Maximum survival of frozen goat embryos is attained at the expanded, hatching and hatched blastocyst stages of development

Embryos were collected 5, 6 and 7 days after ovulation to determine their optimum stage of development for cryopreservation. The embryos were frozen using either glycerol or dimethyl sulfoxide (DMSO) as cryoprotectant, and then thawed and cultured to determine their viability. The rate of survival increased as the stage of development of the embryos increased. All hatched blastocysts survived freezing regardless of which cryoprotectant was used, whereas none of the 22 morulae frozen with DMSO survived, and only 12 of the 63 morulae frozen with glycerol survived. At the early blastocyst stage there was a significantly different result between freezing procedures (P less than 0.05) with greater survival rates obtained using DMSO rather than glycerol. The viability of goat embryos obtained at the early to hatched blastocyst stages, when collected 7 days after ovulation, was assessed by transferring half the embryos singly to recipients and freezing the remainder before transfer. When pregnancy was tested at the 7th week of gestation, the survival rate of fresh embryos was 67/111 (60%) compared with 64/109 (59%) for frozen-thawed embryos.

[Observation on the annual and seasonal changes of anatomic characteristics of the main root of Panax ginseng C.A. Meyer]

Annual dynamic of the main root of Panax ginseng shows that the cross-section of various tissues increases gradually with age, but the ratio of phloemxylem in cross-section decreases. Seasonal dynamic shows that cells of phellogen and cambium divide actively in June-July and gets retarded in August. Ecological conditions can influence annual and seasonal dynamics of the structure of the main root.

[Study of the relation of the typology of nephrotic syndrome and red cell C3b receptor, T cell function]

This paper reports the determined results of rosette rates of red cell C3b receptor and active rosette (Ea) rates of T lymphocyte in 39 cases of nephrotic syndrome. Typology of nephrotic syndrome according to TCM differentiation symptoms, all the 39 cases were divided into three types: (1) 13 cases of deficiency of Qi of the Spleen with stagnancy of dampness; (2) 9 cases of deficiency of Yang of the Spleen and Kidney; (3) 17 cases of deficiency of Yin of the Liver and Kidney. The results showed that the red cell C3b receptor rosette rate and Ea rosette rate in 39 cases of nephrotic syndrome were significantly lower than those in the control. The difference between the two groups was very obvious (P less than 0.001) among the three types. The rosette rates of both in the deficiency of Qi of the Spleen and deficiency of Yang of the Spleen and Kidney were markedly decreased than those in the control (P less than 0.001). Whereas, the red cell C3b receptor rosette rate was lower than that in the control (P less than 0.01), and T cell Ea rosette rate showed no statistical difference (P greater than 0.05) in the deficiency of Yin of the Liver and Kidney. There was a close relationship between the immune dysfunction of red cell and the pathogenesis in nephrotic syndrome. There was markedly relationship between the pathogenesis of deficiency of Yang of the Spleen and Kidney and deficiency of Qi of Spleen with stagnancy of dampness and T cell immune dysfunction. While the Ea level in deficiency of Yin of the Liver and Kidney was closely correlated with the control. Probably this type was nephrotic nephrosis which had been treated with TCM-WM.

Specific recognition nucleotides and their DNA context determine the affinity of E2 protein for 17 binding sites in the BPV-1 genome

The DNA context of nucleotides that a protein recognizes can influence the strength of the protein-DNA interaction. Moreover, in prokaryotes, understanding the quantitative differences in binding affinities that result in part from the DNA context is often important in describing regulatory mechanisms. Nevertheless, these issues have not been a major focus yet for the investigation of protein-DNA interactions in eukaryotes. In this study, we explored the binding specificity and the range of affinities that the BPV-1 E2 transcriptional activator has for DNA. Because E2 binding sites are positioned near several different BPV-1 promoters, such quantitative information may be important to understand transcriptional regulatory mechanisms in BPV-1. Gel retardation assays and DNA footprinting were used to quantitate the affinities of the E2 binding sites in the viral genome. In the process, five sites were discovered, which, on the basis of sequence, had not been predicted previously to interact with the E2 protein. Equilibrium and kinetic studies show that the range of E2 affinities of the 17 sites varied over 300-fold. The sequence elements responsible for E2 recognition of DNA were determined by missing contact analysis of several sites and a point mutation analysis of one site. The results presented show that the affinity of an E2 binding site is to a large extent determined by the availability of specific contacts, but the data also strongly suggest that DNA structure plays an important role.

Search for satellite reflections and low-temperature study of the 1223 and 2212 Tl–Ba–Ca–Cu–O superconductors

The structures of the 1223 and 2212 phases of the T1-Ba-Ca-Cu-O system have been determined at 125 K. No satellite reflections were observed in extensive searches at both room and low temperature. The temperature dependence of the thermal parameters of the thallium atoms confirms the presence of a static disorder beyond that already incorporated in the refinements.

Pre-mRNA splicing mutants of Schizosaccharomyces pombe

A collection of temperature sensitive (ts-) mutants was prepared by chemical mutagenesis of a wild type Schizosaccharomyces pombe strain. To screen the ts- mutants for pre-mRNA splicing defects, an oligodeoxynucleotide that recognizes one of the introns of the beta-tubulin pre-mRNA was used as a probe in a Northern blot assay to detect accumulation of intron sequences. This screening procedure identified three pre-mRNA splicing mutants from 100 ts- strains. The three mutants are defective in an early step of the pre-mRNA splicing reaction; none accumulate intermediates. The precursors that accumulate at 37 degrees C are polyadenylated. Analysis of the splicing of another pre-mRNA showed that the mutations are not specific for beta-tubulin. The total RNA pattern in the three splicing mutants appears to be normal. In addition, the amounts of the spliceosomal snRNAs are not drastically changed compared to the wild type and splicing of pre-tRNAs is not blocked. Genetic analyses demonstrate that all three splicing mutations are tightly linked to the ts- growth defects and are recessive. Crosses among the mutants place them in three complementation groups. The mutants have been named prp1, prp2 and prp3.

Expression of the three influenza virus polymerase proteins in a single cell allows growth complementation of viral mutants

Transformed cell lines derived from murine C127 cells were constructed that express the influenza virus RNA-dependent RNA polymerase proteins (PA, PB1, and PB2). Cell lines that express only one or all three of the proteins were tested for their ability to complement temperature-sensitive viral mutants incubated at the nonpermissive temperature. Two cell lines were isolated that express all three polymerase genes and complement the growth of PB2 temperature-sensitive mutants at the nonpermissive temperature. One of these lines also complemented PA temperature-sensitive mutants. The viral titers obtained in these two cell lines were 12-fold to 1000-fold higher than the viral titers obtained upon growth of the corresponding temperature-sensitive mutant in C127 cells at the nonpermissive temperature.

Comparison of the inhibition of Escherichia coli and Lactobacillus casei dihydrofolate reductase by 2,4-diamino-5-(substituted-benzyl)pyrimidines: quantitative structure-activity relationships, X-ray crystallography, and computer graphics in structure-activity analysis

The inhibition constants (Kiapp) obtained from the action of 44 2,4-diamino-5-(substituted-benzyl)pyrimidines on dihydrofolate reductase (DHFR) from Escherichia coli and Lactobacillus casei bacteria are used to derive quantitative structure-activity relationships (QSAR). These equations bring out a number of differences in the DHFR which can be understood at the atomic level by studying color stereo computer graphics models constructed from the X-ray coordinates of the enzyme-inhibitor complexes. The combination of QSAR and X-ray crystallography interpreted via high-performance computer graphics offers a new level of sophistication to extend our understanding of enzyme-ligand interactions, which, when the crystallography is known, opens up a more scientific approach to drug development.

Inhibition by 5-(substituted-benzyl)-2,4-diaminopyrimidines of murine tumor (L5178Y) cell cultures sensitive to and resistant to methotrexate. Further evidence for the sensitivity of resistant cells to hydrophobic drugs

Forty-three 5-(substituted-benzyl)-2,4-diaminopyrimidines have been studied as inhibitors of murine tumor cell cultures (L5178Y). Two types of cells were used--one resistant to methotrexate and one sensitive to methotrexate. The formulation of quantitative structure--activity relationships showed that the methotrexate-resistant cells are more sensitive to the more hydrophobic congeners. pi 0 for the sensitive cells is about 1.4, while pi 0 for the methotrexate-resistant cells is above 3. These results are similar to those found for 2,4-diaminotriazines (Selassie, C.D.; Guo, Z. R.; Hansch, C.; Khwaja, T. A.; Pentecost, S. J. Med. Chem. 1982, 25, 157).

A comparison of the inhibitory action of 5-(substituted-benzyl)-2,4-diaminopyrimidines on dihydrofolate reductase from chicken liver with that from bovine liver

Forty-four 5-(substituted-benzyl)-2,4-diaminopyrimidines have been tested as inhibitors of chicken and bovine liver dihydrofolate reductase. The chicken enzyme is, on the average, about 10 times less easily inhibited than bovine enzyme. Substituents which show the greatest selectivity are 4-NHCOCH3, 3-OC4H9, 3-I, 3-CF3-4-OCH3, and 3,4,5-(OCH3)3. The inhibition constants have been used to formulate quantitative structure-activity relationships for comparative purposes.