Artificial insemination of subtropical commercial beef cattle following synchronization with cloprostenol (ICI 80996): I. Fertility

Two trials were conducted over a two-year period with 519 cycling Bos taurus x Bos indicus heifers and cows. The objectives of these trials were: 1) To compare fertility of artificial insemination at the cloprostenol-induced estrus and the naturally occurring estrus, 2) To evaluate the fertility of artificial insemination at a predetermined time (Timed AI) following an estrous synchronization regime with cloprostenol (CLP) and 3) To define the optimum interval from a second CLP treatment for Timed AI. In Trial I, 128 animals were assigned to four treatments: 1) Controls, which were inseminated at the natural occurring estrus; 2) timed AI at 72 hr and again at 96 hr post-second CLP; 3) Timed AI at 72 hr post-second CLP and 4) AI at the CLP-induced estrus. Trial II included 391 heifers distributed among six treatments; 1) Timed AI between 70 and 90 hr post-second CLP; 2) Sham AI between 70 and 90 hr post-second CLP, 3) Chute Stress between 70 and 90 hr post-second CLP; 4) AI at the CLP-induced estrus; 5) Control-AI at the naturally occurring estrus and 6) Non-treated and exposed to fertile bulls. The fertility of the animals artificially inseminated at the CLP-induced estrus was similar to that of insemination at the naturally occurring estrus in Trial I and Trial II (30 vs 46%; 37 vs 38%, respectively). The first service pregnancy rates of the animals bred at a predetermined time were similar to those bred at the CLP-induced estrus in Trial I, but lower in Trial II (P < .01).     

Dramatic size variation of yeast mitochondrial RNAs suggests that RNase P RNAs can be quite small

The gene coding for the AU-rich RNA required for mitochondrial RNase P activity in Saccharomyces cerevisiae codes for a 490-base RNA while that in Candida glabrata codes for a 227-base RNA. We have detected a 140-nucleotide RNA coded by the mitochondrial DNA from Saccharomycopsis fibuligera by hybridization with an oligonucleotide complementary to a conserved sequence found in mitochondrial and prokaryotic RNase P RNAs. DNA sequence analysis of the mitochondrial DNA from the region coding for this RNA revealed a second conserved sequence block characteristic of RNase P RNA genes and the presence of a downstream tRNA(Pro) gene. Like previously characterized mitochondrial RNase P RNAs, this small RNA is extremely AU-rich. The discovery of this 140-base RNA suggests that naturally occurring RNase P RNAs may be quite small.     

On the location and function of tyrosine beta 331 in the catalytic site of Escherichia coli F1-ATPase.

1) Using a combination of site-directed mutagenesis and fluorescence spectroscopy we have studied the location and function of residue beta Y331 in the catalytic site of Escherichia coli F1-ATPase. The fluorescent analog lin-benzo-ADP was used as a catalytic-site probe, and was found to bind to three sites in normal F1, with Kd1 = 0.20 microM and Kd2,3 = 5.5 microM. lin-Benzo-ATP was a good substrate for hydrolysis. 2) The mutants investigated were beta Y331F, L, A and E. kcat/KM for ATP hydrolysis in purified F1 was reduced according to the series Y greater than or equal to F greater than L greater than A greater than E, with E being severely impaired; concomitant decreases in binding affinity for lin-benzo-ADP were seen. 3) Fluorescence properties of lin-benzo-ADP bound to F1 differed widely, depending on the residue present at position beta 331. Red shifts of excitation and emission spectra occurred with F and L residues, but not with Y, A, or E. There was strong quenching of fluorescence with wild-type (Y), partial quenching with A, and no quenching with F, L, or E. 4) We conclude that (a) the environment around the bound adenine moiety in the catalytic site is nonpolar, (b) residue beta 331 is part of the adenine-binding subdomain and when tyrosine is the residue, the phenolic hydroxyl makes direct interaction with the fluorophore, (c) an aromatic residue is not absolutely required at position beta 331 for catalytic function, but an increase in polarity leads to functional impairment, and (d) in terms of fluorescence response of bound lin-benzo-ADP all three catalytic sites behaved the same. 5) F1 from mutant beta Y297F bound lin-benzo-ADP with the same fluorescence and binding characteristics as normal F1, and catalytic properties were similar to normal. Therefore, there was no reason to conclude that residue beta Y297 is involved in binding the adenine moiety of ATP.     

Eosin Y staining of proteins in polyacrylamide gels.

A staining method is described in which various proteins in polyacrylamide gels can be stained by using eosin Y. After a brief incubation of a polyacrylamide gel in an acidic solution of 1% eosin Y, various proteins, including human erythrocyte membrane sialoglycoproteins which are not detectable by Coomassie blue R-250 (CB), can be detected with a sensitivity of 10 ng protein. This is far more sensitive than CB staining and is comparable to the sensitivity of silver staining. In a Western blot, the antigenicity of an eosin Y stained protein is retained. In addition, proteins on an immunoblot sheet can be detected by eosin Y staining. The method described is rapid, sensitive, and reproducible with various proteins in polyacrylamide gels and has the added advantage of also staining sialoglycoproteins.     

Gonadotropin-releasing hormone secretion during the postpartum anestrous period of the ewe

An increase in episodic release of LH is putatively the initial event leading to the onset of postpartum ovarian cyclicity in ewes. This experiment was conducted to determine the relationship between hypothalamic release of GnRH and onset of pulsatile secretion of LH during postpartum anestrus. Control ewes (n = 7) were monitored during the postpartum period to determine when normal estrous cycles resumed. In controls, the mean interval from parturition to the first postpartum estrus as indicated by a rise in serum progesterone greater than 1 ng/mg was 25.8 +/- 0.6 days. Additional ewes (n = 4-5) at 3, 7, 14, and 21 days postpartum (+/- 1 day) were surgically fitted with cannula for collection of hypophyseal-portal blood. Hypophyseal-portal and jugular blood samples were collected over a 6- to 7-h period at 10-min intervals. The number of GnRH pulses/6 h increased (p less than 0.05) from Day 3 postpartum (2.2 +/- 0.5) to Days 7 and 14 (3.6 +/- 0.2 and 3.9 +/- 0.4, respectively). A further increase (p less than 0.05) in GnRH pulse frequency was observed at Day 21 postpartum (6.4 +/- 0.4 pulses/6 h). Changes in pulsatile LH release paralleled changes observed in pulsatile GnRH release over Days 3, 7, 14, and 21 postpartum (0.83 +/- 0.3, 2.8 +/- 0.4, 2.9 +/- 0.6, and 4.0 +/- 1.1 pulses/6 h, respectively). GnRH pulse amplitude was higher at Day 21 than at Days 3, 7, or 14 postpartum. These findings suggest that an increase in the frequency of GnRH release promotes the onset of pulsatile LH release during postpartum anestrus in ewes.     

In vivo degradation of oxidized, regenerated cellulose

Oxidized, regenerated cellulose (ORC) was surgically implanted on the uterine horns of rabbits, and its biodegradation was studied in vivo. Samples of peritoneal lavages, serum, and urine were collected during the degradation process and analyzed for carbohydrate components utilizing high-performance liquid chromatography with pulsed amperometric detection (h.p.l.c.-p.a.d.). Degradation was rapid, and oligomeric products were evident primarily in the peritoneal fluid from the implantation site, with no apparent accumulation in either the serum or the urine. The size distribution and the amount of the oligomeric products decreased after day one, and by day four peritoneal lavages were essentially free of oligomers. The structure of the products formed was consistent with the lability of the polymer in solution, and the kinetics of degradation paralleled the results of the previously reported in vitro studies. Rabbit peritoneal macrophages, when incubated with ORC in vitro were observed to readily ingest and hydrolyze the polymeric material. A mechanism of degradation consisting of chemical depolymerization, followed by enzymatic hydrolysis mediated by glycosidases endogenous to peritoneal macrophages, is proposed.     

Androstenedione, dehydroepiandrosterone and testosterone in ovarian vein plasma and androstenedione in peripheral arterial plasma during the bovine oestrous cycle

Catheters were placed in the carotid artery via a facial artery (n = 12) and in the ovarian vein (n = 12), and, in conjunction, electromagnetic flow meters were placed around the ovarian artery (n = 6) in cyclic beef cows. Androstenedione was quantitatively the highest and dehydroepiandrosterone the lowest of the ovarian androgens measured. Ovarian androgens were correlated positively with each other (P less than 0.05) but not with ovarian blood flow or day of the cycle. There was a trend for spikes of androgen release (ovarian vein concentration x ovarian blood flow) from the ovary to be greatest during the period of decreasing progesterone and CL regression. However, only with testosterone were spikes of release different (Days--13 to--9 less than Days -8 to -4; P less than 0.05; Day 0 = oestrus). The dynamic changes in ovarian androgens noted in this study were compatible with the concept of continuous follicular development and atresia throughout the oestrous cycle.     

Organic acid production from CO2/H2 and CO/H2 by mixed-culture anaerobes

The gases CO, CO₂, and H₂ were used as substrates in anaerobic fermentations producing organic acids. Various mixed bacterial sources were used, including sewage sludge digester effluent, rabbit feces, and soil. Nonsterile microorganism selection was carried out using CO₂/H₂ and CO/H₂ as the primary carbon and energy sources. Cultures were grown in specially designed, high-pressure (to 70 psig) flasks. Methanogenic bacteria were eliminated from the cultures. Liquid products of the fermentations were acetic through caproic acids, with the even-numbered acids predominating. Carbon balances showed conclusively that acetic acid was formed from carbon contained in the CO or CO₂ feed gas. Measurements made included rates of acid product formation, cell density, and degree of gas utilization. Limited characterization of the microorganisms was also performed. Production of organic acids by mixed culture inocula from CO₂/H₂ or CO/H₂ had not been reported previously. Application of this work is to the production of organic chemicals from synthesis gas (SNG), produced by the gasification of fossil fuels (peat, lignite, and various ranks of coals), biomass (agricultural and forest residues, and various biomass crops grown expressly for energy recovery), and municipal solid waste.     

Colonization of artificial substrates by stream insects: Influence of substrate size and diversity

A field experiment was performed in a New Mexico (U.S.A.) stream to investigate the relation between size and diversity of substrate and numbers and diversity of colonizing insects. Baskets with either small gravel, large gravel, or a 1 : 1 mixture of the two sizes were placed in a riffle area and colonization was monitored for 19 days.Colonization was rapid, and both total number of individuals and number of species colonizing the substrates had stopped increasing by the end of the experiment. Fewer individuals colonized baskets downstream, suggesting that the drift is a major source of insect colonists. Small substrate supported more individuals and more species than the larger stones. Total number of individuals and the number of species on the mixed substrate were between numbers on small and large substrate. These results do not support previous generalizations on the relation between substrate size and complexity and the structure of invertebrate communities in streams. Results of the study are compared with the findings of recent experimental studies and it is suggested that earlier generalizations on the role of substrate size and complexity need to be reexamined.Order of authors was determined by the flip of a coin. Reprint requests may be sent to either author.