Effects of spaceflight on rat humerus geometry, biomechanics, and biochemistry

The effects of a 12.5-day spaceflight (Cosmos 1887 biosatellite) on the geometric, biomechanical, and biochemical characteristics of humeri of male specific pathogen-free rats were examined. Humeri of age-matched basal control, synchronous control, and vivarium control rats were contrasted with the flight bones to examine the influence of growth and space environment on bone development. Lack of humerus longitudinal growth occurred during the 12.5 days in spaceflight. In addition, the normal mid-diaphysial periosteal appositional growth was affected; compared with their controls, the spaceflight humeri had less cortical cross-sectional area, smaller periosteal circumferences, smaller anterior-posterior periosteal diameters, and smaller second moments of area with respect to the bending and nonbending axes. The flexural rigidity of the flight humeri was comparable to that of the younger basal control rats and significantly less than that of the synchronous and vivarium controls; the elastic moduli of all four groups, nonetheless, were not significantly different. Generally, the matrix biochemistry of the mid-diaphysial cross sections showed no differences among groups. Thus, the spaceflight differences in humeral mechanical strength and flexural rigidity were probably a result of the differences in humeral geometry rather than material properties.     

人体小卫星DNA探针的制备

根据人体小卫星DNA核心顺序,化学合成长23碱基寡核苷酸探针,筛选人体基因组文库,旨在获得能用作遗传分析探针的小卫星顺序。结果得到15个含小卫星的阳性重组子。随机取其一(C_(35.9))作探针,试做群体分析。所有个体均可检出多条杂交带。其中某些带具有多态性。在一定检测条件下,检出的DNA图谱在有限的个体内具有个体特异性。结果表明筛选文库得到的小卫星顺序可用于小卫星多态性的检测。其它小卫星探针的筛选和应用性研究正在进行。     

A cytogenetic study of mentally retarded school children in taiwan with special reference to the fragile X chromosome

Summary A cytogenetic study was made on 341 mentally retarded children in the Provincial Nantou Rehabilitation Center for the Mentally Retarded and the St. Raphael Opportunity Center in Tainan. Of the 89 mentally retarded children with chromosomal abnormalities, 63 had Down syndrome, 13 had the fragile X [fra(X)] syndrome, and the remaining had other aneuploid constitutions. Family studies were possible for 2 of the 13 fra(X) probands. The results of this study illustrate the contribution of chromosomal abnormalities to the pathogenesis of mental retardation in children.     

New segment synthesis of alpha-inhibin-92 by the acyl disulfide method

The thiocarboxyl group reacts with diaryl disulfides to give an unsymmetrical acyl disulfide in dimethylformamide (DMF) and a symmetrical diacyl disulfide in aqueous DMF. Both acyl disulfides react with the alpha-amino group to form the peptide bond. The method was used in a new segment synthesis of alpha-inhibin-92 (alpha-IB-92) with use of 2,2'-dipyridyl disulfide as activator. Thiocarboxyl peptides were synthesized by the solid-phase method on 4-[alpha-(Boc-Gly-S)benzyl]phenoxyacetamidomethyl-resin. The segments alpha-IB-92-(1-34)SH (I), Msc-alpha-IB-92-(35-65)SH (II), Msc-alpha-IB-92(66-92)OH (III), and Msc-alpha-IB-92-(35-92)OH (VI) were prepared in yields of 33, 36, 41, and 25%, respectively, with use of crystalline symmetrical anhydrides in double and triple coupling protocols. Segments I, II, and III were used in a 3-segment synthesis of alpha-IB-92 with an overall yield based on starting resin of about 8% while a 2-segment synthesis using I and IV gave 11%. An all stepwise synthesis of alpha-IB-92 gave 4.5%.     

A detailed analysis of early events during in-vitro fertilization of bovine follicular oocytes

Bovine follicular oocytes collected at slaughter were matured and fertilized in vitro with in-vitro capacitated spermatozoa. Analysis of 621 penetrated ova fixed at various times after in-vitro insemination led to definition of 6 stages of early development. A time sequence for sperm penetration, sperm head decondensation, male pronucleus formation, the activation of second meiotic division, female chromosome decondensation and pronucleus development was established. First sperm penetration into the ooplasm was recorded 6 h after insemination; 1-2 h was required for the sperm head to decondense and another 4-6 h to develop into the opposing pronucleus stage. Synkaryosis and first cleavage occurred 28 h after fertilization. Examination of the early stages revealed four types of abnormalities, i.e. polyspermy, polygyny, asynchrony between male and female pronucleus development, and preactivation of cytokinesis.     

Molecular genotypes of the human T cell receptor gamma-chain

New RFLP of the human TCR gamma-chain defined by a single restriction enzyme (PvuII) are described. They define three alleles and allow haplotype assignments within families. They occur at a high frequency within the population studied and are useful for studies on disease associations with the gamma-chain genes. The PvuII sites flank the C gamma 2 gene. A polymorphic site maps to an area 0.5 kb downstream of C gamma 2-exon III. The second RFLP appears to be the result of a 3-kb insertion giving rise to differences in the number of copies of exon II in the C gamma 2 gene.     

Pyrimidine.pyrimidine base-pair mismatches in DNA. A nuclear magnetic resonance study of T.T pairing at neutral pH and C.C pairing at acidic pH in dodecanucleotide duplexes

Structural features of pyrimidine.pyrimidine mismatches in the interior of oligonucleotide duplexes have been investigated by high resolution two-dimensional proton nuclear magnetic resonance (n.m.r.) spectroscopy. These studies were conducted on the self-complementary d(C-G-C-T-A-G-C-T-T-G-C-G) duplex (designated T.T 12-mer) and the self-complementary d(C-G-C-C-A-G-C-T-C-G-C-G) duplex (designated C.C 12-mer) containing T.T and C.C pairs located at identical positions four base-pairs from either end of the duplex. Proton n.m.r. studies on the T.T 12-mer duplex were undertaken in the neutral pH range, while studies on the C.C 12-mer duplex were recorded at acidic pH. The proton spectra narrowed considerably on lowering the pH below neutrality for the C.C 12-mer duplex. Two-dimensional nuclear Overhauser enhancement spectroscopy (NOESY) data sets have been recorded on the T.T 12-mer and C.C 12-mer duplexes in high salt H2O and D2O solution. The magnitude of the NOE crosspeaks and the directionality of the NOE connectivities demonstrate that both duplexes are right-handed with all bases, including those at the mismatch site, adopting an anti configuration about the glycosidic bond. The observed base and sugar proton chemical shifts suggest structural similarities for the trinucleotide segments centered about the T.T and C.C mismatches. A NOE is detected between the resolved imino protons of T4 and T9 at the mismatch site, consistent with formation of a stacked "wobble" T4(anti).T9(anti) pair in the T.T 12-mer duplex. A comparison of the imino proton chemical shift and NOE data suggests that the imino-carbonyl hydrogen bonds in the wobble T.T mismatch are weaker than the corresponding imino-carbonyl hydrogen bonds in the wobble G.T mismatch. The 4-amino protons of C4 and C9 at the mismatch site in the C.C 12-mer duplex do not exhibit the pattern of hydrogen-bonded and exposed protons separated by approximately 1.5 parts per million characteristic of cytidine amino protons involved in Watson-Crick G.C pairing. The experimental data are insufficient to differentiate between wobble C(anti).C+(anti) and other pairing possibilities for the mismatch in the C.C 12-mer duplex at acidic pH.     

若干铁杉属植物核型的比较研究

本文首次报道了我国特产的重点保护植物南方铁杉的核型,全由中部和近中部着丝点染色体构成,核型公式为K(2n)=2x=24=20m+4sm,属“ 2A”类型。染色体的相对长度组成为2n=24=12M_2+10M_1+2S。通过比较。发现东亚的南方铁杉的核型与台湾铁杉甚为相似而略具进化的趋势,但北美东部的卡罗来纳铁杉的核型比它们进化得多。本文支持Florin认为铁杉属至少在早第三纪存在一条从欧亚大陆经过白令海峡到达北美洲的迁移路线的意见。