Association of marine archaea with the digestive tracts of two marine fish species

Recent studies have shown that archaea which were always thought to live under strict anoxic or extreme environmental conditions are also present in cold, oxygenated seawater, soils, the digestive tract of a holothurian deep-sea-deposit feeder, and a marine sponge. In this study, we show, by using PCR-mediated screening in other marine eukaryotes, that marine archaea are also present in the digestive tracts of flounder and grey mullet, two fish species common in the North Sea, in fecal samples of flounder, and in suspended particulate matter of the North Sea water column. No marine archaea could be detected in the digestive tracts of mussels or the fecal pellets of a copepod species. The archaeal 16S ribosomal DNA clone libraries of feces of flounder and the contents of the digestive tracts of grey mullet and flounder were dominated by group II marine archaea. The marine archaeal clones derived from flounder and grey mullet digestive tracts and feces formed a distinct cluster within the group II marine archaea, with 76.7 to 89. 8% similarity to previously described group II clones. Fingerprinting of the archaeal community of flounder digestive tract contents and feces by terminal restriction fragment length polymorphism of archaeal 16S rRNA genes after restriction with HhaI showed a dominant fragment at 249 bp, which is likely to be derived from group II marine archaea. Clones of marine archaea that were closely related to the fish-associated marine archaea clones were obtained from suspended particulate matter of the water column at two stations in the North Sea. Terminal restriction fragment length polymorphism fingerprinting of the archaeal community present in suspended particulate matter showed the same fragment pattern as was found for the archaeal community of the flounder digestive tract contents and feces. These data demonstrate that marine archaea are present in the digestive tracts and feces of very common marine fish. It is possible that the marine archaea associated with the digestive tracts of marine fish are liberated into the water column through the feces and subsequently contribute to the marine archaeal community of suspended particulate matter.     

The visual fields of American horseshoe crabs: two different eye shapes in Limulus polyphemus

The optical alignment of individual cuticular cones in the dioptric array of the lateral eye of Limulus polyphemus was determined with a precision two-circle goniometer constructed and mounted to the stage of a compound microscope and using a new formaldehyde-induced fluorescence procedure. All measurements were made from the corneal surface of the excised eye mounted in seawater through an air/water interface perpendicular to the optic axis of the microscope. Our results revealed two variants of visual field and eye curvature which can actually be discriminated in casual examination of adult animals. We call animals possessing these two variants "morlocks" and "eloi." Adult male and female morlocks about 25 cm across the carapace have eyes which are relatively elongated, often darker in pigmentation, smaller, and relatively flatter in curvature. Morlocks have a monocular field of view of about 3.13 steradians or 50% of a hemisphere. The coverage averages 115 deg along the vertical axis and 168 deg along the horizontal axis of the eye, with maximum resolution in the anteroventral quadrant. Adult male and female eloi of comparable size have eyes which are relatively more round, often lighter in pigmentation, larger with more ommatidia, and relatively more bulged. Eloi have a monocular field of view of approximately 3.83 steradians or 61% of a hemisphere that covers 145 deg vertically and 185 deg horizontally. Eloi have more uniform resolution than morlocks with best resolution in the posteroventral quadrant. All horseshoe crabs examined, whether morlocks or eloi, have an identical orientation of the margin of the eye relative to the animals' coordinates.     

Schlafen, a new family of growth regulatory genes that affect thymocyte development

The Schlafen (Slfn) family of genes are differentially regulated during thymocyte maturation and are preferentially expressed in the lymphoid tissues. Ectopic expression of the prototype member Slfn1 early in the T lineage profoundly alters cell growth and development. In these mice, the DP thymocytes fail to complete maturation, and, depending on the transgene dosage, the number of thymocytes is reduced to 1%-30% of normal. Furthermore, expression of the Schlafen family members in fibroblasts and thymoma cells either retards or ablates cell growth. The conceptual protein sequences deduced for each of the family members have no similarity to characterized proteins and must therefore participate in a heretofore unknown regulatory mechanism guiding both cell growth and T cell development.     

Presence of atrial natriuretic peptide in two desert rodents: comparison with rat

Atrial natriuretic peptide (ANP) was characterized and assayed in plasmas, hearts, and brains of two Algerian desert rodents, Psammomys obesus and Meriones libycus along with vasopressin, which was assayed in hypophyses and hypothalami. Using reverse-phase high-performance liquid chromatography and radioimmunoassay, we showed, in plasmas and hearts of both species of desert rats, the presence of peptides similar to rat N- and C-terminal ANP but in lower amounts than in Wistar rats. Conversely, C-terminal ANP was abundantly detected in hypophyses from Meriones libycus rats. As these peptides, through their diuretic and natriuretic activities, are involved in body fluid regulation and electrolyte balance, the reduction of ANP stores in both plasmas and hearts suggests that diuresis and natriuresis are lowered in both species of mammals adapted to arid environments. This could occur because of the vasopressin-mediated adaptation, but also in response to the low ANP involvement in hydro-osmotic regulations, even in Psammomys, which has a dietary salt loading. On the other hand, the higher C-terminal ANP contents in the hypophysis of Meriones than in Psammomys and Wistar rats remain to be understood.     

软熔带形状参数对高炉下部压力场的影响

利用商业软件fluent研究了不同的软熔带形状参数下高炉下部压力场的变化。分析得出以下结论:倒V形软熔带有利于降低高炉下部压力,高炉下部中心轴和炉墙处的压力随着软熔带厚度、宽度和根高的减少而降低,软熔带形状和根高的改变所带来的效果不如改变软熔带宽度和矿焦层厚度比所带来的效果明显。     

From genes to individuals: developmental genes and the generation of the phenotype

The success of the genetic approach to developmental biology has provided us with a suite of genes that are involved in the regulation of ontogenetic pathways. It is therefore time to ask whether and how such genes might be involved in the generation of adaptive phenotypes. Unfortunately, the current results do not provide a clear answer. Most of the genes that have been studied by developmental biologists affect early embryonic traits with significant effects on the whole organism. These genes are often highly conserved which allows us to do comparative studies even across phyla. However, whether the same genes are also involved in short-term ecological adaptations remains unclear. The suggestion that early acting ontogenetic genes may also affect late phenotypes comes from the genetic analysis of quantitative traits like bristle numbers in Drosophila. A rough mapping of the major loci affecting these traits shows that these loci might correspond to well known early acting genes. On the other hand, there are also many minor effect loci that are as yet uncharacterized. We suggest that these minor loci might correspond to a different class of genes. In comparative studies of randomly drawn cDNAs from Drosophila we find that there is a large group of genes that evolve fast and that are significantly under-represented in normal genetic screens. We speculate that these genes might provide a large, as yet poorly understood, reservoir of genes that might be involved in the evolution of quantitative traits and short-term adaptations.     

Mhc-E polymorphism in Pongidae primates: the same allele is found in two different species

The results of 93 de la Caffinière thumb joint replacements in 71 patients were reviewed between 6 and 16 years. The survival rate was 89% at 16 years. Eleven thumb joints had failed requiring revision. The commonest reason for failure was aseptic loosening of the trapezial component. The failure rate was higher in men of working age than any other group, which possibly reflects the increased demands on the prosthesis of these patients. We support the use of this implant for degenerative osteoarthritis, but caution against its use in men under 65 years.     

Effect of ascorbic acid deficiency on mouse second molar tooth germs cultivated in vitro

Mandibular second molar tooth germs from two-day old mice were cultured in vitro, on millipore membranes, for periods of up to 20 days in liquid medium with or without added ascorbic acid. Tooth germs grown in ascorbate medium were characterized by relatively normal growth, differentiation, morphology and histology. Cuspation patterns were maintained. The epithelial root sheath continued to grow along the millipore membrane. Tooth germs cultured in ascorbate-deficient medium manifested a consistent and striking failure in maintenance of differentiated odontoblastic and ameloblastic tissue with arrest of predentin synthesis, severe structural collapse and reduction in size. Cuspation patterns were lost in scorbutic molars, with sinking of surface layers into pulpal tissue and flattening of the entire organ. This resulted in a lack of recognizable morphology and in severe disorganization of tissues. Only growing areas of the root sheath with associated proliferation of preameloblasts and pre-odontoblasts and adjacent pulpal tissue remained normal and refractory to ascorbate deficiency. Odontoblastic as well as ameloblastic layers were disrupted and cells were dedifferentiated. Newly differentiated odontoblasts became highly vacuolated when they became polarized and started to secrete extracellular matrix.     

Cross-interactions between two members of the Dlx family of homeobox-containing genes during zebrafish development

BACKGROUND: Calmodulin (CaM) is the major calcium-dependent regulator of a large variety of important intracellular processes in eukaryotes. The structure of CaM consists of two globular calcium-binding domains joined by a central 28-residue alpha helix. This linker helix has been hypothesized to act as a flexible tether and is crucial for the binding and activation of numerous target proteins. Although the way in which alterations of the central helix modulate the molecular recognition mechanism is not known exactly, the relative orientation of the globular domains seems to be of great importance. The structural analysis of central helix mutants may contribute to a better understanding of how changes in the conformation of CaM effect its function. RESULTS: We have determined the crystal structure of a calcium-saturated mutant of chicken CaM (mut-2) that lacks two residues in the central helix, Thr79 and Asp80, at 1.8 A resolution. The mutated shorter central helix is straight, relative to that of the wild-type structure. The loss of a partial turn of the central alpha helix causes the C-terminal domain to rotate 220 degrees around the helix axis, with respect to the N-terminal domain. This rotation places the two domains on the same side of the central helix, in a cis orientation, rather than in the trans orientation found in wild-type structures. CONCLUSIONS: The deletion of two residues in the central helix of CaM does not distort or cause a bending of the linker alpha helix. The main consequence of the mutation is a change in the relative orientation of the two globular calcium-binding domains, causing the hydrophobic patches in these domains to be closer and much less accessible to interact with the target enzymes. This may explain why this mutant of CaM shows a marked decrease in its ability to activate some enzymes while the mutation has little or no effect on its ability to activate others.     

A protective epitope of Moraxella catarrhalis is encoded by two different genes

The high-molecular-weight UspA protein of Moraxella catarrhalis has been described as being both present on the surface of all M. catarrhalis disease isolates examined to date and a target for a monoclonal antibody (MAb 17C7) which enhanced pulmonary clearance of this organism in a mouse model system (M. E. Helminen et al., J. Infect. Dis. 170:867-872, 1994). A recombinant bacteriophage that formed plaques which bound MAb 17C7 was shown to contain a M. catarrhalis gene, designated uspA1, that encoded a protein with a calculated molecular weight of 88,271. Characterization of an isogenic uspA1 mutant revealed that elimination of expression of UspA1 did not eliminate the reactivity of M. catarrhalis with MAb 17C7. In addition, N-terminal amino acid analysis of internal peptides derived from native UspA protein and Southern blot analysis of M. catarrhalis chromosomal DNA suggested the existence of a second UspA-like protein. A combination of epitope mapping and ligation-based PCR methods identified a second M. catarrhalis gene, designated uspA2, which also encoded the MAb 17C7-reactive epitope. The UspA2 protein had a calculated molecular weight of 62,483. Both the isogenic uspA1 mutant and an isogenic uspA2 mutant possessed the ability to express a very-high-molecular-weight antigen that bound MAb 17C7. Southern blot analysis indicated that disease isolates of M. catarrhalis likely possess both uspA1 and uspA2 genes. Both UspA1 and UspA2 most closely resembled adhesins produced by other bacterial pathogens.     

两种材料修复牙体楔状缺损疗效分析

叙述了光固化复合树脂与Dyract复合材料修复楔状缺损牙的疗效 ,提出了使用Dyract复合材料修复牙体楔状缺损优于光固化复合树脂     

From genes to development: phenogenetic contributions to developmental biology in Soviet Russia from 1917 to 1967

A prospective study of all new cases of chronic renal failure (CRF) including inservice referrals was done at our hospital over a period of 1 year from May 1994 to April 1995. The diagnosis of CRF was based on clinical, laboratory, and radiological features. Kidney biopsies were done when indicated. The patients were subdivided into various etiologic groups of primary renal disease according to standard criteria. There were a total of 835 cases of CRF with a median age of 43 years (range 10 days to 90 years); 67.8% of them were men. Glomerulonephritis (28.6%), diabetic nephropathy (23.2%), and interstitial nephritis (16.5%) were the most common causes of CRF, followed by obstructive nephropathy (6.4%), benign nephrosclerosis (4.1%), and polycystic kidney disease (2%). However, in patients more than 40 years of age, diabetic nephropathy was the most common cause (36.8%). The cause of CRF was unknown in 16.2% of the cases. One hundred twenty-one patients (14.5%) had an acute deterioration of their underlying renal dysfunction at presentation. This was most commonly due to accelerated hypertension (26.1%), infection (22.4%), volume depletion (20.1%), and drugs (14.9%). Anti-inflammatory drugs were the most common drugs responsible for the acute decline in renal function. One year after their initial presentation, of the 512 patients (61.3%) with end stage renal disease, 12.5% had died, 17% had received a kidney allograft, 12.7% were on some form of maintenance dialysis, and 295 patients were lost to follow-up. Of the 323 patients with less severe illness, 7 died, 209 were on outpatient treatment, and 107 patients were lost to follow-up. We conclude that the pattern of CRF in India does not differ greatly from that in the developed countries. However, it carries a poorer prognosis due to late referral and limited availability and affordability of renal replacement therapy in India.     

Inhibition of the development of Plasmodium yoelii in exoerythrocytic stage in rodents (rats) with Chrysanthemum morifolium

Salt iodination, in Lebanon, started partially in late 1992, and was implemented in a uniform manner by January 1995. Following salt iodination, an epidemic of iodine-induced thyrotoxicosis occurred, as noted by the author, in his private clinic. The number of thyrotoxic patients increased sharply by 2 to 6 folds, and the yearly incidence rose from a baseline of 0.02% up to 0.07%. The younger patients have predominantly Graves' disease (32% of the cases), while 17% have solitary thyroid nodules, and 44% of the cases were elderly subjects with multinodular goiter. The pathogenesis and possible causes of this epidemic are discussed.     

Association of herpesvirus infection with the development of genital cancer

Clinical observations and epidemiological studies on genital cancer have revealed an association with sexual behavior, thus motivating research into sexually transmitted agents which may be responsible for the neoplasia. In this study, we used the PCR technique to examine the presence of CMV, HSV and EBV viruses in 187 cases of human genital lesions and found that infection with CMV or HSV was associated with cervical cancer. When we stratified according to HPV status this association was found only for HPV-DNA-negative cases. These findings indicate that past infection with CMV or HSV could be interpreted as a surrogate marker of HPV infection. However, these viruses may play an important role themselves in cervical cancer.