Mutation of the matrix metalloproteinase 2 gene (MMP2) causes a multicentric osteolysis and arthritis syndrome.

The inherited osteolyses or 'vanishing bone' syndromes are a group of rare disorders of unknown etiology characterized by destruction and resorption of affected bones. The multicentric osteolyses are notable for interphalangeal joint erosions that mimic severe juvenile rheumatoid arthritis (OMIMs 166300, 259600, 259610 and 277950). We recently described an autosomal recessive form of multicentric osteolysis with carpal and tarsal resorption, crippling arthritic changes, marked osteoporosis, palmar and plantar subcutaneous nodules and distinctive facies in a number of consanguineous Saudi Arabian families. We localized the disease gene to 16q12-21 by using members of these families for a genome-wide search for homozygous-by-descent microsatellite markers. Haplotype analysis narrowed the critical region to a 1.2-cM region that spans the gene encoding MMP-2 (gelatinase A, collagenase type IV; (ref. 3). We detected no MMP2 enzymatic activity in the serum or fibroblasts of affected family members. We identified two family-specific homoallelic MMP2 mutations: R101H and Y244X. The nonsense mutation effects a deletion of the substrate-binding and catalytic sites and the fibronectin type II-like and hemopexin/TIMP2 binding domains. Based on molecular modeling, the missense mutation disrupts hydrogen bond formation within the highly conserved prodomain adjacent to the catalytic zinc ion.     

分子间作用力对制备含有机废弃之水泥浆体影响研究

研究以水泥处理固体有机物时，有机物对水泥水化的影响。以膜流模式说明水份在水泥浆体内传输的现象。水膜存在半干之水泥浆体，其厚度小于100nm，膜流由离分压所驱动，而离分压来自分子间作用力。膜拟结果发现，水泥浆体内局部位置可用以进行水化之水量为Q=-Aslv／6vπ。当有机物添加在水泥浆体内时，会影响Hamaker常数，Aslv因此可能使膜流不稳定或完全抑制膜流，因而使水泥浆体内局部缺水，影响水化进行，造成成品强度降低，影响品质。     

Fecundity of the blood-feeding insectRhodnius prolixus increases in successive periods of egg production

The fecundity of the blood-feeding insect,Rhodnius prolixus, was observed to increase in successive periods of egg production, each period being triggered by a single large blood meal. As previously published, the fecundity of mated animals was significantly higher than that of unmated animals for the first period of egg production. For a second period of egg production, fecundity increased significantly in both mated and unmated animals. By the fourth period, fecundity had returned to first-feed values for mated animals, but remained high for unmated animals, and the fecundity of mated and unmated animals was not significantly different. Thus, during successive periods of egg production, the processes which maintain fecundity of unmated animals below that of mated animals are overcome.     

Induction of hemopoietic chimerism in the caprine fetus by intraperitoneal injection of fetal liver cells

Summary Intraperitoneal injection of allogeneic liver cells from 43-day-old male fetuses into normal 60-day female goat fetuses resulted in persistent hemopoietic chimerism in surviving recipients without clinical evidence of graft-versus-host disease. Transplantation of normal fetal liver cells into preimmunocompetent goat fetuses affected with -D-mannosidosis may provide an alternative strategy for evaluating hemopoietic stem cell transplantation in the treatment of human lysosomal storage diseases.     

Changes in glycosaminoglycan sulfation and protein kinase C subcellular distribution during differentiation of the human colon tumor cell line Caco-2

Summary During the spontaneous differentiation (day 5 to day 15 of the culture) of Caco-2 cells, the sulfation of cell layer glycosaminoglycans increased, whereas protein kinase C activity was concomitantly redistributed from the membrane to the cytosol. The protein kinase C activators, 4-phorbol 12-myristate, 13-acetate and 1,2-dioctanoyl-glycerol inhibited glycosaminoglycan sulfation. By contrast, 4-phorbol 12, 13 didecanoate was ineffective.These results suggest that membrane-bound PKC may exert a modulatory effect on glycosaminoglycan sulfation, and this effect is gradually attenuated as Caco-2 cell differentiation progresses.     

Chemical ecology of oviposition in phytophagous insects

Summary Selection of a suitable site for oviposition by phytophagous insects is critical for successful development of the offspring. The behavioral events leading to oviposition are mediated to a large extent by chemical cues associated with potential host plants. Orientation and landing are primarily guided by volatile constituents of a plant, whereas assessment of a leaf surface depends on contact stimuli. Chemical mechanisms that ensure adequate spacing of progeny on limited resources include the production of oviposition-deterring pheromones as well as recognition of plant constituents released as a result of previous damage. Perception of chemical cues that affects oviposition involves receptors on antennae, tarsi, mouthparts or the ovipositor. Complex behavior such as tarsal drumming or stem runs may serve to provide increased receptor contact with chemical stimuli. Abiotic and biotic environmental factors often influence the production or release of behavior-modifying chemicals by a plant, and therefore affect oviposition preferences. Plant chemistry may be involved in associative learning, but may also lead to mistakes. Thus a clear correlation between oviposition preference and offspring success does not always exist.     

Failure of opioids to affect excitation and contraction in isolated ventricular heart muscle

Summary The opioid agonists morphine (selective for -receptors) and ethylketocyclazocine (selective for kappa-receptors), at concentrations evoking strong effects in neuronal structures, did not significantly affect the configuration of the intracellularly recorded action potential and the force of contraction in ventricular heart muscle isolated from guinea pigs, rabbits and man. These results suggest that any changes of heart functions in vivo in response to opioid-like drugs are probably not mediated postsynaptically at the myocardial cell membrane but rather presynaptically, influencing the release of noradrenaline and/or acetylcholine from the nerve terminals.     

Evidence for anoxygenic photosynthesis from the distribution of bacteriochlorophylls in the Black Sea

The contribution of anoxygenic photosynthesis to carbon cycling in the Black Sea, the world's largest body of anoxic marine water, has been vigorously investigated and debated for over four decades. Penetration of light into the sulphide-containing deep water may result in a zone of anaerobic primary production by photosynthetic bacteria. We report here the results of analyses of photosynthetic pigments in samples of suspended particulate matter collected from two stations in the western basin of the Black Sea. Our data demonstrate high concentrations of a bacterio-chlorophyll at the chemocline, and thus the potential for anoxygenic photosynthesis as a component of primary production in the carbon cycle of the Black Sea. More than 95% of the pigments in the bacteriochlorophyll-maximum are accounted for by a series of aromatic carotenoids and bacteriochlorophylls-e, including a previously unreported geranyl ester of 4-i-butyl bacteriochlorophyll-e. The distribution of pigments is characteristic of the obligate phototrophs Chlorobium phaeobacteroides and C. phaeovibriodes. Total depth-integrated bacteriochlorophyll at one station exceeded total chlorophyll-a in the overlying oxygenated portion of the euphotic zone. We suggest that anoxygenic photosynthesis is a relatively recent phenomenon in the Black Sea initiated by shallowing of the chemocline over the past decade and development of an anoxic layer devoid of O2 and H2S.     

New window on Proterozoic life

This article briefly discusses the the new fossil assemblage found in the 600-650-million-year-old shales of the Pertatataka formation in central Australia. It includes about two dozen taxa of spinose, process-bearing or otherwise ornamented acritarchs, many of them extremely large relative to comparably ornamented fossils in younger rocks. These acritarchs reveal a glimpse of early evolution and Proterozoic life.     

Comments on “aggregation of equivalence relations” by P. C. Fishburn and A. Rubinstein

The theorem of the paper Aggregation of Equivalence Relations, by Fishburn and Rubinstein, states a result already known. This theorem improves a result from Mirkin (1975) and appears as a corollary occurring in Leclerc (1984).

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Resume L'unique théorème de l'article Aggregation of Equivalence Relations de Fishburn et Rubinstein est déja connu. Il améliore, en fait, un résultat de Mirkin (1975) et apparait en tant que corollaire dans Leclerc (1984).