Cooperation of v-jun and v-erbB oncogenes in embryo fibroblast transformation in vitro and in vivo.

Retroviral vectors carrying either the v-jun and v-erbB sequences or the v-jun gene linked to the neomycin resistance gene were constructed on the basis of the structural genome organization of avian erythroblastosis virus (AEV). These viruses, called JB and JN, respectively, were rescued as Rous-associated virus-1 pseudotypes, and they were shown to successfully transform chicken embryo fibroblasts in vitro. However, in agar, colonies developed from JB-infected fibroblasts were three to five times larger than those obtained after infection with JN or with AEV Pst124 carrying only a functional v-erbB gene. In vivo, on chorioallantoic membrane (CAM) assays, JB produced fibrosarcomas that were more rapidly growing and much larger than those induced by JN or AEV Pst124. Moreover, in chickens infected in ovo with JB, multiple fibrosarcomas arose in different organs a few days after birth, whereas no tumor could be detected in parallel experiments in either JN- or AEV Pst124-infected animals. These results demonstrate that in embryo fibroblast cells, v-jun and v-erbB can act synergistically to enhance the transformation potential of either oncogene alone both in vitro and in vivo.     

Uptake of lysine and prolinevia separate α-neutral amino acid transport pathways inMytilus gill brush border membranes

Summary Brush border membrane vesicles (BBMV) were prepared from the gills of the marine mussel,Mytilus edulis. These membranes contained two distinct pathways for cotransport of Na⁺ and -neutral amino acids. The major pathway in mussel gill BBMV was the alanine-lysine (AK) pathway, which had a high affinity for alanine and for the cationic amino acid, lysine. The AK pathway was inhibited by nonpolar -neutral amino acids and cationic amino acids, but was not affected by -neutral amino acids or imino acids. The kinetics of lysine transport were consistent with a single saturable process, with aJ _max of 550 pmol/mg-min and aK _t of 5 m. The AK pathway did not have a strict requirement for Na⁺, and concentrative transport of lysine was seen in the presence of inwardly directed gradients of Li⁺ and K⁺, as well as Na⁺. Harmaline inhibited the transport of lysine in solutions containing either Na⁺ or K⁺. The alanine-proline (AP) pathway transported both alanine and proline in mussel gill BBMV. The AP pathway was strongly inhibited by nonpolar -neutral amino acids, proline, and -(methylamino)isobutyric acid (Me-AIB). The kinetics of proline transport were described by a single saturable process, with aJ _max of 180 pmol/mg-min andK _t of 4 m. In contrast to the AK pathway, the AP pathway appeared to have a strict requirement for Na⁺. Na⁺-activation experiments with lysine and proline revealed sigmoid kinetics, indicating that multiple Na⁺ ions are involved in the transport of these substrates. The transport of both lysine and proline was affected by membrane potential in a manner consistent with electrogenic transport.     

Catabolite repression of the synthesis of inducible polygalacturonase and pectinesterase byAspergillus niger sp.

Several recent reports have described large numbers of monoclonal antibodies that cross-react with toxins A and B ofClostridium difficile; this suggests that the toxins share major epitopes. Our results show that monoclonal antibodies (MAb) against other antigens bind nonspecifically to both toxins. Therefore, we believe that the cross-reacting MAb bind by this manner and not by a true immune reaction.     

An evolutionarily conserved enzyme degrades transforming growth factor- alpha as well as insulin

A single enzyme found in both Drosophila and mammalian cells is able to selectively bind and degrade transforming growth factor (TGF)-alpha and insulin, but not EGF, at physiological concentrations. These growth factors are also able to inhibit binding and degradation of one another by the enzyme. Although there are significant immunological differences between the mammalian and Drosophila enzymes, the substrate specificity has been highly conserved. These results demonstrate the existence of a selective TGF-alpha-degrading enzyme in both Drosophila and mammalian cells. The evolutionary conservation of the ability to degrade both insulin and TGF-alpha suggests that this property is important for the physiological role of the enzyme and its potential for regulating growth factor levels.     

Reduced productivity in adult yellowfever mosquito (Diptera: Culicidae) populations

Male and female Aedes aegypti (L.) mosquitoes of the laboratory strain ROCK were irradiated with 130 mw of argon 514.5 nm laser microbeams for 0.04, 0.25, 0.4, and 0.5 s, respectively. Egg production, percentage hatch, and productivity (average number of adults surviving after 3 wk) were used to assess mutagenic effects. Mortality was high for males in all laser radiation groups and increased with time of exposure. Except for the group treated for 0.25 s, significant reductions in total F1 progeny also were demonstrated for all other experimentals when male parents were exposed to laser radiation. Females showed a high mortality when subjected to 0.4- and 0.5-s laser radiation. No F1 progeny were produced when parental females were exposed for 0.25, 0.4, and 0.5 s. Numbers of F1 progeny from females exposed to 0.04 s of laser radiation were significantly reduced. A comparison of weekly mean number of progeny showed that the important differences in productivity occurred during the first and second week, respectively, when either male or female adult parents were subjected to laser radiation.     

Effect of Escherichia coli endotoxin on ascorbic acid transport in isolated adrenocortical cells

The active uptake of ascorbic acid by isolated rat adrenocortical cells increases with ascorbic acid concentration, depends on time and calcium, and is inhibited by ACTH concentrations required for maximal steroidogenesis. Lipopolysaccharide of Escherichia coli 0111:B4 modifies the ascorbic acid uptake in a calcium-dependent manner. At low calcium concentrations, lipopolysaccharide exerts a stimulatory effect on ascorbic acid transport and at high concentrations lipopolysaccharide produces a dose-dependent inhibitory effect. This inhibition of the ascorbic acid transport by the endotoxin can alter the ascorbic acid accumulation in the adrenal gland during endotoxin shock.     

Progesterone determinations and clinical examinations of reproductive organs in purebred and crossbred female Zebu cattle

Five experiments were undertaken to investigate variation in progesterone concentrations as related to the collection and handling of samples of milk and blood, to determine reference values for progesterone and to evaluate clinical findings in relation to progesterone data from pure- and crossbred Zebu cattle reared in the Peruvian tropics. Whole-milk progesterone concentrations obtained from 12 Holstein x Nellore pregnant cows at hourly intervals over a 24-h period were highest immediately after milking; this peak was followed by a sharp drop over the next 3 h. Milk-fat content from 28 Brown Swiss x Nellore pregnant cows increased from 2.4% before milking to 6.7% afterwards (P < 0.05), whereas progesterone concentrations in whole milk increased from 18.4 to 59.5 nmol/1 (P < 0.05). Progesterone concentrations in fat-free milk were stable, with the exception of the fore-milk sample, which was lower than subsequent samples collected during milking (P < 0.05). Blood samples collected from 23 purebred, pregnant Nellore cows, were divided into four aliquots, and plasma and serum were harvested periodically over the next 120 h of storage at +4 degrees C, or in the shade at ambient air temperatures. The results indicate that blood samples can be stored unseparated at both temperatures studied for up to 3 h without severe loss of progesterone. Milk samples collected at different intervals during the luteal phase of the estrous cycle and during early and mid-pregnancy from crossbred cows showed no significant differences in progesterone concentrations between Days 9 to 13 of the cycle and Days 9 to 13 of gestation. Progesterone levels during advanced gestation were higher (P < 0.05). Out of 2,607 clinical examinations, the level of agreement between palpatory findings and progesterone determinations was 95.6 and 81.9% in diagnosing non-luteal and luteal structures, respectively. Significant differences in the level of agreement between palpators were found (P < 0.01). It is concluded that milk samples, preferably composite milk or strippings, must be consistently collected at the same stage of milking, and that centrifugation of blood samples should be done as soon as possible and not later than 3 h after collection.     

Milk progesterone profiles in crossbred Brown Swiss x Nellore cattle following natural service

Ovarian activity and estrous behaviour were monitored through milk progesterone determinations and twice daily visual observations in 70 crossbred Brown Swiss x Nellore cows following natural service. Whole milk samples were collected on the day of estrus (Day 1), Day 11, and every 5 d thereafter until the next estrus or pregnancy confirmation. Seventy percent of the cows behaved as expected, i.e. they showed a 19-to 25-d interval between estrus and the next ovulation, or they became pregnant. Estrous cycles of regular length (18 to 24 d) were found in 54% of the cases. Prolonged luteal phases (interval from estrus to next ovulation > 28 d) were found in 15.7% of cows. Short estrous cycles (interestrous interval < 18 d) were found in 7.1% of the cases. Periods of acyclicity (basal progesterone levels for periods >/= 15 d) were found in 5.8% of the cases, and one cow exhibited estrus while pregnant and had a high progesterone concentration. Cows with a prolonged luteal phase and those with a short estrous cycle had an interval between ovulations of 35.0 +/- 6.7 d (x +/- SD) and 9.6 +/- 3.1 d, respectively. Signs of estrus were not detected in 33.3% of the ovulations confirmed by progesterone determinations. Low conception rates, failures in estrus detection and a high frequency of abnormal postbreeding luteal phases were found.     

Long-acting estrogenic responses of estradiol fatty acid esters

Estradiol esters at C-17 and C-3 with palmitic, stearic and oleic acids were chemically synthesized and then evaluated for their long-acting estrogenic responses in ovariectomized rats. The duration of the biological effects was measured after a single subcutaneous dose of 0.1 mumol of each ester and compared with those observed with 17 beta-estradiol, estradiol 3-benzoate and estradiol 17-enanthate. Vaginal citology, uterophyc action, serum gonadotropins inhibition and 17 beta-estradiol levels were measured 0, 5, 10, 20, 30 and 60 days after injection. The results disclosed that most of the estradiol derivatives evaluated exhibited a long-acting estrogenic action. However, the monoesters at C-17 showed longer effects that monoesters at C-3, while the estradiol diesters exhibited the shortest effects. In addition as shown by its low serum levels, all estradiol esters with unsaturated fatty acids show a decreased E2 absorption. The overall results indicated that esterification of E2 with long chain fatty acids provided long-acting properties to it, being higher with C-17 esters. Whether some of these compounds could be employed in substitutive endocrine therapy remains to be established.