Intact Populations Research Articles

Natriuretic effect of atriopeptin III in rats with papillary necrosis

This study compared the effects of atriopeptin III (AP III) on sodium excretion and renal interstitial hydrostatic pressure (RIHP) in control rats and in rats pretreated with 2-bromoethylamine (BEA) to produce papillary necrosis. In control rats, infusion of AP III (100 ng.kg-1.min-1) increased sodium excretion from 2.2 +/- 0.7 to 6.4 +/- 0.9 microeq.min-1.g kidney wt-1 and RIHP from 6.8 +/- 0.7 to 8.7 +/- 0.9 mmHg, whereas glomerular filtration rate and renal blood flow were unaltered. Similar results were obtained in rats pretreated with BEA 48 h before the experiment. In rats studied 6 wk after BEA treatment, the papilla was absent and there was atrophy of juxtamedullary nephrons. AP III did not alter sodium excretion or RIHP in this group of rats. These results indicate that 1) an intact renal papilla and/or juxtamedullary nephron population may be required for the natriuretic effect of AP III; 2) the papillary injury 48 h after BEA is not sufficient to abolish the natriuretic response to AP III; and 3) elevations in RIHP may play a role in the natriuretic response to AP III.

Role of cells sensitive to anti-mouse brain serum in the regulation of CFU-S proliferation

CFU-S differentiation and regeneration kinetics in the spleen and femur was studied after treatment of bone marrow cells with RAMB serum. The effect of thymocytes on the rate of CFU-S regeneration was also investigated. It was found that CFU-S regeneration in the spleen was similar in RAMBS-treated and intact cell populations on days 4-14 after transplantation. On the contrary, the rate of CFU-S regeneration in the femur was slower in RAMBS-treated than in intact bone marrow cells. However, the growth rate in the femur could be restored to the normal level by the administration of freshly isolated syngeneic thymocytes to mice pre-injected with RAMBS-treated CFU-S population. The treatment of bone marrow suspension with RAMB serum did not affect the differentiation of spleen colonies. It is suggested that RAMBS eliminates cell population regulating CFU-S proliferation, without affecting its differentiation.

Comparison of methods for measuring production by the submersed macrophyte, Potamogeton perfoliatus L.1,2

Six conventional methods for measuring primary production of submersed vascular plants were compared to test for previously suggested inherent shortcomings in the O2‐exchange techniques. Production was measured for experimental populations of Potamogeton perfoliatus L., from upper Chesapeake Bay in five comparative studies, each including an O2‐exchange method. All techniques tested (14C incorporation and O2 evolution for both bottle incubations and undisturbed populations; biomass accumulation and inorganic carbon consumption for intact populations) compared favorably, with mean (molar) ratios of oxygen to carbon production ranging from 0.9 to 1.6. In addition, direct measurements indicated that rhizosphere release of O2 would introduce only small errors (<5%) in O2 production estimates. Although changes in lacunal storage of O2 can result in brief (5–25 min) delays between O2 production and evolution to the external water, simple methodological precautions can overcome such problems. We conclude that all available methods for measuring productivity of this and related species are potentially useful, each having its particular strengths and weaknesses, and the use of more than one method is recommended.

Optimal design of nature reserves: Consequences of genetic drift

Computer simulations were used to compare rates of genetic drift and allele fixation in intact populations with those in subdivided populations with the same total numbers of individuals. Subdivided populations with occasional inter-subpopulation migrations typically preserve more heterozygotes over the long term and preserve allelles longer than do corresponding intact populations. Intact populations typically exhibit a short-term (50 generations) advantage over subdivided populations in maintaining heterozygosity. Rates of genetic drift are influenced by population size, intersubpopulation migration rate, and degree of population subdivision. Archipelagos of refuges with occasional inter-refuge migration appear to be the optimal design strategy for genetic conservation.

Long-term marrow culture reveals chromosomally normal hematopoietic progenitor cells in patients with Philadelphia chromosome-positive chronic myelogenous leukemia.

We found that when marrow cells from four patients with newly diagnosed Philadelphia chromosome-positive chronic myelogenous leukemia were maintained in culture for two to four weeks, a previously undetectable population of chromosomally normal hematopoietic cells (including erythroid, granulopoietic, and pluripotent progenitors) became readily demonstrable in three cases. Time-course studies showed that in such cultures the dominant Philadelphia chromosome-positive population rapidly disappeared, in contrast to coexisting chromosomally normal progenitors, which remained detectable for periods of two to three months. Long-term marrow cultures thus offer a new approach to the assessment of a suppressed but functionally intact population of chromosomally normal hematopoietic stem cells in patients with chronic myelogenous leukemia.

Cell-mediated immunity in chronically diabetic mice.

A radioisotopic ear assay for delayed hypersensitivity (DH) to 2,4-dinitrofluorobenzene (DNFB) was used to investigate cellular immune function in chronic alloxan- diabetic C57BI/6 mice. The specific migration of 5-(125I)Iodo-2'-deoxyuridine-labeled monocytes to the site of antigenic challenge was employed to quantitatively measure the OH response. Although both normal and diabetic sensitized mice had a significantly greater DH response than nonsensitized controls, the response of diabetic mice was severely attenuated (23% of normal) The effect of the delayed hypersensitivity response on spleen size was also investigated. In the nonsensitized state the spleens of diabetic mice were approximately 30% smaller than the spleens of normal mice. After sensitization with DNFB, and up to the time of antigenic challenge, the spleens from both diabetic and normal mice increased 2.1-fold in weight. After challenge, however, the diabetic spleen maintained its prechallenged size while the normal spleen increased an additional 30% in weight. When either sensitized normal or diabetic spleen cells were passively transferred to nonsensitized normal recipient mice, a significant DH response was evoked after challenge with DNFB. This response was of equal magnitude after transfer of either the sensitized diabetic or normal spleen cells. The DH response after the passive transfer of spleencells from either normal or diabetic sensitized donors to diabetic recipients was very markedly attenuated and in fact questionably significant when compared with the nonspecific inflammatory response to DNFB. These results indicate that an intact population of DNFB-sensitized cells exists in the diabetic, but that an inhibition of T-lymphocyte or monocyte activity is occurring during the secondary challenge. The chronic hypoinsulinemia, hyperglycemia, and catabolic metabolism of the alloxan-diabetic mouse does not qualitatively alter the immune cellular processes associated with primary sensitization but significantly attenuates the secondary response.

Dissociation of blastogenic factor production and lymphocyte transformation of guinea pig lymphocytes stimulated with tuberculin PPD.

In vitro lymphocyte transformation of guinea pig lymph node cells induced by tuberculin PPD was essentially eliminated by treatment with 5-bromo-2-deoxyuridine and light. The remaining cell population was still capable of producing blastogenic factor and further, the amount of blastogenic factor released was comparable to that from the intact population in the same interval of culture. This result favors the conception that cells producing blastogenic factor in response to antigen are distinct from the cells responding to the antigen by DNA synthesis and proliferation.

Regeneration of Transplanted Intact Cell Populations in Lethally Irradiated Hydra

A single irradiation of the hydra Pelmatohydra robusta with 0.4 to 10 kR of x rays induced no lethal effects at all, while animals exposed to 40 kR ceased to produce a bud within 24 hr and died within a limited period of time, varying from 10 to 14 days at 25$sup 0$C, and from 28 to 50 days at 10$sup 0$C. This lethal dose of x rays inhibited the proliferation of the cells completely and destroyed interstitial cells. When a small cell mass, which was too small to regenerate alone, was transplanted from the subhypostomal region of an intact animal into the subhypostomal region of the irradiated hydra, the recipient began to produce buds by the proliferation of the graft cells. However, the transplantation of intact peduncle tissue, in which mitotic figures and interstitial cells rarely occurred, failed to produce new buds. (auth)

Heritability of Body Weight and Conformation Traits and Their Genetic Association in Turkeys

Heritabilities were estimated in a strain of Broad Breasted Bronze turkeys for body weight at 8 and 14 weeks of age and body weight, keel length, breast width, body depth and shank length at 21 weeks of age for females and 26 weeks of age for males. Similarly, genetic, environmental and phenotypic correlations were calculated among the seven traits. The strain of turkeys used represented a minimally inbred, intact population selected primarily for reproductive performance. The generation means for the traits in question did not change significantly during the five-year study period.The heritability of body weight varied from 0.31 to 0.41 for male progeny and 0.20 to 0.39 for female progeny. The age at which body weight was taken did not materially affect the size of the heritabilities. Keel length had a heritability of 0.27 to 0.29, breast width 0.19 to 0.32, body depth 0.32 to 0.33 and shank length 0.39 to 0.48 for males and females, respectively.All genetic and phenotypic correlations among the seven traits were positive. All of the phenotypic correlations were statistically significant. Since the genetic correlations were as large or larger than the phenotypic correlations, they too were considered real. The environmental correlations were generally smaller than the genetic correlations with some approaching zero. No obvious genetic antagonisms among these seven traits were noted in this population.