Oxytocin and bovine parturition: a steep rise in endometrial oxytocin receptors precedes onset of labor.

Oxytocin receptors were measured in myometrium and intercaruncular endometrium of cows during pregnancy and parturition. Concentrations of estradiol-17 beta, estrone, and progesterone in peripheral blood were also measured. Receptor concentrations in the endometrium rose almost 200-fold from Day 20 to term (p < 0.0001, ANOVA), from 40 +/- 11 to 7300 +/- 1430 fmol/mg protein. Myometrial receptor concentrations increased 10-fold from 180 +/- 36 fmol/mg on Day 20 to 1850 +/- 360 fmol/mg protein at term (p < 0.0001, ANOVA). During labor, endometrial receptors (6600 +/- 1300 fmol/mg) remained at prelabor values, whereas myometrial receptor concentrations had decreased to 1190 +/- 316 fmol/mg (not significant) and declined further postpartum. Plasma concentrations of progesterone declined from 4-5 ng/ml to about 2 ng/ml between Days 250 and 282 and dropped to < 0.2 ng/ml shortly before delivery. Plasma concentrations of estrone and estradiol-17 beta were below 10-20 pg/ml until Day 230. Estrone concentrations were significantly (p < 0.05) increased by Day 250 and estradiol-17 beta by Day 270, and then both rose rapidly. During labor, plasma estrone was 1135 +/- 245 pg/ml and plasma estradiol-17 beta was 226 +/- 131 pg/ml. The molar ratio of estrone and estradiol-17 beta to progesterone rose from less than 0.01 to 4.4 during labor, and was correlated with oxytocin receptor concentrations in endometrium (r = 0.5160, p < 0.001), but not those in myometrium (r = 0.0122). The regulation of oxytocin receptors by ovarian hormones in the two tissues may therefore differ.(ABSTRACT TRUNCATED AT 250 WORDS)     

Methane oxidation by methanotrophs and its effects on the phosphate flux over the sediment-water interface in a eutrophic lake

The effect of methane oxidation in aerobic sediment on oxygen consumption and phosphate flux was investigated in diffusion chambers. The diffusion chambers consisted of two compartments separated by a Teflon membrane. In the upper chamber a thin sediment layer was present and the lower chamber was continuously flushed with gas. The hydrophobic membrane allowed for diffusion of gases from the lower chamber through the sediment layer toward the headspace of the upper chamber. In experiments with a methane oxidation rate of 9.8 mmol m^–2 day^–1, the oxygen consumption rate increased by a factor of two compared with controls without methane oxidation (8.6 vs 17.7 mmol m^–2 day^–1). Methane oxidation significantly decreased oxygen penetration depth (2.5–4.0 vs 1.0–2.0 mm). However, despite the shrinkage of the oxidized microlayer, no differences were found in phosphate flux across the sediment water interface. Batch experiments with standard additions of methane revealed that the growth of methanotrophic bacteria contributes to the phosphate uptake of aerobic sediment. From the batch experiments a molar ratio of carbon to phosphate of 45 mol:mol was calculated for the growth of methanotrophs. Results suggest that a decrease in chemical phosphate adsorption caused by a decrease in the oxygen penetration depth could be compensated for entirely by the growth of methanotrophic bacteria. Send offprint requests to: A.J.C. Sinke     

Acetaldehyde-collagen adducts in CCl4-induced liver injury in rats

Circulating AC levels as well as antibodies against AC-protein adducts are increased in non-alcoholic liver injury. To identify the adducts, we used rats with CCl4-induced cirrhosis. Liver subcellular fractions were analyzed by immunochemical staining of protein slot blots and of electrophoretically separated proteins, transferred to nitrocellulose, using AC-protein adduct-specific antibodies. One reactive protein of about 200 kD was detected in the liver soluble fraction and in the cytosol of isolated hepatocytes and, to a lesser extent in the liver microsomes of CCl4-treated rats; in control animals, this reactivity was much weaker. The immunopositive AC adduct co-migrated with the beta 1,2 dimer of rat collagen type I; it was sensitive to digestion by a highly purified collagenase and also reacted with anti-rat collagen type I-specific IgG. In addition, comparison of peptides of the CNBr-digested, immunoprecipitated AC adduct with those of rat collagen type I revealed a high degree of similarity. Thus, AC adduct formation occurs in liver injury of non-alcoholic origin, and a target protein appears to be related to collagen type I, most likely the procollagen precursor.     

A locus for familial hypertrophic cardiomyopathy is closely linked to the cardiac myosin heavy chain genes, CRI-L436, and CRI-L329 on chromosome 14 at q11-q12

We report that a gene responsible for familial hypertrophic cardiomyopathy (HC) is closely linked to the cardiac alpha and beta myosin heavy chain (MHC) genes on chromosome 14q11. We have recently shown that probe CRI-L436, derived from the anonymous DNA locus D14S26, detects a polymorphic restriction fragment that segregates with familial HC in affected members of a large Canadian family. Using chromosomal in situ hybridization, we have mapped CRI-L436 to chromosome 14 at q11-q12. Because the cardiac MHC genes also map to this chromosomal band, we have determined the genetic distances between the cardiac beta MHC gene, D14S26, and the familial HC locus. Data presented here show that these three loci are linked within 5 centimorgans on chromosome 14 at q11-q12. The possibility that defects in either the cardiac alpha or beta MHC genes are responsible for familial HC is discussed.     

Nutritional criteria in machiguenga food production decisions: A linear-programming analysis

Machiguenga Indians of the Peruvian Amazon, like other low populationdensity, technologically “simple” peoples, produce ample food for a nutritious diet. Assuming that this is an intended outcome of their foodproduction strategy, to what extent is it a labor-efficient solution to the problem of producing a “balanced diet”? A linear-programming model of the “diet problem” is constructed with parameters reflecting the Machiguenga economy, and solutions are computed. These are then compared to observed Machiguenga food production; the degree of fit between model and behavior is examined and reasons for discrepancies are discussed.     

Cloning and expression of the Bacillus subtilis phage SPP1 in E. coli. I. Construction and characterization of lambda/SPP1 hybrids

Summary We have constructed /SPP1 hybrid phages by in vitro ligation of EcoRI fragments of the Bacillus subtilis phage SPP1 DNA to a lambdoid bacteriophage vector. EcoRI digestion of SPP1 generated 15 DNA fragments of which 13 could be cloned. The SPP1 DNA of such hybrids was stably maintained and replicated in Escherichia coli, as indicated by marker rescue experiments in B. subtilis. EcoRI fragment 1 of SPP1 could not be cloned although subfragments of fragment 1 resulting from spontaneous deletions which occurred during the cloning regime were consistently obtained. A region within EcoRI fragment 1 responsible for its incompatibility with replication in E. coli was defined by these experiments.Part of this work was taken from the doctoral thesis of E.P.A. submitted to the Freie Universität, Berlin 1979     

Uterotropic activity of cis and trans isomers of zearalenone and zearalenol.

The cis and trans isomers of zearalenone [2,4-dihyroxy-6-(10-hydroxy-6-oxo-1-undecenyl)-benzoic acid mu-lactone] and zearalenol [2,4-dihydroxy-6-(6,10-dihydroxy-1-undecenyl)-benzoic acid mu-lactone] were tested for uterotropic activity in the white rat. The metabolites were administered through the oral route (per os) and by topical application to the freshly shaven skin on the back. cis-Zearalenone was significantly more active than trans when fed orally to the rats in the diet or when applied topically by skin application. However, the cis isomer of zearalenol was not significantly different than its trans isomer. trans-Zearalenone was less active than trans-zearalenol.     

Citrate lyase from Streptococcus diacetilactis

Citrate lyase (EC 4.1.3.6) was purified 38-fold from cell-free extracts of Streptococcus diacetilactis. The enzyme was homogeneous in analytical ultracentrifugation and polyacrylamide gel electrophoresis The final enzyme preparation contained acetate: HS-citrate lyase ligase—an acetylating enzyme which converts inactive HS-citrate lyase into enzymatically active acetyl-S-citrate lyase. This enzyme activity was purified 25-fold over the crude extract and seemed to be associated with citrate lyase. Partially purified citrate lyase from Leuconostoc citrovorum contained also its acetylating enzyme. Purified citrate lyases from Klebsiella aerogenes and Rhodopseudomonas gelatinosa were devoid of acetylating enzyme activity. The HS-form of citrate lyase from S. diacetilactis was completely acetylated and hence activated by incubation with ATP and acetate for 25 min at 25° C. The enzyme did not acetylate the HS-lyases from R. gelatinosa and K. aerogenes. In contrast to the citrate lyases from R. gelatinosa and K. aerogenes the enzymes from S. diacetilactis and L. citrovorum showed onlya very weak reaction inactivation. It is assumed that this is due to the association of the acetylating enzymes with these lyases.     

Navigating the plant cell: intracellular transport logistics in the green kingdom

Intracellular transport in plant cells occurs on microtubular and actin arrays. Cytoplasmic streaming, the rapid motion of plant cell organelles, is mostly driven by an actin–myosin mechanism, whereas specialized functions, such as the transport of large cargo or the assembly of a new cell wall during cell division, are performed by the microtubules. Different modes of transport are used, fast and slow, to either haul cargo over long distances or ascertain high-precision targeting, respectively. Various forms of the actin-specific motor protein myosin XI exist in plant cells and might be involved in different cellular functions.