Regulation of beta-endorphin and ACTH in brain by estradiol

The effect of estradiol on the brain concentration of immunoreactive beta-endorphin (beta-EP) and C-terminal ACTH (CLIP) was studied in ovariectomized rats. Dopamine, a known inhibitor of pituitary intermediate lobe pro-opiomelanocortin (POMC), was examined as a possible mediator of the estradiol induced changes in brain POMC. Animals were treated for 1 or 3 weeks with either 1) saline; 2) silastic estradiol implants; or 3) estradiol implants plus haloperidol 1 mg/kg/day. After one week of treatment no significant change in hypothalamic beta-EP content was noted in any group compared to the control level of 4.13 +/- .33 (SEM) pmoles although in the neurointermediate lobe beta-EP increased from 566 +/- 72 to 942 +/- 73 pmoles after haloperidol (p less than .005). After 3 weeks, however, hypothalamic beta-EP decreased from 3.96 +/- .28 to 2.74 +/- .19 pmoles (p less than .005) and C-terminal ACTH decreased from 3.78 +/- .33 to 2.82 +/- .18 pmoles (p less than .02) in the estradiol treated rats. This estradiol induced decrease in the hypothalamic content of beta-EP and C-terminal ACTH was not blocked by haloperidol. We conclude that estradiol lowers the hypothalamic content of beta-EP and CLIP and that this effect does not appear to be mediated by dopamine.     

Changes in quality of stallion spermatozoa during cryopreservation: Plasma membrane integrity and motion characteristics

Better procedures for freezing and thawing equine sperm are needed since variable fertility is obtained when cryopreserved sperm are used. To evaluate current methods of freezing equine sperm, we examined spermatozoal quality by means of two new techniques. These measured the integrity of plasma-acrosomal membranes by immunofluorescent analyses of binding of an antibody specific to the acrosome and evaluated eight parameters of spermatozoal motion using a fully automated computerized system. Five ejaculates from each of eight stallions were processed for freezing in egg yolk-lactose extender with 4% glycerol. Spermatozoal quality was assessed at four different points: at less than 15 min after collecting and before processing (Step 1); after centrifugation and just before freezing (Step 2); immediately after thawing less than 3 h after freezing (Step 3); and immediately after thawing 10 to 20 d after freezing (Step 4). Acrosome-specific monoclonal antibody detected differences (P <0.05) among steps and ejaculates within stallions. All parameters of spermatozoal motion, including the percentage of motile sperm, percentage of progressively motile sperm, curvilinear velocity, straight line velocity, linearity, amplitude of lateral head displacement, and radius of the average path for circularly swimming sperm, differed (P <0.05) among steps, and most of these parameters differed among ejaculates within a stallion and among stallions. For Steps 2 and 3, 62 and 37% of the sperm were motile, and 56 and 23% of all motile sperm had a curvilinear velocity of >100 mum/sec. Most damage to sperm occurred as a result of freezing-thawing, whereas centrifugation of sperm caused only minor damage.     

Restriction fragment polymorphisms as probes for plant diversity and their development as tools for applied plant breeding

Summary Maize and tomato cDNA clones have been hybridized in Southern blotting experiments to plant genomic DNA prepared from different lines to detect restriction fragment polymorphisms (RFPs). In maize we have found that a high degree of genetic variability is present, even among domestic inbred lines. Most randomly chosen maize cDNA clones can be used to detect elements of this variability. Similar levels of polymorphism are observed when genomic DNA is digested with any of a number of different restriction enzymes and probed with individual clones. When a clone is hybridized to genomic DNAs prepared from several different maize lines, a number of different alleles are often detected at a single locus. At the same time one clone can often detect more than one independently segregating locus by cross hybridization to related sequences at other loci. As expected these markers are inherited as simple codominant Mendelian alleles from one generation to the next and colinkage of these markers can be demonstrated in the progeny from a heterozygous parent. In similar studies with tomato, remarkably different results were found. Few RFPs were demonstrable among domestic Lycopersicon esculentum lines although a higher level of variability could be detected when comparing esculentum with its wild Lycopersicon relatives. These results are discussed in relation to the applied uses of RFPs in plant breeding as well as the inherent variability of different plant genomes.This work was supported in part by funds from Sandoz Ltd. (Basel, Switzerland) and its subsidiary company, Northrup King Co. (Minneapolis, Minn., U.S.A.) as well as by NSF SBIR grant #BSR-8360870.     

Regulation of end-expiratory lung volume during sleep in premature infants

To investigate the regulation of end-expiratory lung volume (EEV) in premature infants, we recorded airflow, tidal volume, diaphragm electromyogram (EMG), and chest wall displacement during sleep. In quiet sleep, EEV during breathing was 10.8 +/- 3.6 (SD) ml greater than the minimum volume reached during unobstructed apneas. In active sleep, no decrease in EEV was observed during 28 of 35 unobstructed apneas. Breaths during quiet sleep had a variable extent of expiratory airflow retardation (braking), and inspiratory interruption occurred at substantial expiratory flow rates. During active sleep, the expiratory flow-volume curve was nearly linear, proceeding nearly to the volume axis at zero flow, and diaphragm EMG activity terminated near the peak of mechanical inspiration. Expiratory duration (TE) and inspiratory duration (TI) were significantly shortened in quiet sleep vs. active sleep although tidal volume was not significantly different. In quiet sleep, diaphragmatic braking activity and shortened TE combined to maintain EEV during breathing substantially above relaxation volume. In active sleep, reduced expiratory braking and prolongation of TE resulted in an EEV that was close to relaxation volume. We conclude that breathing strategy to regulate EEV in premature infants appears to be strongly influenced by sleep state.     

Changes in the Microflora of Irradiated Petrale Sole (Eopsetta jordani) Fillets Stored Aerobically at 0.5 C

The microfloral changes on irradiated petrale sole fillets during aerobic (packaged with oxygen-permeable film), refrigerated storage were determined by the identification of bacterial and yeast isolates to the generic level. The samples were irradiated at 0.0, 0.1, 0.15, 0.2, 0.3, and 0.4 Mrad by use of a cobalt-60 gamma source, were stored at 0.5 C, and were examined periodically for spoilage, total microbial population, and composition. The preirradiation flora of the fresh fillets consisted of coryneforms, Achromobacter, Micrococcus, Flavobacterium, Pseudomonas, and Lactobacillus. Immediately after irradiation, Micrococcus, Achromobacter, coryneforms, and Bacillus were predominant. The flora of the nonirradiated fillets at the time of spoilage consisted of Pseudomonas and Achromobacter. The flora of the irradiated fillets at the time of spoilage consisted of Achromobacter and Trichosporon.     

Diversity,equity, and inclusion in the melanoma research community

The inaugural Diversity and Inclusion in Science Session was held during the 2021 Society for Melanoma Research (SMR) congress. The goal of the session was to discuss diversity, equity, and inclusion in the melanoma research community and strategies to promote the advancement of underrepresented melanoma researchers. An international survey was conducted to assess the diversity, equity, and inclusion (DEI) climate among researchers and clinicians within the Society for Melanoma Research (SMR). The findings suggest there are feelings and experiences of inequity, bias, and harassment within the melanoma community that correlate with one's gender, ethnic/racial group, and/or geographic location. Notably, significant reports of inequity in opportunity, discrimination, and sexual harassment demonstrate there is much work remaining to ensure all scientists in our community experience an academic workplace culture built on mutual respect, fair access, inclusion, and equitable opportunity.     

Platelet aggregation and sphingomyelinase D activity of a purified toxin from the venom of loxosceles reclusa

A facile and quantitative assay for measuring the activity of sphingomyelinase D in recluse spider venom has been developed using L-α-[palmitoyl-1-¹⁴C]lysophosphatidylcholine as substrate. This assay avoids the problem of substrate insolubility that occurs when sphingomyelin and other lipids are used as subtrates. This assay has been employed in gel filtration and isoelectric focusing isolation techniques to purify sphingomyelinase D from spider venom. The purified sphingomyelinase exhibits four active enzyme forms in isoelectric focusing with pI values of 8.7, 8.4., 8.2, and 7.8. Each active form when examined in SDS-polyacrylamide gel electrophoresis gave an estimated molecular weight of 32 000. The four active enzyme forms were immunologically cross-reactive with each other as demonstrated with radioimmune assays using an antiserum developed to one of the active forms. Each active form hydrolysed sphingomyelin to release choline and produce N-acylsphingosine phosphate. One of the active enzyme forms was characterized further in dermonecrosis and platelet aggregation measurements. This purified sphingomyelinase D was identified as a poisonous toxin that can develop the typical dermonecrotic spider lesion when injected into experimental animals at levels expected to be delivered in a normal bite. Furthermore, the purified toxin acts to aggregate human blood platelets. The toxin-induced platelet aggregation has been related to serotonin release as aggregation occurs, and it has been shown to be inhibited by EDTA over the range of 0.6 to 3.0 mM EDTA. It is suggested that spider-induced dermonecrosis could result in part from platelet aggregation at and near the site of envenomation.