Pituitary cyclic AMP and plasma hormone responses to epinephrine administration in vivo

The present study was conducted to characterize the in vivo effects of epinephrine administration on levels of pituitary cyclic AMP and plasma hormones. Rats were injected with saline or epinephrine bitartrate (1 mg/kg lP) and sacrificed by decapitation 1, 5, 15, 30 or 60 min post-injection. Levels of pituitary cyclic AMP and plasma ACTH, beta-endorphin, beta-LPH, corticosterone and prolactin were determined by radioimmunoassays. The injection procedure itself was somewhat stressful as demonstrated by increased levels of plasma prolactin and ACTH 5 min following either saline or epinephrine injection. This "stress" response was rapid and short-lasting for the pituitary hormones. The response of the adrenal hormone, corticosterone, to saline injection was slower in onset and longer in duration. Pituitary cyclic AMP levels did not increase following saline injection. Epinephrine-injected animals displayed markedly elevated plasma levels of ACTH, beta-endorphin and beta-LPH at 15, 30 and 60 min as compared to control or saline-injected rats. In addition, levels of pituitary cyclic AMP were increased over 10 fold at these times. Levels of plasma prolactin, a stress-responsive hormone, were not significantly increased in epinephrine-injected animals as compared to saline-injected rats indicating that these later responses seem to be specific to epinephrine rather than to stress.     

Adrenalectomy abolishes the stress-induced increase in pituitary cyclic AMP

We have previously demonstrated that various stressors increase pituitary cyclic AMP in vivo in the rat. In the course of studying the mechanisms mediating this response, we examined the effect of bilateral adrenalectomy on footshock-induced increases in pituitary cyclic AMP. In unoperated rats, intermittent footshock markedly increased pituitary levels of cyclic AMP and plasma levels of corticosterone and prolactin. Adrenalectomy completely abolished the stress-induced increase in pituitary cyclic AMP. The marked increase in plasma prolactin following footshock was not affected by adrenalectomy. Our results indicate that adrenal factors are involved in the stress-induced increase in pituitary cyclic AMP.     

Interspecific variations in the surface ultrastructure of the gills of freshwater mullets

SEM studies were made on the gills of freshwater mullets,Rhinomugil corsula andSicamugil cascasia, to correlate surface ultrastructure of various gill units with their probable functions. Two types of lamellated gill rakers of the former fish are suited for plankton feeding and the short, stumpy and transversely beaded gill rakers of the latter reflect the varied food and feeding habit of the fish.R. corsula has numerous mucous glands on the epithelium covering the gill arch and gill filaments,S. cascasia has fewer. In accordance with the differences in the density and distribution of the mucous glands, the microridged epithelial cells also show variations in their architectural plan. In both species the epithelium of the secondary lamellae is smooth, probably an adaptation for better gaseous exchange.     

Involvement of thyroid gland in the development of migratory disposition in the redheaded bunting, Emberiza bruniceps

In the redheaded bunting Emberiza bruniceps, thyroidectomy inhibited premigratory fattening and nocturnal restlessness—two characteristics of avian migration—observed in caged birds during the premigratory period (March/April). Thyroxine (T₄) and triiodothyronine (T₃) administration in thyroidectomized birds stimulated locomotor activity and restored the loss in body weight. Annual variations in circulating thyroid hormone concentrations revealed a significant rise in $\text{T}{}_3\text{T}{}_4$ ratio prior to spring migration in both years studied. This increase in circulating $\text{T}{}_3\text{T}{}_4$ ratio may be associated with the development of migratory disposition in this bird. There was no increase in circulating $\text{T}{}_3\text{T}{}_4$ ratio prior to autumnal migration, however, plasma T₄ increased significantly. Different thyroidal mechanisms are most likely involved in spring and fall migratory periods. While T₃ remained low throughout, apart from the characteristic spring rise, high T₄ levels in E. bruniceps were associated with periods of reproduction and molting, the latter coinciding partly with autumnal migration.     

Organization of the rat gamma-fibrinogen gene: alternative mRNA splice patterns produce the gamma A and gamma B (gamma ') chains of fibrinogen

In a variety of species, including rodents and man, the gamma chain of fibrinogen consists of two nonallelic forms, called gamma A and gamma B, or gamma and gamma '. We have found that these two fibrinogen gamma chains in the rat arise by translation of two mRNAs of 1700 and 2200 nucleotides, which are produced from a single gene by alternative splice patterns. The more abundant, gamma A chain mRNA is 1561 nucleotides long, excluding the polyadenylated region, and encodes a protein 83% homologous with the human gamma A chain. A hydrophobic "signal" polypeptide of 25 amino acids is present at the amino terminus. The gamma B (gamma ') mRNA is identical with the gamma A sequence with the exception of a 513 bp insert located 202 bp from the poly(A) extension. This 513 bp insert is identical to the seventh and final intron of the gamma-fibrinogen gene, and is located four codons prior to the termination codon for the gamma A chain. Translation into this sequence produces a unique 12 amino acid carboxylterminus in the rat gamma B (gamma ') polypeptide that is homologous with the known carboxylterminus of the human gamma B (gamma ') chain.     

Molecular cloning of cDNA for the alpha, beta, and gamma chains of rat fibrinogen. A family of coordinately regulated genes

Recently, we have found that defibrination of rats with Malayan pit viper venom induces a 10-38-fold increase in the levels of translatable fibrinogen mRNA in the liver. We have used this response to obtain cDNA clones for the three polypeptide chains of rat fibrinogen. A large cDNA library was created in pBR322 from induced rat liver polyadenylated RNA by the poly(dG, dC)-tailing method. Part of this library was screened using colony hybridization with [32P]cDNA prepared from induced and noninduced rat liver RNA. Colonies consistently giving a more intense signal with the induced [32P]cDNA were considered possible fibrinogen recombinants and were used for hybrid selection and translation of mRNA. In this way, cDNA clones for each of the three fibrinogen mRNA's were identified. Analysis of polyadenylated RNA by Northern blotting indicates that the three chains are synthesized from mRNA's of 2300, 2050, and 1950 nucleotides for the alpha, beta, and gamma chains, respectively. The fact tha each of the three chains has a separate mRNA indicates that the highly coordinated regulation of the three messages for rat fibrinogen does not occur by translation of a common cytoplasmic RNA.     

Resistance in sunflower and interaction with Bacillus thuringiensis for control of banded sunflower moth (Lepidoptera: Tortricidae)

Four sunflower accessions were compared with a susceptible check, hybrid '894', in the greenhouse to determine their resistance to the banded sunflower moth, Cochylis hospes Walsingham, and their interaction with Bacillus thuringiensis Berliner variety kurstaki. Antibiosis, expressed as lower larval weight, was detected in all of the accessions. In addition to being antibiotic, sunflower accession Ames 3291 was antixenotic to banded sunflower moth oviposition and exhibited an additional impact on larval weight when B. thuringiensis was applied. By itself, B. thuringiensis provided better control of banded sunflower moth than the resistance tested. However, banded sunflower moth-resistant sunflower would be a good option when B. thuringiensis or another insecticide is not applied, and it may prevent the economic threshold from being reached.     

Leydig cell number and function in the adult cynomolgus monkey (Macaca fascicularis) is increased by daily hCG treatment but not by daily FSH treatment

Daily treatment of adult cynomolgus monkeys with 450 i.u. hCG for 16 days resulted in a significant 163% increase in the number of Leydig cells, and a 9-fold rise in plasma testosterone concentrations. The number of proliferating Leydig cells was very low, even after 16 days of treatment with hCG. Daily FSH administration (2 injections of 15 i.u. per day) did not have any effect on the number of Leydig cells or plasma testosterone values. It can be concluded, therefore, that in adult cynomolgus monkeys daily hCG treatment results in an increase in the number of Leydig cells, which is mainly caused by the differentiation of precursor cells. Since plasma testosterone concentrations were increased to an even higher extent, the steroid production per Leydig cell was also stimulated.