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51.
52.
At chicken of the race "White Leghorn" the content of nuclei in the kidney was highest (14.60 x 10(9)) on the 203rd, in the spleen on the 112th (14.85 x 10(9)), in the gizzard on the 112th (18,24 x 10(9)) and in the M. pectoralis superficialis on the 168th day (36.42 x 10(9)) after hatching. The biggest fresh weight:DNA-ratio was determined in the kidney on the 203rd (285), in the spleen on the 28th (92) and in the gizzard (694) and in the M. pectoralis superficialis (1984) on the 203rd day. The DNA-concentration on the 2nd day after hatching in the kidney was 4,56 +/- 0,36, in the spleen 11.49 +/- 0.84, in the gizzard 1.85 +/- 0.13 and in the M. pectoralis superficialis 2.96 +/- 0.18 mg/g wet weight respectively the RNA:DNA-ratio in these tissues 1.00, 0.88, 1.70 and 0.85. The growth of tissues by the increase of the number of cells (hyperplasia) and of the volume of cells (hypertrophy) is described. 相似文献
53.
Northern red oak (Quercus rubra L.) and yellow-poplar (Liriodendron tulipifera L.) were grown for two years in full sunlight (unshaded) or 20% of full sunlight (shaded) under either well-watered or drought conditions. There was a close association between evaporative flux (in situ) and leaf-specific conductivity (LSC) in stem segments of both species. Shaded, drought-stressed seedlings of both species had significantly reduced leaf area, evaporative flux, volume flow rate in xylem, flow velocity, potentially functional xylem area, and LSC than unshaded, well-watered seedlings. Reductions in LSC associated with drought or shade were similar for both species; and within a treatment, both species had similar LSC. Species differed in the manner of LSC adjustment to drought and shade. Reductions in leaf area associated with drought or shade were accompanied primarily by reductions in potentially functional xylem area for L. tulipifera, and by reductions in flow velocity for Q. rubra. These results suggest (1) the existence of a homeostatic balance between evaporative flux and LSC, (2) that species with widely different growth patterns and xylem anatomies may develop similar LSC within the same environment, and (3) a possible hydraulic basis for differences in habitat between ring- and diffuse-porous species. 相似文献
54.
We investigated leaf gas exchange responses to leaf temperature, leaf-to-air vapor pressure deficit (VPD), and predawn and midday shoot water potential (psipd and psimd, respectively) of two native Sonoran Desert riparian tree species, Fremont cottonwood (Populus fremontii S. Wats.) and Goodding willow (Salix gooddingii Ball), and one exotic riparian tree species, saltcedar (Tamarix chinensis Lour. and related species). Measurements were made at two sites over 2 years that differed climatically. Because multiple linear regression models explained less than 29% of the variation in stomatal conductance (gs) and less than 48% of the variation in net photosynthetic rate (Pn) of all species, we used boundary-line analysis to compare gas exchange responses among species. Gas exchange rates were high in all species. The hyperbolic relationship between Pn and gs suggested that initial reductions in gs at high gs did not inhibit Pn. Reductions in gs of cottonwood and willow occurred at psimd values at or below previously reported xylem cavitation thresholds (-1.6 and -1.4 MPa, respectively), indicating tight stomatal regulation of water loss and a narrow cavitation safety margin. In contrast, reductions in gs of saltcedar occurred at psimd values well above the cavitation threshold (-7.0 MPa), but at much lower psimd values than in cottonwood and willow, suggesting a wider cavitation safety margin and less tight regulation of water loss in saltcedar. High VPD had a smaller effect on leaf gas exchange in willow than in cottonwood. In contrast, willow had a less negative psipd threshold for stomatal closure than cottonwood. Compared with cottonwood and willow, leaf gas exchange of saltcedar was more tolerant of high VPD and low psipd. These physiological characteristics of saltcedar explain its widespread success as an invader of riparian ecosystems containing native Fremont cottonwood and Goodding willow in the Sonoran Desert. 相似文献
55.
To assess the influence of stream water on leaf gas exchange and water potential in different sized boxelder trees (Acer negundo L.), we compared these characteristics in trees growing beside a perennial stream and a nearby ephemeral stream in a montane-riparian forest in northern Arizona. Patterns of tree water use were quantified by stable isotope analysis (delta(18)O). Physiological characteristics were similar for large and small trees. Similarity between sites in predawn and daytime water potentials and xylem delta(18)O indicated that stream water was not a physiologically important water source. Seasonal and site variations in light-saturated net photosynthetic rate were significantly related to leaf-to-air vapor pressure deficit (r = -0.691) and foliar nitrogen concentration (r = 0.388). Although deep water was the dominant water source, surface soil water was utilized following precipitation, especially by small trees. We conclude that net carbon gain and severity of water stress are only weakly coupled to stream water availability. 相似文献
56.
H Ülker M Küçük A Ylmaz M Yörük L Arslan DM deAvila JJ Reeves 《Reproduction in domestic animals》2009,44(1):37-43
This study was designed to evaluate the effectiveness of recombinant Ovalbumin-LHRL (OL) immunization on changes in testicular size, histological appearance and testosterone production in buck kids. Thirty native buck kids at 18 weeks of age were divided into three groups, control (n = 10), immunization (n = 10) and castration (n = 10) groups. Immunized animals received OL protein generated by recombinant DNA technology. Ultrasonographic and histological examinations of the testes were performed. Animals were slaughtered at 44 weeks of age. Semen and epididymides were evaluated for the presence of sperm cells. Immunized animals generated anti-LHRH antibodies. Testosterone production, testicular and accessory glands development and sperm production were suppressed in the immunized animals (p < 0.01). Semineferous tubule diameters decreased (p < 0.01), basal membrane of the tubule was thickened and hyalinized in immunized kids. Immunization affected ultrasonographic appearance of the testes drastically. While testes of control animals gained their normal ultrasonographic appearance as the age increased, immunized animals had uniform hypoechogenic testicular structure as observed at 18 weeks of age until slaughter. Simultaneous histological and ultrasonographic evaluations indicated that the changes in testicular histology could partly be monitored via ultrasonographic imaging; nevertheless, it is difficult to claim that ultrasonographic image reflects the exact changes in such instances. In conclusion, these results indicate that recombinant OL fusion protein is effective in immunocastration in buck kids and has a potential to be used as an alternative to physical castration. Further researches should be conducted to help assessing reproductive status of testes from ultrasound images. 相似文献
57.
GW Smith MP Gerard NB Campbell DM Foster SM Smith JL Davis 《Australian veterinary journal》2009,87(12):487-491
Objective To develop a simple and effective surgical technique for third‐compartment cannulation in alpacas. Design Prospective study using six adult male alpacas. Methods General anaesthesia was induced and a polyurethane gastrostomy tube was surgically implanted into the distal portion of the third compartment. Results Three of the alpacas retained their cannulas for a 100‐day period; however, three cannulas were dislodged during the study. Two of the three dislodged cannulas were replaced during a second surgical procedure. Cannulas were well tolerated by the alpacas and all animals remained clinically healthy during the study period. Third compartment contents did not leak from the cannulation site. The tubes were manually removed following the completion of the study and the small defect in the body wall quickly healed over in all animals. Conclusion Surgical placement of polyurethane tubes designed for percutaneous endoscopic gastrostomy is a useful method of cannulating the third compartment in camelids. This technique can be used for experimental studies and possibly could be used for nutritional support and fluid therapy in sick camelids that might need long‐term care. 相似文献
58.
Congenital dyserythropoietic anaemia (CDA) is a heterogeneous group of rare genetic disorders that in humans is characterised by ineffective haematopoiesis with morphological abnormalities in erythroid precursor cells and secondary iron overload. In the 1990s, a syndrome of CDA with dyskeratosis and progressive alopecia was reported in Poll Hereford calves in Canada and the USA. We report the clinical and pathological findings in two Poll Hereford calves with this syndrome from separate properties in South Australia. The animals had a variably severe anaemia, associated with abnormal nucleated red blood cells in peripheral blood, and large numbers of rubricytes and metarubricytes with a characteristic nuclear ultrastructure in the bone marrow. Both calves were born with a wiry hair coat and a progressively ‘dirty‐faced’ appearance associated with hyperkeratosis and dyskeratosis (apoptosis). 相似文献
59.
E Kolb B Beyer K V Brenner E Grün G Gründel C Schineff U Schmidt M Stirn 《Archiv fuer experimentelle veterinaermedizin》1979,33(2):207-224
The crude protein levels as well as the activities of various enzymes were studied in certain tissues of fetuses (80th through 114th days of development), piglets of different age groups, and pigs for slaughter. In most of the tissues tested the postnatal activities of Na-K-ATPase were beyond those recorded from fetuses. The highest GOT activities were recorded from the liver, myocardium, and kidneys. Activities were found to rise sizeably in some tissues after birth. The activity of GPT, too, exhibited age-dependent variations. The activity of leucine-aminopeptidase increased strongly after birth in liver and kidneys. Acid phosphatase activity was less markedly influenced by development phases. Those enzymes which are involved in the formation of fructose and glucose (aldolreductase, glucuronate-reductase, and sorbite-dehydrogenase) had their highest activities, all age-dependent, in liver and kidneys. 相似文献
60.