An unusual type of cilium.

The connective tissue cells of the dentinal pulp of unerupted dog teeth possess occasional cilia. Internally there are 4 to 8 peripheral doublets and one central doublet. Nine peripheral doublets are observed only close to or near the basal body.     

Uncoating of adenovirus type 2.

The uncoating of adenovirus type 2 and a temperature-sensitive mutant, tsl, was studied. HEp-2 cells were infected with 32P- OR 125I-labeled purified virions for various lengths of time, and the nuclear and cytoplasmic fractions were analyzed by sucrose gradient velocity sedimentation and sodium dodecyl sulfate-polyacryl-amide gel electrophoresis. Within 1 h of infection, virions were converted into three subviral structures: (1) subviral structures in the cytoplasm with a density greater than virions but which qualitatively still contained all virus polypeptides; (ii) corelike structures associated with both the nuclear and cytoplasmic fractions and composed of viral DNA and polypeptides VIa2, V and PVII; and (iii) putative DNA-terminal protein complexes in the nuclei. The kinetic and compartmentalization studies suggested that the DNA-terminal protein complex is the end product of uncoating. The virions which were synthesized by tsl at the nonpermissive temperature and contained the precursor polypeptides PVI and PVII were found to be blocked in uncoating at the corelike stage. This block in uncoating provides the explanation for the lack of infectivity of these virions. A model for the uncoating of adenovirus is proposed.     

小麦温型现象研究

通过多年来用红外技术对不同品种小麦群体温度进行连续观测,结果发现,小麦具有温型现象.不同温度型的小麦在外部和内部性状上各有一些鲜明特点.冷型小麦的许多重要性状较暖型小麦为优.功能叶的功能期长10.8%,每株根数多20条,旗叶的叶绿素含量、蒸腾率和净光合率分别高出0.1389g·100g^-1·FW、0.0035mol·m^-2·s^-1和4.71μmol·m^-2·s^-1.由此可以认为,温度型和小麦的一系列重要性状密切相关.     

Human papillomavirus type 48.

The cloning and partial characterization of the genome of human papillomavirus (HPV) type 48 is presented. Hybridization and short DNA sequence analyses permitted the alignment of the genome to the HPV genetic map.     

Physical maps of bovine papillomavirus type 1 and type 2 genomes.

Physical maps of bovine papillomavirus type 1 and type 2 (BPV-1 and BPV-2) DNA were constructed from analysis of the electrophoretic mobilities of restriction endonuclease cleavage fragments from dual digests. BPV-1 DNA was sensitive to Hind III, HindIII, EcoRI, HpaI, AND BamHI, with all but HindII yielding single scissions. BPV-2 DNA was resistant to EcoRI, and HindIII had one cleavage site whereas HpaI, BamHI, and HindII yielded multiple fragments. Of four BPV-1 isolates examined, DNA from one isolate was resistant to HindIII, and another DNA isolate was resistant to BamHI. The three BPV-2 isolates examined were uniformly sensitive to the restriction endonucleases employed.     

Protease of adenovirus type 2. Subcellular localization.

The subcellular localization of the adenovirus type 2 core polypeptide specific protease activity was investigated using an in vitro assay system. The protease activity was recovered exclusively from infected cell nuclei and was insoluble, sedimenting with the membrane fraction. Endogenous activity could be demonstrated in young virions which contain precursor PVII molecules. This protease activity only became sensitive to L-1-tosylamide-2-phenylethylchloromethyl ketone- or phenylmethylsulfonyl fluoride-mediated inhibition after disruption of the virus particles by sonication, suggesting that the enzyme was internally located. The putative precursors to virus particles, referred to as top components, which do not contain a full complement of viral DNA, did not contain protease activity. The protease released from sonicated virions converted exogenous PVII substrate molecules to polypeptide VII. The noninfectious H2ts1 virus particles synthesized at the nonpermissive temperature phenotypically resemble young virions, but unlike their wild type counterparts, were devoid of protease activity. The results show that the protease enters the precursor particles concurrently with the viral chromosome and that its presence is a prerequisite for the processing and subsequent maturation of infectious adenovirions.     

Human papillomavirus type 53.

The cloning and partial characterization of the genome of human papillomavirus type 53 is presented. The virus is a distinct type and is most closely related to human papillomavirus type 30.     

The type I and type II 11beta-hydroxysteroid dehydrogenase enzymes.

Local tissue concentrations of glucocorticoids are modulated by the enzyme 11β-hydroxysteroid dehydrogenase which interconverts cortisol and the inactive glucocorticoid cortisone in man, and corticosterone and 11-dehydrocorticosterone in rodents. The type I isoform (11β-HSD1) is a bidirectional enzyme but acts predominantly as a oxidoreductase to form the active glucocorticoids cortisol or corticosterone, while the type II enzyme (11β-HSD2) acts unidirectionally producing inactive 11-keto metabolites. There are no known clinical conditions associated with 11β-HSD1 deficiency, but gene deletion experiments in the mouse indicate that this enzyme is important both for the maintenance of normal serum glucocorticoid levels, and in the activation of key hepatic gluconeogenic enzymes. Other important sites of action include omental fat, the ovary, brain and vasculature. Congenital defects in the 11β-HSD2 enzyme have been shown to account for the syndrome of apparent mineralocorticoid excess (AME), a low renin severe form of hypertension resulting from the overstimulation of the non-selective mineralocorticoid receptor by cortisol in the distal tubule of the kidney. Inactivation of the 11β-HSD2 gene in mice results in a phenotype with similar features to AME. In addition, these mice show high neonatal mortality associated with marked colonic distention, and remarkable hypertrophy and hyperplasia of the distal tubule epithelia. 11β-HSD2 also plays an important role in decreasing the exposure of the fetus to the high levels of maternal glucocorticoids. Recent work suggests a role for 11β-HSD2 in non-mineralocorticoid target tissues where it would modulate glucocorticoid access to the glucocorticoid receptor, in invasive breast cancer and as a mechanism providing ligand for the putative 11-dehydrocorticosterone receptor. While previous homologies between members of the SCAD superfamily have been of the order of 20–30% phylogenetic analysis of a new branch of retinol dehydrogenases indicates identities of >60% and overlapping substrate specificities. The availability of crystal structures of family members has allowed the mapping of conserved 11β-HSD domains A–D to a cleft in the protein structure (cofactor binding domain), two parallel β-sheets, and an -helix (active site), respectively.     

Human skin collagen. Presence of type I and type III at all levels of the dermis.

Human skin was sliced with a dermatome, and the ratio of type I to type III collagens at various depths was assayed by comparing the quantities of peptides of each derived from cyanogen bromide digestion of the cut skin. Although immunofluorescent studies have suggested type III collagen is located predominantly beneath the epidermis and around appendages, biochemical determination demonstrates the same ratio of type I to type III collagen at all levels of the dermis even in the absence of cutaneous appendages.     

Lipoproteins of Haemophilus influenzae type b.

Haemophilus influenzae type b Minn A produced 12 lipoproteins with apparent molecular weights of between 14,000 and 67,000. The lipoproteins were identified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and fluorography of delipidated extracts of cells grown in [3H]palmitate. When the delipidated cell extracts were subjected to acid methanolysis, tritium was quantitatively recovered as palmitate and methyl palmitate, indicating that the [3H]palmitate had not been degraded and reincorporated into nonlipid material during cell growth. One of the lipoproteins comigrated with outer membrane protein (OMP) P6. OMP P6 was purified from [3H]palmitate-labeled cells. The purified protein preparation contained both amide- and ester-linked fatty acids. We conclude that (i) H. influenzae type b produces several lipoproteins, and (ii) one of these lipoproteins is OMP P6, a protein under consideration as a vaccine component.     

Isolation of type I and type II GABAA-benzodiazepine receptors by immunoaffinity chromatography.

Anti-peptide alpha 1 (1-9) and anti-peptide alpha 3 (459-467) antibodies coupled to Affigel-10 were used for the isolation of GABAA receptors containing the alpha 1- or alpha 3-subunit, respectively. Both types of GABAA receptors exhibited a high affinity for [3H]flunitrazepam, and binding of [3H]flunitrazepam was stimulated in the presence of GABA. GABAA receptors eluted from the anti-peptide alpha 1 (1-9) immunoaffinity column exhibited a high affinity and those from the anti-peptide alpha 3 (459-467) columns a low affinity for the type I benzodiazepine receptor-selective ligand Cl 218872, indicating the enrichment of type I and type II GABAA-benzodiazepine receptors, respectively.     

Three-dimensional structure of a mouse-adapted type 2/type 1 poliovirus chimera.

The crystal structure of V510, a chimeric type 2/type 1 poliovirus, has been determined at 2.6 A resolution. Unlike the parental Mahoney strain of type 1 poliovirus, V510 is able to replicate in the mouse central nervous system, due entirely to the replacement of six amino acids in the exposed BC loop of capsid protein VP1. Significant structural differences between the two strains cluster in a major antigenic site of the virus, located at the apex of the radial projection which surrounds the viral five-fold axis. Residues implicated in the mouse-virulence of poliovirus by genetic studies are located in this area, and include the residues which are responsible for stabilizing the conformation of the BC loop in V510. Despite evidence that this area is not involved in receptor binding in cultured primate cells, the genetic and structural observations suggest that this area plays a critical role in receptor interactions in the mouse central nervous system. These results provide a structural framework for further investigation of the molecular determinants of host and tissue tropism in viruses.