Molecular evidence for Triticum speltoides as a B-genome progenitor of wheat (Triticum aestivum).

In polyploid wheat, the origin of the B-genome donor has remained relatively unknown in spite of a number of investigations attempting to identify the parental species. A project was designed to isolate and clone a genome-specific DNA sequence from Triticum speltoides L. to determine if that species could be the B-genome donor. A cloning scheme involving the prescreening of 1-kb fragments followed by colony, dot blot, and Southern blot hybridization screenings was used to isolate a speltoides-specific sequence (pSp89.XI). The methods used allowed for rapid isolation of a genome-specific sequence when screened against total DNA from closely related species. Subsequent analyses showed that the sequence was barely detected in any of the other genomes of the annual Sitopsis section. The results of dot blot and Southern blot analyses established that (i) the sequence pSP89.XI, specific to T. speltoides relative to the other species of the Sitopsis section, was present in the genomes of tetraploid and hexaploid wheat, (ii) the relative abundance of pSp89.XI seemed to decrease from the diploid to the polyploid wheats, and (iii) the existence of a related, but modified B genome in polyploid wheat compared with that in modern T. speltoides was probable. Key words : genome-specific, DNA.     

ANTIVIRAL ACTIVITY OF CULTURED BLUE-GREEN ALGAE (CYANOPHYTA)1

Lipophilic and hydrophilic extracts from approximately 600 strains of cultured cyanophytes, representing some 300 species, were examined for antiviral activity against three pathogenic viruses. Approximately 10% of the cultures produced substances that caused significant reduction in cytopathic effect normally associated with viral infection. The screening program identified the order Chroococcales as commonly producing antiviral agents.     

Combining parametric and nonparametric models to estimate treatment effects in observational studies

Performing causal inference in observational studies requires we assume confounding variables are correctly adjusted for. In settings with few discrete-valued confounders, standard models can be employed. However, as the number of confounders increases these models become less feasible as there are fewer observations available for each unique combination of confounding variables. In this paper, we propose a new model for estimating treatment effects in observational studies that incorporates both parametric and nonparametric outcome models. By conceptually splitting the data, we can combine these models while maintaining a conjugate framework, allowing us to avoid the use of Markov chain Monte Carlo (MCMC) methods. Approximations using the central limit theorem and random sampling allow our method to be scaled to high-dimensional confounders. Through simulation studies we show our method can be competitive with benchmark models while maintaining efficient computation, and illustrate the method on a large epidemiological health survey.     

Seasonal variations in pituitary LH-gonadotropes of the hibernating bat Myotis lucifugus lucifugus: an immunohistochemical study

Pituitary gonadotropes were identified throughout the year in the seasonally breeding, hibernating bat Myotis lucifugus lucifugus by means of light microscopic immunohistochemistry. In both male and female bats, these cells were immunoreactive with an antiserum directed to the beta subunit of luteinizing hormone. Some gonadotropes were aggregated near a portion of the infundibular stalk which crosses the anterior lobe, while most were scattered singly in a uniform manner throughout the rest of the pars distalis. This cell population exhibited seasonal variations in both sexes. In males, the proportional volume of the pars distalis occupied by immunoreactive gonadotropes (volume fraction) was significantly reduced in late July, when plasma testosterone levels were approaching their seasonal peak. In females, the volume fraction declined in April, following ovulation, and remained low during pregnancy and lactation. The size and shape of gonadotropes appeared relatively constant throughout the annual reproductive cycle in male bats; the immunoreactive cells were irregular in shape, with cytoplasmic extensions insinuating between and often "cupping" other secretory cell types. In females, the gonadotropes resembled those of males throughout most of the year, except during pregnancy, when these cells became enlarged and ovoid. No evidence of involution was observed in these anterior pituitary cells in either males or females during hibernation.     

Variation in nuclear DNA in the genus Secale

Estimates of the 4C DNA amount per nucleus in 16 taxa of the genus Secale made by Feulgen microdensitometry ranged from 28.85 picograms (pg) in S. silvestre PBI R52 to 34.58 pg in S. vavilovii UM 2D49, compared with 33.14 pg in S. cereale cv. Petkus Spring which was used as a standard. Giemsa C-banding patterns showed considerable interspecific and intraspecific variation and several instances of polymorphism for large telomeric C-bands. The proportion of telomeric heterochromatin in the genome ranged from about 6% in S. silvestre and S. africanum to about 12% in cultivated rye. A detailed comparison of nine taxa showed no overall relationship between 4C DNA amount and the proportion of telomeric heterochromatin in the genome. However, evidence is presented which strongly supports the notion that the major evolutionary change in chromosome structure in Secale has involved the addition of heterochromatin at, or close to, the telomeres. It is suggested that saltatory amplification events at telomeres were initially responsible for each large increase in DNA amount. Subsequently unequal crossing over between homologues may have played an important secondary role by extending the range of variation in the amount of heterochromatin at a given telomere, while crossing over between non-homologues may have provided a useful mechanism allowing an increase in the DNA amount at one telomere to be distributed between chromosomes.     

Enzyme activities in human endometrium, myometrium and leiomyomas of the uterus.

Certain selected enzymes of carbohydrate metabolism were measured in samples of endometrium and myometrium from women who were premenopausal or postmenopausal. In addition, a number of samples of leiomyoma were obtained and assayed. Activities of several enzymes were higher in endometrium from premenopausal women compared to those in postmenopausal women; activities in myometrium were similar regardless of menopausal status. The activities of G6PD, ICD and GPI appeared to be lower in leiomyoma samples versus myometrial samples from premenopausal women; however, these differences were not apparent when enzyme activity was expressed per milligram protein.     

Hyaluronan-binding proteins on cultured J 774 macrophages.

Cultivated macrophages of murine cell-line J 774 were found to bind high-molecular-weight (molecular weight average approx. 5.10(6) [3H]hyaluronan (HA) by a saturable mechanism at 4 degrees C. Half-maximal binding was observed at 7-8 microgram/ml (1.4-1.6 nM) and the maximal binding was reached at 30-40 microgram/ml. Scatchard plot analysis revealed that approx. 20,000 molecules could bind to each cell with a Kd of 1.5 nM. The binding could be effectively inhibited by unlabeled HA. Also chondroitin sulphate inhibited the binding, but only to about 50%. At 37 degrees C the J 774 cells took up and degraded the polysaccharide effectively. Affinity chromatography on HA coupled to agarose of solubilized surface-iodinated J 774 cells, revealed that a protein of approx. 60 kDa, when analyzed by sodium dodecylsulfate polyacrylamide gel electrophoresis and autoradiography, could be specifically eluted with HA-oligosaccharides. Our results suggest that J 774 macrophages can bind HA by a mechanism compatible with receptor-binding, and carry a 60 kDa HA-binding protein on their surface. This receptor-binding may mediate uptake and degradation of the polysaccharide and influence the levels and turnover of HA in interstitial fluid as well as the release of HA into the bloodstream.     

Cloning and characterization of repetitive DNA sequences from genomes of Oryza minuta and Oryza australiensis

The value of genome-specific repetitive DNA sequences for use as molecular markers in studying genome differentiation was investigated. Five repetitive DNA sequences from wild species of rice were cloned. Four of the clones, pOm1, pOm4, pOmA536, and pOmPB10, were isolated from Oryza minuta accession 101141 (BBCC genomes), and one clone, pOa237, was isolated from Oryza australiensis accession 100882 (EE genome). Southern blot hybridization to different rice genomes showed strong hybridization of all five clones to O. minuta genomic DNA and no cross hybridization to genomic DNA from Oryza sativa (AA genome). The pOm1 and pOmA536 sequences showed cross hybridization only to all of the wild rice species containing the C genome. However, the pOm4, pOmPB10, and pOa237 sequences showed cross hybridization to O. australiensis genomic DNA in addition to showing hybridization to the O. minuta genomic DNA.     

The cysteine-rich domains of the insulin and insulin-like growth factor I receptors are primary determinants of hormone binding specificity. Evidence from receptor chimeras

To delineate the structural determinants of the insulin receptor (IR) and insulin-like growth factor I receptor (IGFIR) which affect hormone binding specificity we have constructed seven chimeric receptor cDNAs and stably expressed them in Chinese hamster ovary cells. Clonal cell lines expressing high levels of each receptor chimera were analyzed for insulin and insulin-like growth factor I (IGFI) binding activity. Measurements of hormone binding and immunoprecipitation of metabolically labeled receptors showed that all chimeras were properly processed and expressed at the cell surface. The binding data indicate that 56 amino acids of the IR and 52 amino acids of the IGFIR located in corresponding regions of the cysteine-rich domains are the primary determinants of hormone binding specificity. These regions are located between amino acids Asn-230 and Ile-285 on the IR and between His-223 and Met-274 on the IGFIR. In addition, the alpha IR-3 antibody, which competes for IGFI binding, was found to interact with the same 52 amino acids of the IGFIR which determines hormone specificity. Other antibodies which interfere with insulin binding (5D9, MC51, and MA20) interact with epitopes in the COOH-terminal 288 amino acids of the alpha-subunit. We conclude that 56 and 52 amino acids of the cysteine-rich domains of the IR and IGFIR contain the major determinants of hormone binding specificity although other more COOH-terminal regions of both receptors contribute to hormone binding.