Effects of iron deficiency and exercise on myoglobin in rats

The effects of iron deficiency and endurance training on muscle myoglobin (Mb), body weights, and blood lactic acid concentration were studied in rats. Fifty animals were divided into four groups: anemic trained (AT), normal trained (NT), anemic sedentary (AS), and normal sedentary (NS). Following 5 weeks of dietary control, the mean hemoglobin values for the AT and AS rats were 0.013 +/- 0.002 mmol X l-1 (8.7 +/- 1.4 g X dl-1) and 0.014 +/- 0.003 mmol X l-1 (9.2 +/- 1.7 g X dl-1) respectively, and did not significantly change throughout the study. AT and NT rats were run on a motor driven treadmill 4 days/week for 6 weeks up to a pre-established time of 90 min. Following the training, body weights of the AT (157 +/- 13 g) and NT (153 +/- 13 g) rats were lower than their respective sedentary groups AS (172 +/- 9 g) and NS (176 +/- 15 g). Resting blood lactic acid concentration following training was lower in both trained groups, AT (3.3 +/- 2.0 mM) and NT (2.3 +/- 1.9 mM) compared to AS (8.2 +/- 2.6 mM) and NS (3.8 +/- 1.6 mM). Training increased Mb concentration in hearts of both the anemic and normal trained groups (AT, 0.66 +/- 0.13 mg X g-1; NT, 0.95 +/- 0.08 mg X g-1) compared to the sedentary groups (AS, 0.44 +/- 0.08 mg X g-1; NS, 0.70 +/- 0.13 mg X g-1). Only the AT rats showed an increase in skeletal muscle Mb. This study provides evidence that myoglobin may limit aerobic metabolism.     

Cell Cycle activation and ouabain-sensitive ion movements of 3T3 and C3H-10T½ fibroblasts

The introduction of either PGF_2α (10^?7 M) or TPA (10^?7 M) stimulated, ouabain-sensitive ⁸⁶Rb⁺ influx at 30 min in postconfluent 3T3-4 mouse fibroblast cultures by 117% and 124%, respectively. Both TPA and PGF_2α at these concentrations stimulated the incorporation of ³H-TdR into DNA. TPA had the greatest stimulatory effect, which was similar to that obtained with 10% fetal calf serum. In accord with the idea that modulation of membrane processes such as Na⁺/K⁺ pump activity in fibroblasts may reflect important events related to the initiation of DNA synthesis, it was observed that in both 3T3-4 and C3H-1 0T½ cells there were parallel increases in ³H-TdR incorporation and ouabain-sensitive ⁸⁶Rb⁺ influxes with 10^?7 M TPA, whereas PGF_2α stimulated a significant increase in ³H-TdR incorporation in 3T3-4 but not C3H-10T½ cells and only marginal increases in ouabain-sensitive ⁸⁶Rb⁺ influx in both. Therefore, although there appears to be a close correlation between Na⁺/K⁺ pump activation and subsequent S-phase entry following TPA stimulation, a similar correlation for PGF_2α cannot be confirmed.     

Genetic variation for aerial dispersal behavior in the Banks grass mite

Banks grass mites, Oligonychus pratensis (Banks), exhibit a behavior that facilitates their dispersal as aerial plankton over long distances. The propensity to display this behavior and its latency varies among individual mites. Some of this variation can be attributed to genetic differences among individuals. Mother-daughter resemblance and bi-directional selection were used to estimate the genetic component of latency of the aerial dispersal behavior in a wild population collected from corn plants. Mother-daughter regression analysis suggested that up to 10% of variation in initiation of aerial dispersal behavior was attributable to an additive genetic component. Subsequent selection for shorter and longer latency resulted in significant divergence between selected lines after 9 generation, but the response was not symmetrical. Realized heritability for shorter latency was 0.09, while that for longer latency was not different from 0. This response to selection was consistent with results of the mother-daughter analysis, and the response asymmetry may explain the high variability in the mother-daughter regression. In both their natural habitat and in a corn agroecosystem, mites survive by using a succession of temporarily available hosts. Aerial dispersal behavior by Banks grass mites facilitates colonization of new hosts. The genetic basis and selection response of behavior initiating aerial dispersal is consistent with its role in mites population dynamics in this setting.     

Characterization of a monoclonal antibody to human proacrosin and its use in acrosomal status evaluation.

Among the monoclonal antibodies (MAb) selected after immunization of mice with a detergent-insoluble fraction from human spermatozoa, MAb 4D4 was found to stain in immunofluorescence the principal part of the acrosome of human spermatozoa. Acrosome reaction induced decreased and spotty 4D4 immunofluorescence staining. Immunoelectron microscopy before or after embedding revealed that the epitope defined by MAb 4D4 was sequestered in the anterior acrosomal matrix and, after the acrosome reaction, remained partly bound on matrix elements attached to the inner acrosomal membrane. Western blot analysis of sperm extracts showed that the epitope defined by MAb 4D4 was located on a 55 KD polypeptide in whole cells and on 55 and 50 KD polypeptides in non-ionic detergent fractions. Human proacrosin-enriched fraction obtained by FPLC purification exhibited several proteolytic activities against gelatin in gel enzymography: a 50 KD major band and two minor bands in the 20-30 KD area; the 50 KD polypeptide reacted with MAb 4D4 in Western blots. Furthermore, the 4D4-immunoprecipitated polypeptide from sperm extract showed that the 50 KD band exhibited proteolytic activity with an optimal pH at 8.0 that was strongly inhibited by soybean trypsin inhibitor and ZnCl2. MAb 4D4 also reacted with the acrosome of the monkey Macaca fascicularis but not with the acrosome of any of the other non-primate mammalian species examined so far. Various shape defects of the acrosomal principal region were revealed by 4D4 labeling of spermatozoa with head anomalies from infertile patients. MAb 4D4 also recognized proacrosin in paraffin-embedded human testis sections. These data make the monoclonal antiproacrosin antibody 4D4 an efficient tool for evaluation of the acrosomal status of human spermatozoa and spermatids.