Genetic variation and distances of five Italian native sheep breeds

Genetic distances among five of the most important Italian native sheep breeds were estimated by using gene frequencies of four blood group and seven blood protein loci and by three different computing methods. The values of the three distance matrices were highly correlated. Genetic distances were found within the range values reported in the literature for local breeds. Shorter distances fitted the historical evidence of migrations.     

Evidence for inhibitory SH groups in the thiol activated K:Cl cotransporter of low K sheep red blood cells

The monofunctional thiol reagents N-ethylmaleimide (NEM) and methyl methanethiosulfonate (MMTS) stimulate ouabain resistant (OR) electroneutral K:Cl cotransport in LK sheep red blood cells at low, but not at high concentrations. Diamide (DM), on the other hand, only stimulates OR K:Cl flux (Lauf, P.K., J. Memb. Biol. 101: 179–188, 1988). The DM stimulated K:Cl cotransport was decreased toward the control value prior to DM stimulation when NEM or MMTS were added, subsequently. The inhibitory effect was dependent on the compound's concentration and exposure time and, in the case of MMTS, was reversed upon addition of dithiothreitol (DTT). The inhibition was more prominent when NEM treatment was performed at pH 8.0 and disappeared at pH 6.0. In contrast the NEM stimulatory effect was most effective when the pH of NEM treatment was 6.0 (Bauer, J. & Lauf, P.K., J. Memb. Biol. 73: 257–261, 1983). The results suggest the existence of additional, however, inhibitory thiol groups in the already thiol-activated K:Cl cotransporter, with a different pKa value and a lower affinity for NEM or MMTS as compared to the stimulatory thiol groups. Like the activating thiols, the inhibitory sulfhydryls appeared to be inaccessible to non-penetrating thiol reagents and hence, must be located deeper within the red cell membrane.     

C1q,a collagen-like complement subcomponent,in dermatosparactic cattle: its extracellular modification is not affected by lack of procollagen N-terminal proteinase (pN-proteinase)

C1q, a collagen-like complement protein, was purified from the serum of a ddermatosparactic calf which lacks procollagen N-terminal proteinase (pN-proteinase). The specific hemolytic activity of the serum Clq from the dermatosparactic animal was identical to that of C1q from a normal calf. Gel-filtration of serum from dermatosparactic calf, on Sepharose 6B, showed the presence of C1q-antigenic material at only one position which was identical to the elution position of normal bovine C1q. No differdence, under dissociating conditions, could be seen in the size of the chains of C1q in specific immunoprecipitates isolated from the sera of dermatosparactic and normal animals, as judged by polyacrylamidegel electrophoresis (PAGE) in the presence of sodium dodecyl sulfate (SDS). The C1q from the dermatosparactic animal showed the same N-terminal amino acid and typtic-digest peptide pattern on HPLC as C1q from the normal calf. These results strongly suggest that pN-proteinase is not involved in the extracellular processing of C1q.     

Regulation of Brain and Cerebrospinal Fluid Calcium by Brain Barrier Membranes Following Vitamin D-Related Chronic Hypo- and Hypercalcemia in Rats

Male Fischer-344 rats, 21 days old, were fed diets containing 0 (LOD), 2,200 (CONT), or 440,000 (HID) international units of vitamin D3 per kilogram for 12 weeks. [Ca] was measured in plasma, CSF, brain, and choroid plexus. In addition, 45Ca and 36Cl transfer coefficients (KCa and KCl) for uptake from blood into CSF and brain were determined. Although plasma ionized [Ca]s in LOD and HID rats were 50% and 136%, respectively, of values in CONT animals, CSF and brain [Ca]s ranged from only 85% to 110% of respective CONT values. Choroid plexus [Ca] was increased by 37% after HID diet, but was decreased only 10% after LOD. KCa values at CSF, parietal cortex, and pons-medulla were negatively correlated with plasma ionized [Ca], whereas KCl values at CSF and brain were not different between the diet groups. The findings demonstrate that central nervous system [Ca] is maintained during chronic hypo- or hypercalcemia by saturable transport of Ca at brain barrier membranes. This transport does not seem to involve modulation by 1,25-dihydroxyvitamin D3.     

Transformations and fate of sheep urine-N applied to an upland U.K. pasture at different times during the growing season

The fate of sheep urine-N applied to an upland grass sward at four dates representing widely differing environmental conditions, was followed in soil (0–20 cm) and in herbage. Urine was poured onto 1-m² plots to simulate a single urination in August 1984 (warm and dry), May (cool), July and August 1985 (cool and wet) at rates equivalent to 40–52 g N m⁻². The transformation of urine-N (61–69% urea-N) in soil over a 6–7 week period followed the same general pattern when applied at different times during the season; rapid hydrolysis of urea, the appearance of large amounts of urine-N as ammonium in soil extracts, and the appearance of nitrate about 14 days after application. The magnitude of “apparent” nitrification however differed markedly with environmental conditions, being greatest in May 1985 when a maximum of 76% of the inorganic soil N was in the form of nitrate. At all other application dates nitrate levels were relatively low. With the August 1984 application soil inorganic N returned to control levels (given water only) after 31 days but considerable amounts remained in soil for 60–90 days with the other applications. Weekly cuts to 3-cm indicated that increases in herbage dry matter and N yields in response to urine application were greatest in absolute terms after the May 1985 application and continued for at least 70 days with all applications. Relative to control plots the May application resulted in a 3-fold increase in herbage DM compared with corresponding values of 6-, 5-, and 7-fold increases with the August 1984, July and August 1985 applications. Recovery of urine-N in herbage was poor averaging only 17% of that applied at different dates, while recovery in soil extracts was incomplete. The exact routes of loss (volatilisation, leaching, denitrification or immobilisation) were not quantified but it is evident that substantial amounts of urine-N can be lost from the soil-plant system under upland conditions.     

Immunohistochemical localization of keratin in bull,goat, and sheep anterior pituitary glands

Summary Immunohistochemical localization of keratin, an intermediate filament protein, was studied in bull, goat, and sheep anterior pituitary glands, i.e., in animals of the order Artiodactyla. Strong immunoreactivity was detected in the cells of the marginal layer of bull and goat, as well as in cysts or large follicles in the anterior lobe of all 3 species. In addition, a number of stellateshape cells were immunoreactive for keratin and were distributed throughout the anterior lobe. The localization of keratin-positive cells in light-microscopic preparations correlated precisely with the localization of folliculo-stellate cells in adjacent ultrathin sections. In ultrastructural studies, many slender and elliptical membranous components which were different from smooth endoplasmic reticulum were observed in the cytoplasm of the some keratin-positive cells. Some of the folliculostellate cells in the 3 species were also immunoreactive for the subunit of S-100 protein, which exists in some epithelial cells. On the other hand, immunolocalization of glial fibrillary acidic protein, a glial cell marker, could not be demonstrated in the anterior pituitary glands of the 3 species studied. These results suggest that keratin-positive folliculo-stellate cells express epithelial-like characteristics.     

Blood-brain exchange routes and distribution of65Zn in rat brain

Zinc is essential for normal development and function of the CNS although much is to be learned about brain Zn homeostasis. In these experiments adult male Wistar rats within the weight range 500–600 g were used. Ventriculo-cisternal perfusion was performed to allow the measurement of⁶⁵Zn fluxes between blood and csf across the choroid plexuses. Blood-brain or blood-cerebrospinal fluid barrier permeability to⁶⁵Zn has been determined by graphical analysis in experiments that lasted between 5 and 180 minutes. Cerebral capillary permeability to⁶⁵Zn was found to be low with a K_in of about 5×10^–4ml/min/g. Choroid plexus permeability to⁶⁵Zn was about 12 fold greater, although Zn influx to brain via this route was <5% that across cerebral capillaries. The autoradiographic distribution of⁶⁵Zn in brain showed regional variation with lowest levels in white matter and high levels in the dentate gyrus and hippocampus.     

Morphometric investigations of the colon mucosa in chronicTrypanosoma cruzi infected rats

The objective of this investigation was to study the morphometry of the epithelial mucosa in the chronic phase ofT. cruzi infection. Nine young female Wistar rats were inoculated withT. cruzi. Ten months after inoculation the animals were sacrificed and the proximal colon was collected for morphometric measurements of the thickness of the muscle layers, the number of neurons in the myenteric plexus, the crypt cell population (CCP), crypt cell production per crypt (CCPC) and turnover time (TT) of the epithelium. There was no muscle layer hypertrophy but there was significant denervation in the group inoculated withT. cruzi, which also showed hyperplasia of the epithelium. The data suggest that denervation of the myenteric plexus did not induce hypertrophy of the propria muscle layer itself but altered the morphometry of the colonic epithelium inT. crwzi-infected animals, with increased development of CCP and TT. It is possible that this epithelial hyperplasia, as a consequence of a longer crypt cell TT, increased the absorption and secretion activities of the colon, which in turn may participate in the genesis of the enteromegalies observed in the chronic phase of Chagas’ Disease.     

Leukotriene C4 Transport and Metabolism in the Central Nervous System

The transport and metabolism of radiolabeled leukotriene (LT) C4 in the CNS were investigated after intraventricular injection. Under thiopental (Pentothal) anesthesia, New Zealand white rabbits were injected intracerebroventricularly with 0.2 ml of artificial CSF containing 2.5 microCi of [3H]LTC4 (36 Ci/mmol), 0.3 microCi of [14C]mannitol, and, in some cases, 0.9 mg of probenecid, 1.8 mg of cysteine, 1.4 micrograms of unlabeled LTC4, or 2 mg of tolazoline HCl. After 2 h, the conscious rabbits were killed, and the quantity and nature of the 3H and 14C were determined in CSF, choroid plexus, and brain. The [3H]LTC4 recovered in CSF and brain was not extensively metabolized, as greater than 70% of the 3H remained [3H]LTC4, although some spontaneous conversion to 11-trans-[3H]LTC4 occurred. Oxidized forms of [3H]LTC4, [3H]LTD4, and [3H]LTE4 did not exceed 18% in CSF and brain. After intraventricular injection of [3H]LTC4, 3H was transferred from the CSF to blood by a probenecid-sensitive, but tolazoline-insensitive, transport system in the CNS much more rapidly than mannitol. Cysteine decreased the retention of [3H]LTC4 in brain. These results are consistent with previous in vitro observations that [3H]LTC4 is transferred from CSF into blood by an efficient transport system for LTC4 in choroid plexus.     

Attempts to probe the antigens and protective immunogens of Trichostrongylus colubriformis in immunoblots with sera from infected and hyperimmune sheep and high- and low-responder guinea pigs

Comparison of antisera from sheep during primary infection and following vaccination and challenge with Trichostrongylus colubriformis, with antisera obtained following primary infection of high- and low-responder guinea pigs, failed to reveal different antigenic patterns in proteins separated from fourth stage larval extracts by two-dimensional electrophoresis and probed by the immunoblot technique.Generally, serum IgG reacted specifically with worm antigens of mol. wt greater than 94,000, whereas protection against challenge infection was elicited most effectively in the guinea pig by fractions in the 67,000–94,000 range.Most distinct separations of larval proteins by SDS-polyacrylamide gel electrophoresis were obtained by extraction of live larvae and the extracts used within 2–3 days.