves a much lower retention.     

Deactivation model involving a grace period for immobilized and soluble enzymes

A first-order deactivation model which involves a grace period is shown to fit reasonably well to the data presented for immobilized and soluble enzyme deactivation. The model involves the existence of a step that does not destroy enzyme activity as a compulsory precursor of the step that does. Two types of cases are presented in which the deactivation rate coefficient may or may not increase with time.     

Novel microbial nitrogen removal processes

The present-day wastewater treatment practices can be significantly improved through the introduction of new microbial treatment technologies. Recently, several new processes for nitrogen removal have been developed. These new nitrogen removal technologies provide practicable options for treating nitrogen-laden wastewaters. The new processes are based on partial nitrification of ammonium to nitrite combined with anaerobic ammonium oxidation. These processes include the single reactor system for high ammonia removal over nitrite (SHARON) process, which involves part conversion of ammonium to nitrite; the anaerobic ammonium oxidation (ANAMMOX) process, which involves anaerobic ammonium oxidation; and the completely autographic nitrogen removal over nitrite (CANON) process, which involves nitrogen removal within one reactor under oxygen-limited conditions. These new processes target the removal of nitrogen from wastewaters containing significant quantities of ammonium.     

Bacterial Degradation Products of the lxodicide Amitraz

The nature and order of appearance of the degradation products of amitraz by mixed bacterial cultures were investigated. The primary pathway involves the conversion of amitraz to 2,4-dimethylaniline. A slower secondary pathway involves the conversion of amitraz to 2,4-dimethylaniline via the intermediates N -2, 4-dimethylphenyl- N '-methylformamidine and 2, 4-dimethylformanilide. The bacterial degradation pathway of amitraz differs from that found in plants and animals.     

Polarity establishment requires localized activation of Cdc42

Establishment of cell polarity in animal and fungal cells involves localization of the conserved Rho-family guanosine triphosphatase, Cdc42, to the cortical region destined to become the “front” of the cell. The high local concentration of active Cdc42 promotes cytoskeletal polarization through various effectors. Cdc42 accumulation at the front is thought to involve positive feedback, and studies in the budding yeast Saccharomyces cerevisiae have suggested distinct positive feedback mechanisms. One class of mechanisms involves localized activation of Cdc42 at the front, whereas another class involves localized delivery of Cdc42 to the front. Here we show that Cdc42 activation must be localized for successful polarity establishment, supporting local activation rather than local delivery as the dominant mechanism in this system.     

Pattern formation in epithelial development: the vertebrate limb and feather bud spacing.

The ectoderm of the vertebrate limb and feather bud are epithelia that provide good models for epithelial patterning in vertebrate development. At the tip of chick and mouse limb buds is a thickening, the apical ectodermal ridge, which is essential for limb bud outgrowth. The signal from the ridge to the underlying mesoderm involves fibroblast growth factors. The non-ridge ectoderm specifies the dorsoventral pattern of the bud and Wnt7a is a dorsalizing signal. The development of the ridge involves an interaction between dorsal cells that express radical fringe and those that do not. There are striking similarities between the signals and genes involved in patterning the limb ectoderm and the epithelia of the Drosophila imaginal disc that gives rise to the wing. The spacing of feather buds involves signals from the epidermis to the underlying mesenchyme, which again include Wnt7a and fibroblast growth factors.     

Interactions between rotavirus and gastrointestinal cells

Rotaviruses are the leading cause of life-threatening diarrheal disease in infants and in young animals worldwide. The outcome of rotavirus infection of intestinal epithelial cells is more complex and involves induction of more diverse cellular responses than initially appreciated. Similar to bacteria, the pathogenesis of rotavirus-induced disease involves an enterotoxin, activation of the enteric nervous system and malabsorption, suggesting that common mechanisms of pathogenesis may exist between viral and bacterial pathogens.     

Comparison of two HPLC techniques for monitoring enantioselective reactions for the resolution of (R,S)-ibuprofen: Chiral HPLC vs achiral HPLC linked to an optical rotation detector

Two approaches have been used to monitor the enantioselective esterification of (R,S)-ibuprofen with 1-dodecanol catalyzed by Novozym 435. The first approach involves the use of a chiral column (Chiralcel OD) connected to a UV detector. The second approach involves using a C-18 reversed-phase column connected in series to a RI detector and to an Optical Rotation detector. The two methods yield the same results.     

Light-induced electron transfer in porphyrin-calixarene conjugates.

The fluorescence from a set of porphyrin-calixarene complexes is quenched upon addition of benzo-1,4-quinone (BQ) in fluid solution. In N,N-dimethylformamide solution, fluorescence quenching involves both static and dynamic interactions but there are no obvious differences between porphyrins with or without the appended calixarene. Under such conditions, the static quenching behaviour is attributed to pi-complexation between the reactants and it is concluded that the calixarene cavity does not bind BQ. An additional static component is apparent in dichloromethane solution. This latter effect involves partial fluorescence quenching, for which the intramolecular rate constant can be obtained by time-resolved fluorescence spectroscopy. The derived rate constants depend on molecular structure in a manner consistent with fluorescence quenching being due to electron transfer. In all cases, however, the dominant quenching step involves diffusional contact between the porphyrin nucleus and a non-bound molecule of BQ.     

Evolution and progress

The concept of progress is one which makes evolutionists feel very uneasy, yet it is also a concept to which they are forever returning. It is useful to make a distinction between 'comparative progress' which involves competition between groups, and 'absolute progress' which involves the climb up some objective scale. Both kinds of progress have been the subject of much debate in recent years, leading one to turn from expectations that the controversy will ever be resolved to queries about why it continues to obsess so many people.     

ASCENDING AORTIC ANEURYSM RESECTION EIGHT MONTHS AFTER TRIPLE CORONARY ARTERY BYPASS: CASE REPORT

This report involves the surgical treatment of a patient who underwent saphenous vein triple coronary artery bypass and subsequently developed an ascending aortic aneurysm and aortic insufficiency. Although the implantation of vascular structures into synthetic grafts is commonplace, this case is unique in that it involves the successful implantation of an aortic island containing the origin of the coronary arteries.     

Ionic bonding, the mechanism of viral uptake by shellfish mucus.

An investigation was conducted to determine the processes involved in the contamination of shellfish by viruses. Results of binding-release studies show that the process involves the attachment of viruses to mucus secreted, and then ingested, by shellfish during feeding. Analysis of the mucus-virus bond involved selective degradation of the mucus and use of chemical agents to block carboxyl and sulfate groups on the mucus. Results obtained indicate that the attachment of virus to mucus is primarily ionic and involves the binding of viral particles to sulfate radicals on the mucopolysaccharide moiety of shellfish mucus.     

Ionic bonding, the mechanism of viral uptake by shellfish mucus.

An investigation was conducted to determine the processes involved in the contamination of shellfish by viruses. Results of binding-release studies show that the process involves the attachment of viruses to mucus secreted, and then ingested, by shellfish during feeding. Analysis of the mucus-virus bond involved selective degradation of the mucus and use of chemical agents to block carboxyl and sulfate groups on the mucus. Results obtained indicate that the attachment of virus to mucus is primarily ionic and involves the binding of viral particles to sulfate radicals on the mucopolysaccharide moiety of shellfish mucus.