Multivesicular nuclear body in sertoli cells of the lesser mouse deer, Tragulus javanicus.
(73/548)
The Sertoli cell of the lesser mouse deer, Tragulus javanicus, was examined using light and transmission electron microscopy. Similar to other ruminants, a multivesicular nuclear body (MNB) and laminated smooth endoplasmic reticulum (sER) were observed in the lesser mouse deer Sertoli cell. The MNB was present within the Sertoli cell nucleus, and consisted of vesicles, irregular tubules and ribosome-like structures. It was infrequent in the lesser mouse deer, which differs from domestic ruminants. Vesicles and irregular tubules seem to contain some materials with low and/or middle electron density, and be surrounded by electron dense materials. The diameter of vesicles was between 30 nm and 180 nm. Since the MNB, though less developed compared to that of bulls and goats, was present even in the Sertoli cell nucleus of the primitive ruminant-lesser mouse deer, it should be a common structure of ruminant Sertoli cells. (+info)
Distribution of intimin subtypes among Escherichia coli isolates from ruminant and human sources.
(74/548)
The intimin gene eae, located within the locus of enterocyte effacement pathogenicity island, distinguishes enteropathogenic Escherichia coli (EPEC) and some Shiga toxin-producing E. coli (STEC) strains from all other pathotypes of diarrheagenic E. coli. EPEC is a leading cause of infantile diarrhea in developing countries, and intimin-positive STEC isolates are typically associated with life-threatening diseases such as hemolytic-uremic syndrome and hemorrhagic colitis. Here we describe the development of a PCR-restriction fragment length polymorphism (RFLP) assay that reliably differentiates all 11 known intimin types (alpha1, alpha2, beta, gamma, kappa, epsilon, eta, iota, lambda, theta, and zeta) and three new intimin genes that show less than 95% nucleotide sequence identity with existing intimin types. We designated these new intimin genes Int- micro, Int-nu, and Int-xi. The PCR-RFLP assay was used to screen 213 eae-positive E. coli isolates derived from ovine, bovine, and human sources comprising 60 serotypes. Of these, 82 were STEC isolates, 89 were stx-negative (stx(-)) and ehxA-positive (ehxA(+)) isolates, and 42 were stx(-) and ehxA-negative isolates. Int-beta, the most commonly identified eae subtype (82 of 213 [38.5%] isolates), was associated with 21 serotypes, followed by Int-zeta (39 of 213 [18.3%] isolates; 11 serotypes), Int-theta (25 of 213 [11.7%] isolates; 15 serotypes), Int-gamma (19 of 213 [8.9%] isolates; 9 serotypes), and Int-epsilon (21 of 213 [9.9%] isolates; 5 serotypes). Intimin subtypes alpha1, alpha2, kappa, lambda, xi, micro, nu, and iota were infrequently identified; and Int-eta was not detected. Phylogenetic analyses with the Phylip package of programs clustered the intimin subtypes into nine distinct families (alpha, beta-xi, gamma, kappa, epsilon-eta-nu, iota- micro, lambda, theta, and zeta). Our data confirm that ruminants are an important source of serologically and genetically diverse intimin-containing E. coli strains. (+info)
Multiple Ebola virus transmission events and rapid decline of central African wildlife.
(75/548)
Several human and animal Ebola outbreaks have occurred over the past 4 years in Gabon and the Republic of Congo. The human outbreaks consisted of multiple simultaneous epidemics caused by different viral strains, and each epidemic resulted from the handling of a distinct gorilla, chimpanzee, or duiker carcass. These animal populations declined markedly during human Ebola outbreaks, apparently as a result of Ebola infection. Recovered carcasses were infected by a variety of Ebola strains, suggesting that Ebola outbreaks in great apes result from multiple virus introductions from the natural host. Surveillance of animal mortality may help to predict and prevent human Ebola outbreaks. (+info)
Technical note: a procedure for the preparation and quantitative analysis of samples for titanium dioxide.
(76/548)
A procedure was developed for the rapid analysis of titanium dioxide (TiO2) concentrations in feed and fecal samples. Samples were digested in concentrated H2SO4 for 2 h, followed by addition of 30% H2O2, and absorbance was measured at 410 nm. Standards were prepared by spiking blanks with increasing amounts of TiO2, resulting in a linear standard curve. Complete analysis using this procedure can typically be accomplished within 4.5 h. This procedure was compared to a previously published dry-ash procedure for the analysis of TiO2 in bovine fecal samples. Three sources of OM devoid of TiO2 (a forage sample, a bovine fecal sample without Cr2O3, and a bovine fecal sample containing Cr2O3) were spiked with graded amounts (0, 2, 4, 6, 8, or 10 mg) of TiO2. With our procedure, TiO2 recoveries averaged 96.7, 97.5, and 98.5%, for the three OM sources, respectively, vs. 74.3, 83.8, and 53.1% for the same samples analyzed using the dry-ash method. These results suggest that our procedure is a rapid and accurate alternative to dry-ash procedures for the determination of TiO2. (+info)
Steroid hormone modulation of prostaglandin secretion in the ruminant endometrium during the estrous cycle.
(77/548)
Prostaglandins, produced from membrane phospholipids by the action of phospholipase A2, cyclooxygenase, and specific prostaglandin synthases, are important regulators of ovulation, luteolysis, implantation, and parturition in reproductive tissues. Destruction of the corpus luteum at the end of the estrous cycle in nonpregnant animals is brought about by the pulsatile secretion of prostaglandin F(2alpha) (PGF(2alpha)) from the endometrium. It has been known for many years that progesterone, estradiol, and oxytocin are the hormones responsible for luteolysis. To achieve luteolysis, two independent processes have to be coordinated; the first is an increase in the prostaglandin synthetic capability of the endometrium and the second is an increase in oxytocin receptor number. Although progesterone and estradiol can modulate the expression of the enzymes involved in prostaglandin synthesis, the primary reason for the initiation of luteolysis is the increase in oxytocin receptor on the endometrial epithelial cells. Results of many in vivo studies have shown that progesterone and estradiol are required for luteolysis, but it is still not fully understood exactly how these steroid hormones act. The purpose of this article is to review the recent data related to how progesterone and estradiol could regulate (initiate and then turn off) the uterine pulsatile secretion of PGF(2alpha) observed at luteolysis. (+info)
Epigenetics and assisted reproductive technology: a call for investigation.
(78/548)
A surprising set of recent observations suggests a link between assisted reproductive technology (ART) and epigenetic errors--that is, errors involving information other than DNA sequence that is heritable during cell division. An apparent association with ART was found in registries of children with Beckwith-Wiedemann syndrome, Angelman syndrome, and retinoblastoma. Here, we review the epidemiology and molecular biology behind these studies and those of relevant model systems, and we highlight the need for investigation of two major questions: (1) large-scale case-control studies of ART outcomes, including long-term assessment of the incidence of birth defects and cancer, and (2) investigation of the relationship between epigenetic errors in both offspring and parents, the specific methods of ART used, and the underlying infertility diagnoses. In addition, the components of proprietary commercial media used in ART procedures must be fully and publicly disclosed, so that factors such as methionine content can be assessed, given the relationship in animal studies between methionine exposure and epigenetic changes. (+info)
Studies on the regulation of expression of luteinizing hormone receptor in the ovary and the mechanism of follicular cyst formation in ruminants.
(79/548)
In the series of studies, changes of expression and regulation of luteinizing hormone (LH) receptor in the ovary of domestic ruminants were examined. Furthermore, mechanisms of formation of follicular cysts in domestic ruminants, caused by stress and so on, were endocrinologically elucidated. Results of the studies provide the following conclusions. (1) The quantity of LH receptor in the bovine antral follicles increases rapidly in the latter stage of its development. (2) The quantity of LH receptor and its mRNA in the bovine and caprine corpus luteum increase during their developments. The increase of the receptor in the caprine luteal development is regulated by LH through the receptor mRNA level. (3) At least, three splice variants of LH receptor mRNA exist in the bovine luteal tissue and the variant receptors are expressed at different cellular sites according to its structure. (4) Intracellular consecutive cysteine residues of LH receptor are palmitoylated and thereby inhibit internalization of the receptor. (5) As a mechanism of the bovine follicular cyst caused by stress, it is suggested that increased secretions of progesterone and cortisol from the adrenal gland exert inhibitory effects on the hypothalamus and follicle, respectively, and subsequently LH and FSH surges are blocked, then finally ovulation is suppressed and the follicle becomes cystic. (+info)
Brown adipose tissue development and metabolism in ruminants.
(80/548)
We conducted several experiments to better understand the relationship between brown adipose tissue (BAT) metabolism and thermogenesis. In Exp. 1, we examined perirenal (brown) and sternum s.c. adipose tissue in 14 Wagyu x Angus neonates infused with norepinephrine (NE). Perirenal adipocytes contained numerous large mitochondria with well-differentiated cristae; sternum s.c. adipocytes contained a few, small mitochondria, with poorly developed cristae. Lipogenesis from acetate was high in BAT but barely detectable in sternum s.c. adipose tissue. In Exp. 2, we compared perirenal and tailhead adipose tissues between NE-infused Angus (n = 6) and Brahman (n = 7) newborn calves. Brahman BAT contained two-to-three times as many total beta-receptors as Angus BAT. The mitochondrial UCP1:28S rRNA ratio was greater in Brahman BAT than in BAT from Angus calves. Lipogenesis from acetate and glucose again was high, but lipogenesis from palmitate was barely detectable. Tail-head s.c. adipose tissue from both breed types contained adipocytes with distinct brown adipocyte morphology. In Exp. 3, three fetuses of each breed type were taken at 96, 48, 24, 14, and 6 d before expected parturition, and at parturition. Lipogenesis from acetate and glucose in vitro decreased 97% during the last 96 d of gestation in both breed types, whereas the UCP1 gene expression tripled during gestation in both breed types. At birth, palmitate esterification was twice as high in Angus than in Brahman BAT and was at least 100-fold higher than in BAT from NE-infused calves from Exp. 2. Uncoupling protein-1 mRNA was readily detectable in tailhead s.c. adipose tissue in all fetal samples. In Exp. 4, male Brahman and Angus calves (n = 5 to 7 per group) were assigned to 1) newborn treatment (15 h of age), 2) 48 h of warm exposure (22 degrees C) starting at 15 h of age, or 3) 48 h of cold exposure (4 degrees C) starting at 15 h of age. Brahman BAT adipocytes shrank with cold exposure, whereas Angus BAT adipocytes did not. Similarly, BAT from neonatal lambs (Exp. 5; n = 6 per group) was depleted of lipid in response to cold exposure, although UCP1 gene expression persisted. In Exp. 4, NE stimulated lipogenesis from palmitate in BAT incubated in vitro. Lipogenesis from palmitate was higher in Angus than in Brahman BAT, and increased with both warm and cold exposure. These studies suggest that BAT from Brahman calves may be exhausted of lipid shortly after birth during times of cold exposure. (+info)