Urea formation in kidneys of the domestic fowl in early postincubation ontogenesis]

The nitrogen secretion is not limited in any animal species to one final nitrogenous metabolite only. In the organism of uricotelic birds, besides other products, urea is produced. It was revealed that it developed also in the kidney of the domestic fowl. In the experiments with 130 cockerels of the White Leghorn breed--a commercial Primant hybrid at the age from 0 to 62 days--we determined the urea concentration in the supernatant of kidney homogenate and in the heparinized blood plasma by diacetylmonoxim according to Homolka (1971). In the kidney we observed a moderate insignificant increase of urea concentration from 0 to 62 days of post-incubation life (zero-day: 34.77 +/- 9.20 mg per 100 g; the 62nd day: 36.46 +/- 14.66 mg per 100 g). In the heparinized blood plasma the urea concentration was increased significantly from the initial values of 16.66 +/- 3.17 mg per 100 ml (zero-day) to 54.03 +/- 3.19 mg per 100 ml (the 62nd day).     

Toxicological and mechanistic studies on neonicotinoid cross resistance in Q-type Bemisia tabaci (Hemiptera: Aleyrodidae)

The tobacco whitefly, Bemisia tabaci Gennadius (Homoptera: Aleyrodidae) is a serious pest in numerous cropping systems and has developed a high degree of resistance against several chemical classes of insecticides. One of the latest group of insecticides introduced to the market were the neonicotinoids (chloronicotinyls), acting agonistically on insect nicotinic acetylcholine receptors. Resistance to neonicotinoid insecticides has recently been shown to occur, especially in Q-type B tabaci in some places in Almeria, Spain, whereas control of B-type B tabaci in many other intense cropping systems worldwide has remained on high levels. Our study revealed that neonicotinoid-resistant Q-type strains from Almeria were often more than 100-fold less susceptible to thiamethoxam, acetamiprid and imidacloprid when tested in discontinuous systemic laboratory bioassays. The resistance factors were generally 2- to 3-fold lower in leaf-dip bioassays. In addition to the Spanish strains, we obtained two other highly neonicotinoid-cross-resistant B tabaci greenhouse populations, one from Italy (December 1999) and one from Germany (June 2001). A molecular diagnostic analysis revealed that both strains also belong to the (Spanish) subtype Q of the B tabaci species complex. The resistance levels of Q-type whitefly strains derived from Almeria greenhouses in 1999 remained stable for at least two years, even when maintained in the laboratory without any selection pressure. The biochemical mechanisms conferring resistance to neonicotinoids have not yet been elucidated in detail, but synergist studies suggested a possible involvement of microsomal monooxygenases. Furthermore, we checked two Almerian strains of B tabaci isolated in 1998 and 1999 and demonstrated that neonicotinoid resistance is not due to an altered [3H]imidacloprid binding site of nicotinic acetylcholine receptors.     

Influence of growth rate and exposure to bulls on age at puberty in beef heifers

Two experiments were conducted to test the following hypotheses: 1) exposure of beef heifers to sterile bulls increases the proportion of heifers attaining puberty by 14 mo of age and 2) rate of growth interacts with bull exposure to influence age at puberty in beef heifers. In Exp. I, heifers were assigned to one of two treatments: 1) heifers were exposed to bulls (BE; approximately 70-d period of exposure) or 2) heifers were isolated from bulls (NE) and served as controls. In Exp. II, heifers were assigned to either BE or NE treatments (175-d period of exposure to bulls) and were fed to gain at a moderate (MG; .6 kg/d) or high (HG; .8 kg/d) growth rate. Blood samples were collected twice weekly to determine concentrations of progesterone indicative of onset of corpus luteum function and puberty. In Exp. I a greater (P less than .05) proportion of heifers receiving the BE treatment than of heifers receiving the NE treatment initiated corpus luteum function by 14 mo of age. In Exp. II, there was a bull exposure x growth rate interaction (P less than .05). The effect of bull exposure was greater within the HG groups than within the MG groups. However, heifers fed to attain a moderate or high growth rate and exposed to bulls attained puberty at younger ages than heifers not exposed to bulls and fed to attain a moderate or high growth rate. Mean ages at puberty were 375, 422, 428, and 449 (pooled SEM = 8.6) d for heifers in the BE-HG, BE-MG, NE-HG, and NE-MG groups, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)     

Isolation and characterization of bone marrow-derived equine mesenchymal stem cells

OBJECTIVE: To isolate and characterize bone marrow-derived equine mesenchymal stem cells (MSCs) for possible future therapeutic applications in horses. SAMPLE POPULATION: Equine MSCs were isolated from bone marrow aspirates obtained from the sternum of 30 donor horses. PROCEDURES: Cells were cultured in medium (alpha-minimum essential medium) with a fetal calf serum content of 20%. Equine MSC features were analyzed to determine selfrenewing and differentiation capacity. For potential therapeutic applications, the migratory potential of equine MSCs was determined. An adenoviral vector was used to determine the transduction rate of equine MSCs. RESULTS: Equine MSCs can be culture-expanded. Equine MSCs undergo cryopreservation in liquid nitrogen without altering morphologic characteristics. Furthermore, equine MSCs maintain their ability to proliferate and differentiate after thawing. Immunocytochemically, the expression of the stem cell marker CD90 can be detected on equine MSCs. The multilineage differentiation potential of equine MSCs was revealed by their ability to undergo adipogenic, osteogenic, and chondrogenic differentiation. CONCLUSIONS AND CLINICAL RELEVANCE: Our data indicate that bone marrow-derived stromal cells of horses can be characterized as MSCs. Equine MSCs have a high transduction rate and migratory potential and adapt to scaffold material in culture. As an autologous cell population, equine MSCs can be regarded as a promising cell population for tissue engineering in lesions of the musculoskeletal system in horses.     

Influence of the acetification process on phenolic compounds

Little is known about the change of phenolic compounds and total phenolic content by the acetification process. The aim of this study was to assess the contents of selected phenolic compounds of cider and red and white wines in comparison to phenolic profiles in corresponding vinegars by using a new HPLC method for the simultaneous separation and quantification of polar phenolic acids and less polar flavonoids. Identifications were made by retention times and by means of mass spectra. Additionally, total phenolic contents of wines and vinegars were determined photometrically. The decrease in total phenol content by the acetification process was highest for cider vinegars (40%) and lower for red and white wine vinegars (13 and 8%, respectively). A decrease in the contents of individual phenolic compounds of vinegars from white white and ciders was not observed. In contrast, the contents of individual phenolic compounds in red wine vinegar decreased approximately 50%.     

Estradiol-concentrating neurons: topography in the hypothalamus by dry-mount autoradiography

Serial section autoradiograms were prepared of different planes of the hypothalamus and diencephalon of immature female, immature male, and ovariectomized mature rats injected with 6,7-(3)H-estradiol-17 beta. Known causes of diffusion and redistribution of the label, such as fixation, embedding, and thawing, were eliminated by the use of an autoradiographic technique based on the dry-mounting of freeze-dried sections. Neurons that concentrate estradiol exist in distinct and definable anatomical areas that are independent of the sex and hormonal state of the animals. Distribution of these neurons follows known terminations of the stria terminalis, which supports the concept of an endocrine amygdaloid-hypothalamic-hypophysial axis.     

Feedback of 17 beta-estradiol on secretion of luteinizing hormone during different seasons of the year

The working hypothesis was that the amount of increase in secretion of luteinizing hormone (LH) that results from positive feedback of 17 beta-estradiol (E2) is dependent on season of the year in mature bovine females. Seven beef cows, ovariectomized approximately 2 mo before the initiation of the experiment, were used in the initial year (1983) of the study. Three of the ovariectomized cows (OVX-E2) received an sc E2 implant, which provided low circulating levels of E2. The remaining four cows (OVX) were not implanted. Blood samples were collected serially (at 10-min intervals for 6 h) at each spring and fall equinox and at each summer and winter solstice. This protocol was replicated with a different group of cows in 1985 (OVX-E2, n = 4; OVX, n = 6). Concentration of LH in blood serum was quantified in all samples. Concentration of E2 in blood serum was measured in pools of samples from each serial blood collection. Concentrations of E2 were higher (P less than .05) in the implanted cows. Mean concentration of LH and amplitude of pulses of LH were higher (P less than .05) at each season of the year in cows that were ovariectomized and implanted with E2 than in cows that were ovariectomized and did not receive E2. An effect of season of the year on mean concentration of LH was detected (P less than .01). No influence of season or E2 was detected for frequency of pulses of LH. There was no significant treatment X season interaction.(ABSTRACT TRUNCATED AT 250 WORDS)