Culture of one- and two-cell bovine embryos to the blastocyst stage in the ovine oviduct

The ovine oviduct was evaluated as a culture system for early bovine embryos. One- to two-cell embryos were collected from superovulated heifers killed 36 or 48 h after the onset of estrus, embedded in agar cylinders, and transferred to oviducts ligated at the uterotubal junction. After 5 d (6.5 to 7.0 d after donor estrus), embryos were recovered and evaluated for development to the late morula or blastocyst stage. In Experiment 1, 86 embryos were cultured in 10 ewes in which the onset of estrus was synchronized with that of the donors. Fifty-eight embryos (68%) were recovered; of these, 31 (53%) had continued normal development. In Experiment 2, development in ovariectomized versus intact cyclic ewes was compared. Recovery from ovariectomized ewes (26/39, 67%) did not differ from intact cyclic ewes (26/35, 74%) and the proportion developing normally also did not differ (ovariectomized: 7/26, 27%; intact cyclic: 11/26, 42%). In Experiment 3, embryo development was compared in anestrous versus ovariectomized ewes. Recovery rate (anestrous: 22/43, 51%; ovariectomized: 20/51, 39%) and the proportion developing normally (anestrous: 8/22, 37%; ovariectomized: 9/20, 45%) did not differ between treatments. Developmental competence of oviduct-cultured embryos was tested by transfer to 16 synchronous heifers, of which eight (50%) became pregnant; five delivered calves. Results indicate that the ovine oviduct provides an adequate site for the culture of early bovine embryos.     

Reduced orthostatic tolerance following 4 h head-down tilt

The cardiovascular responses to a 10-min 1.22 rad (70 degrees) head-up tilt orthostatic tolerance test (OST) was observed in eight healthy men following each of a 5-min supine baseline (control), 4 h of 0.1 rad (6 degrees) head-down tilt (HDT), or 4 h 0.52 rad (30 degrees) head-up tilt (HUT). An important clinical observation was presyncopal symptoms in six of eight subjects following 4 h HDT, but in no subjects following 4 h HUT. Immediately prior to the OST, there were no differences in heart rate, stroke volume, cardiac output, mean arterial pressure and total peripheral resistance for HDT and HUT. However, stroke volume and cardiac output were greater for the control group. Mean arterial pressure for the control group was less than HDT but not HUT. Over the full 10-min period of OST, the mean arterial pressure was not different between groups. Heart rate increased to the same level for all three treatments. Stroke volume decreased across the full time period for control and HDT, but only at 3 and 9 min for HUT. There was a higher total peripheral resistance in the HDT group than control or HUT. The pre-ejection period to left ventricular ejection time ratio was less in HDT than for control or HUT groups. These data indicate a rapid adaptation of the cardiovascular system to 4 h HDT that appears to be inappropriate on reapplication of a head to foot gravity vector. We speculate that the cause of the impaired orthostatic tolerance is decreased tone in venous capacitance vessels so that venous return is inadequate.     

Acrosome reaction of bovine spermatozoa in vivo: sites and effects of stages of the estrous cycle

Thirty-two cows were inseminated near the uterotubal junction at various stages of the estrous cycle and slaughtered 16 h later to determine the effects of stage of the estrous cycle and tubal site of sperm recovery on the frequency of acrosome-reacted bull spermatozoa. Slaughter times were 46, 70, 144, or 168 h after each cow was injected with prostaglandin (PG) F 2 alpha or during the luteal phase of the estrous cycle. Sperm were recovered from the upper uterus and the isthmus and ampulla of the oviducts and stained for both viability and acrosome reaction. The highest frequency of acrosome-reacted sperm was found in the ampulla ipsilateral to a dominant follicle (largest follicle present) or recent ovulation and primarily at 70 h after PGF2 alpha (P less than 0.05). Also, fewer sperm were acrosome reacted prior to (46 h post-PGF2 alpha) and well after (168 h post-PGF2 alpha) estrus than during or immediately postestrus (70, 90, and 144 h post-PGF2 alpha; P less than 0.05). Except for two cows, one at 46 h and one at 70 h, all cows with more than 50% acrosome-reacted sperm in the ampulla had ovulated before slaughter. These data suggest that capacitated sperm become localized in the ampulla of the oviduct of the ovulatory side around the time of ovulation.     

Localization of sequences regulating ancestral and acquired sites of esterase6 activity in Drosophila melanogaster

We have broadly defined the DNA regions regulating esterase6 activity in several life stages and tissue types of D. melanogaster using P- element-mediated transformation of constructs that contain the esterase6 coding region and deletions or substitutions in 5' or 3' flanking DNA. Hemolymph is a conserved ancestral site of EST6 activity in Drosophila and the primary sequences regulating its activity lie between -171 and -25 bp relative to the translation initiation site: deletion of these sequences decrease activity approximately 20-fold. Hemolymph activity is also modulated by four other DNA regions, three of which lie 5' and one of which lies 3' of the coding region. Of these, two have positive and two have negative effects, each of approximately twofold. Esterase6 activity is present also in two male reproductive tract tissues; the ejaculatory bulb, which is another ancestral activity site, and the ejaculatory duct, which is a recently acquired site within the melanogaster species subgroup. Activities in these tissues are at least in part independently regulated: activity in the ejaculatory bulb is conferred by sequences between -273 and -172 bp (threefold decrease when deleted), while activity in the ejaculatory duct is conferred by more distal sequences between -844 and -614 bp (fourfold decrease when deleted). The reproductive tract activity is further modulated by two additional DNA regions, one in 5' DNA (-613 to -284 bp; threefold decrease when deleted) and the other in 3' DNA (+1860 to +2731 bp; threefold decrease when deleted) that probably overlaps the adjacent esteraseP gene. Collating these data with previous studies suggests that expression of EST6 in the ancestral sites is mainly regulated by conserved proximal sequences while more variable distal sequences regulate expression in the acquired ejaculatory duct site.      

Nucleotide variation at the hypervariable esterase 6 isozyme locus of Drosophila simulans

Esterase 6 (Est-6/EST6) is polymorphic in both Drosophila melanogaster and D. simulans for two common allozyme forms, as well as for several other less common variants. Parallel latitudinal clines in the frequencies of the common EST6-F and EST6-S allozymes in these species have previously been interpreted in terms of a shared amino acid polymorphism that distinguishes the two variants and is subject to selection. Here we compare the sequences of four D. simulans Est-6 isolates and show that overall estimates of nucleotide heterozygosity in both coding and 5' flanking regions are more than threefold higher than those obtained previously for this gene in D. melanogaster. Nevertheless, the ratio of replacement to exon silent-site polymorphism in D. simulans is less than the ratio of replacement to silent divergence between D. simulans and D. melanogaster, which could be the result of increased efficiency of selection against replacement polymorphisms in D. simulans or to divergent selection between the two species. We also find that the amino acid polymorphisms separating EST6- F and EST6-S in D. simulans are not the same as those that separate these allozymes in D. melanogaster, implying that the shared clines do not reflect shared molecular targets for selection. All comparisons within and between the two species reveal a remarkable paucity of variation in a stretch of nearly 400 bp immediately 5' of the gene, indicative of strong selective constraint to retain essential aspects of Est-6 promoter function.      

Strategies for structural proteomics of prokaryotes: Quantifying the advantages of studying orthologous proteins and of using both NMR and X-ray crystallography approaches

Only about half of non-membrane-bound proteins encoded by either bacterial or archaeal genomes are soluble when expressed in Escherichia coli (Yee et al., Proc Natl Acad Sci USA 2002;99:1825-1830; Christendat et al., Prog Biophys Mol Biol 200;73:339-345). This property limits genome-scale functional and structural proteomics studies, which depend on having a recombinant, soluble version of each protein. An emerging strategy to increase the probability of deriving a soluble derivative of a protein is to study different sequence homologues of the same protein, including representatives from thermophilic organisms, based on the assumption that the stability of these proteins will facilitate structural analysis. To estimate the relative merits of this strategy, we compared the recombinant expression, solubility, and suitability for structural analysis by NMR and/or X-ray crystallography for 68 pairs of homologous proteins from E. coli and Thermotoga maritima. A sample suitable for structural studies was obtained for 62 of the 68 pairs of homologs under standardized growth and purification procedures. Fourteen (eight E. coli and six T. maritima proteins) samples generated NMR spectra of a quality suitable for structure determination and 30 (14 E. coli and 16 T. maritima proteins) samples formed crystals. Only three (one E. coli and two T. maritima proteins) samples both crystallized and had excellent NMR properties. The conclusions from this work are: (1) The inclusion of even a single ortholog of a target protein increases the number of samples for structural studies almost twofold; (2) there was no clear advantage to the use of thermophilic proteins to generate samples for structural studies; and (3) for the small proteins analyzed here, the use of both NMR and crystallography approaches almost doubled the number of samples for structural studies.     

Characterization of SPACR, a sialoprotein associated with cones and rods present in the interphotoreceptor matrix of the human retina: immunological and lectin binding analysis

Rod and cone photoreceptors project from the outer retinal surface into a carbohydrate-rich interphotoreceptor matrix (IPM). Unique IPM glycoconjugates are distributed around rods and cones. Wheat germ agglutinin (WGA) strongly decorates the rod matrix domains and weakly decorates the cone matrix domains. This study characterizes the major WGA-binding glycoprotein in the human IPM, which we refer to as SPACR (sialoprotein associated with cones and rods). SPACR, which has a molecular weight of 147 kDa, was isolated and purified from the IPM by lectin affinity chromatography. A polyclonal antibody to SPACR was prepared that colocalizes in tissue preparations with WGA-binding domains in the IPM. Sequential digestion of SPACR with N- and O- glycosidases results in a systematic increase in electrophorectic mobility, indicating the presence of both N- and O-linked glycoconjugates. Complete deglycosylation results in a reduction in the relative molecular mass of SPACR by about 30%. Analysis of lectin binding allowed us to identify some of the structural characteristics of SPACR glycoconjugates. Treatment with neuraminidase exposes Galbeta1- 3GalNAc disaccharide as indicated by positive peanut agglutinin (PNA) staining, accompanied by the loss of WGA staining. Maackia amurensis agglutinins (MAA-1 and MAA-2), specific for sialic acid in alpha2-3 linkage to Gal, bind SPACR, while Sambucus nigra agglutinin (SNA), specific for alpha2-6 linked sialic acid, does not, indicating that the dominant glycoconjugate determinant on SPACR is the O-linked carbohydrate, NeuAcalpha2-3Galbeta1-3GalNAc. The abundance of sialic acid in SPACR suggests that this glycoprotein may contribute substantially to the polyanionic nature of the IPM. The carbohydrate chains present on SPACR could also provide sites for extensive crosslinking and participate in the formation of the ordered IPM lattice that surrounds the elongate photoreceptors projecting from the outer retinal surface.      

The structure, catalytic mechanism and regulation of adenylyl cyclase

The recent structure determinations of the mammalian effector enzyme adenylyl cyclase reveal the structure of its catalytic core, provide new insights into its catalytic mechanism and suggest how diverse signaling molecules regulate its activity.     

Association of 25-Hydroxyvitamin D status and genetic variation in the vitamin D metabolic pathway with FEV1 in the Framingham Heart Study

Background

Vitamin D is associated with lung function in cross-sectional studies, and vitamin D inadequacy is hypothesized to play a role in the pathogenesis of chronic obstructive pulmonary disease. Further data are needed to clarify the relation between vitamin D status, genetic variation in vitamin D metabolic genes, and cross-sectional and longitudinal changes in lung function in healthy adults.

Methods

We estimated the association between serum 25-hydroxyvitamin D [25(OH)D] and cross-sectional forced expiratory volume in the first second (FEV₁) in Framingham Heart Study (FHS) Offspring and Third Generation participants and the association between serum 25(OH)D and longitudinal change in FEV₁ in Third Generation participants using linear mixed-effects models. Using a gene-based approach, we investigated the association between 241 SNPs in 6 select vitamin D metabolic genes in relation to longitudinal change in FEV₁ in Offspring participants and pursued replication of these findings in a meta-analyzed set of 4 independent cohorts.

Results

We found a positive cross-sectional association between 25(OH)D and FEV₁ in FHS Offspring and Third Generation participants (P = 0.004). There was little or no association between 25(OH)D and longitudinal change in FEV₁ in Third Generation participants (P = 0.97). In Offspring participants, the CYP2R1 gene, hypothesized to influence usual serum 25(OH)D status, was associated with longitudinal change in FEV₁ (gene-based P < 0.05). The most significantly associated SNP from CYP2R1 had a consistent direction of association with FEV₁ in the meta-analyzed set of replication cohorts, but the association did not reach statistical significance thresholds (P = 0.09).

Conclusions

Serum 25(OH)D status was associated with cross-sectional FEV₁, but not longitudinal change in FEV₁. The inconsistent associations may be driven by differences in the groups studied. CYP2R1 demonstrated a gene-based association with longitudinal change in FEV₁ and is a promising candidate gene for further studies.

Electronic supplementary material

The online version of this article (doi:10.1186/s12931-015-0238-y) contains supplementary material, which is available to authorized users.