猕猴、食蟹猴群中STLV-1病毒感染状况研究初报

[目的]摸清STLV-1感染现状,从而有效地降低STLV-1在猕猴、食蟹猴群中的的感染率。[方法]采用STLV-1ELISA法对猕猴、食蟹猴血清进行抗体检测。结果本中心送美国BioReliance公司的2455只出口猴血清,103份血清呈STLV-1抗体阳性,19份血清呈STLV-1抗体可疑,其余血清均为STLV-1抗体阴性。[结论]猕猴、食蟹猴群中STLV-1的平均感染率为4.97%,其中猕猴STLV-1感染率为2.7%,食蟹猴STLV-1感染率为5.4%,是猕猴STLV-1感染率的2倍;随着年龄的增长,猕猴(食蟹猴)STLV-1的感染率也随之升高。     

Biosynthetic relationship among aflatoxins B1, B2, M1, and M2.

Aflatoxins are a family of toxic, acetate-derived decaketides that arise biosynthetically through polyhydroxyanthraquinone intermediates. Most studies have assumed that aflatoxin B1 is the biosynthetic precursor of the other aflatoxins. We used a strain of Aspergillus flavus which accumulates aflatoxin B2 to investigate the later stages of aflatoxin biosynthesis. This strain produced aflatoxins B2 and M2 but no detectable aflatoxin B1 when grown over 12 days in a low-salt, defined growth medium containing asparagine. Addition of dichlorvos to this growth medium inhibited aflatoxin production with concomitant accumulation of versiconal hemiacetal acetate. When mycelial pellets were grown for 24, 48, and 72 h in growth medium and then transferred to a replacement medium, only aflatoxin B2 and M2 were recovered after 96 h of incubation. Addition of sterigmatocystin to the replacement medium led to the recovery of higher levels of aflatoxins B2 and M2 than were detected in control cultures, as well as to the formation of aflatoxins B1 and M1 and O-methylsterigmatocystin. These results support the hypothesis that aflatoxins B1 and B2 can arise independently via a branched pathway.     

Fourier transform infrared double-flash experiments resolve bacteriorhodopsin''s M1 to M2 transition.

The orientation of the central proton-binding site, the protonated Schiff base, away from the proton release side to the proton uptake side is crucial for the directionality of the proton pump bacteriorhodopsin. It has been proposed that this movement, called the reprotonation switch, takes place in the M1 to M2 transition. To resolve the molecular events in this M1 to M2 transition, we performed double-flash experiments. In these experiments a first pulse initiates the photocycle and a second pulse selectively drives bR molecules in the M intermediate back into the BR ground state. For short delay times between initiating and resetting pulses, most of the M molecules being reset are in the M1 intermediate, and for longer delay times most of the reset M molecules are in the M2 intermediate. The BR-M1 and BR-M2 difference spectra are monitored with nanosecond step-scan Fourier transform infrared spectroscopy. Because the Schiff base reprotonation rate is kM1 = 0.8 x 10(7) s(-1) in the light-induced M1 back-reaction and kM2 = 0.36 x 10(7) s(-1) in the M2 back-reaction, the two different M intermediates represent two different proton accessibility configurations of the Schiff base. The results show only a minute movement of one or two peptide bonds in the M1 to M2 transition that changes the interaction of the Schiff base with Y185. This backbone movement is distinct from the larger one in the subsequent M to N transition. No evidence of a chromophore isomerization is seen in the M1 to M2 transition. Furthermore, the results show time-resolved reprotonation of the Schiff base from D85 in the M photo-back-reaction, instead of from D96, as in the conventional cycle.     

麂属(Muntiacus)动物MDR-1基因序列分析及其分子进化关系

对麂属（Muntiacus)中的3种动物：赤麂（M.muntjak)(2n-6♀,7♂）,小麂（M.reevesi)(2n=46),黑麂（M.crinifrons(2n=8♀,9♂）MDR－1基因（multidrug resistance,多药耐药基因）726bp左右的片段进行了序列分析并根据序列信息建立分子系统树,同时探讨了这3种动物的起源,分类地位及进化关系。     

M1 and M3 muscarinic antagonists inhibit human nasal glandular secretion in vitro.

Mucus glycoproteins (MGP) are high-molecular-weight glycoconjugates that are released from submucosal glands and epithelial goblet cells in the respiratory tract. Muscarinic receptors have an important role in the regulation of human nasal glandular secretion and mucus production, but it is not known which of the five muscarinic receptor subtypes are involved. The effect of nonselective and M1-, M2-, and M3-selective muscarinic antagonists on methacholine (MCh)-induced MGP secretion from human nasal mucosal explants was tested in vitro. MGP was assayed by enzyme-linked immunosorbent assay using a specific anti-MGP monoclonal antibody (7F10). MCh (100 microM) induced MGP secretion up to 127% compared with controls. MCh-induced MGP release was significantly inhibited by atropine (100 microM), the M, receptor antagonist pirenzepine (10-100 microM), and the M3 receptor antagonist 4-diphenylacetoxy-N-methylpiperidine methiodide (4-DAMP; 1-100 microM). 4-DAMP significantly inhibited MCh-induced MGP release at a lower concentration (1 microM) than pirenzepine (10 microM). The M2 receptor antagonists AF-DX 116 and gallamine (both at 100 microM) had no effect. No antagonist alone had a significant effect on MGP release. These results indicate that the M1 and M3 muscarinic receptor subtypes regulate MGP secretion from human nasal mucosa and suggest that the M3 receptor has the predominant effect.     

SEPERATION OF MALLOMONAS DUERRSCHMIDTIAE SP. NOV. FROM M. CRASSISQUAMA AND M. PSEUDOCORONATA: IMPLICATIONS FOR PALEOLIMNOLOGICAL RESEARCH1

A new species, Mallomonas duerrschmidtiae, with characteristics common to both Mallomonas crassisquama (Asmund) Fott and Mallomonas pseudocoronata Prescott, is described from acidic lakes low in specific conductance and total phosphorus concentration. Characteristics of scales, bristles and spines serve to separate the three taxa. The length and area of scales of M. duerrschmidtiae are significantly larger than those of M. crassisquama but smaller than those of M. pseudocoronata. Although the anterior submarginal ribs of scales of M. duerrschmidtiae may become extended to form short wings, the scales lack the large forward projecting anterior wings characteristic of scales of M. pseudocoronata. Features of the dome and junction between the arms of the V-rib and anterior submarginal ribs also serve to distinguish between the three species. Cells of M. duerrschmidtiae also possess long, smooth and thick spines on their posterior scales and lack helmet bristles. M. duerrschmidtiae has different maxima along pH, temperature, specific conductance, total phosphorus and seasonal gradients than either M. crassisquama or M. pseudocoronata. Discriminant analysis, based on nine morphological characters, was used to successfully classify body scales of the three species. The importance of M. duerrschmidtiae as a bioindicator in future lake monitoring and paleolimnological inference studies is discussed.     

Gel retardation analysis of E. coli M1 RNA-tRNA complexes.

We have analyzed complexes between tRNA and E. coli M1 RNA by electrophoresis in non-denaturing polyacrylamide gels. The RNA subunit of E. coli RNase P formed a specific complex with mature tRNA molecules. A derivative of the tRNA(Gly), endowed with the intron of yeast tRNA(ile) (60 nt), was employed to improve separation of complexed and unbound M1 RNA. Binding assays with tRNA(Gly) and intron-tRNA(Gly) as well as analysis of intron-tRNA/M1 RNA complexes on denaturing gels showed that one tRNA is bound per molecule of M1 RNA. A tRNA carrying a truncation as small as the 5'-nucleotide had a strongly reduced affinity to M1 RNA and was also a weak competitor in the cleavage reaction, suggesting that nucleotide +1 is a major determinant of tRNA recognition and that the thermodynamically stable tRNA-M1 RNA complex is relevant for enzyme function. Binding was shown to be dependent on the M1 RNA concentration in a cooperative fashion. Only a fraction of M1 RNAs (50-60%) readily formed a complex with intron-tRNA(Gly), indicating that distinct conformational subpopulations of M1 RNA may exist. Formation of the M1 RNA-tRNA(Gly), complex was very similar at 100 mM Mg++ and Ca++, corroborating earlier data that Ca++ is competent in promoting M1 RNA folding and tRNA binding. Determination of apparent equilibrium constants (app Kd) for tRNA(Gly) as a function of the Mg++ concentration supports an uptake of at least two additional Mg++ ions upon complex formation. At 20-30 mM Mg++, highest cleavage rates but strongly reduced complex formation were observed. This indicates that tight binding of the tRNA to the catalytic RNA at higher magnesium concentrations retards product release and therefore substrate turnover.     

Coding R.M.EcoR1-plasmids derived from R-factor]

Bacteriophages P1vir and Mu-1 have been used for transductional shortening of recombinant R factor coding for R.M.EcoR1 isolated by Yoshimori et al. P1 shortening made possible the isolation of transmissive isogenic plasmids coding R.M.EcoR1 and differing in antibiotic resistances, as well as isolation of plasmids differing only in R.M.EcoR1 genes. Mu-1 mediated shortening favoured the isolation of transmissive R plasmids having lost the resistance to chloramphenicol but having all other markers of recombinant R factor intact. The data are interpreted in support of Yoshimori et al. supposition concerning the existence of R.M.EcoR1 coding recombinant R factor of Escherichia coli.     

Three different M1 RNA-containing viruslike particle types in Saccharomyces cerevisiae: in vitro M1 double-stranded RNA synthesis.

Killer strains of Saccharomyces cerevisiae bear at least two different double-stranded RNAs (dsRNAs) encapsidated in 39-nm viruslike particles (VLPs) of which the major coat protein is coded by the larger RNA (L-A dsRNA). The smaller dsRNA (M1 or M2) encodes an extracellular protein toxin (K1 or K2 toxin). Based on their densities on CsCl gradients, L-A- and M1-containing particles can be separated. Using this method, we detected a new type of M1 dsRNA-containing VLP (M1-H VLP, for heavy) that has a higher density than those previously reported (M1-L VLP, for light). M1-H and M1-L VLPs are present together in the same strains and in all those we tested. M1-H, M1-L, and L-A VLPs all have the same types of proteins in the same approximate proportions, but whereas L-A VLPs and M1-L VLPs have one dsRNA molecule per particle, M1-H VLPs contain two M1 dsRNA molecules per particle. Their RNA polymerase produces mainly plus single strands that are all extruded in the case of M1-H particles but are partially retained inside the M1-L particles to be used later for dsRNA synthesis. We show that M1-H VLPs are formed in vitro from the M1-L VLPs. We also show that the peak of M1 dsRNA synthesis is in fractions lighter than M1-L VLPs, presumably those carrying only a single plus M1 strand. We suggest that VLPs carrying two M1 dsRNAs (each 1.8 kilobases) can exist because the particle is designed to carry one L-A dsRNA (4.5 kilobases).     

Alpha 1 antitrypsin M1: a new common genetically determined variant.

A new common variant (M1) of alpha 1 antitrypsin was detected by isoelectric focusing of serum in a pH gradient of 3.5-5.0 in polyacrylamide gels. The variant can be clearly distinguished from the common M type only when alpha 1 antitrypsin M is present in the same serum. It cannot be recognized on starch gel electrophoresis. The gene frequency in a population sample of United States whites was .09.