Effect of acute ACTH administration on plasma steroid levels in the dog

Production of adrenal steroids in intact and castrated dogs is stimulated acutely by ACTH. While the increase in plasma cortisol, 17-hydroxypregnenolone and 17-hydroxyprogesterone is not affected by castration, the increment of dehydroepiandrosterone is totally abolished. On the other hand, administration of 17-hydroxypregnenolone in adrenalectomized dogs caused an increase in plasma C-19 steroids such as dehydroepiandrosterone, androstenedione and testosterone indicating that this C-21 progestin in plasma is rapidly converted. The site of this conversion is likely the testis. Furthermore, acute hCG administration in adrenalectomized dogs resulted in a marked increase in the levels of plasma 17-hydroxypregnenolone and dehydroepiandrosterone. However, our data show an ACTH-induced rise in 5-androstene-3 beta. 17 beta-diol in intact and castrated dogs, thus suggesting that this steroid is a good parameter to assess in the stimulation of adrenal steroidogenesis by ACTH.     

Metabolism of tritiated C19 steroids by shionogi mouse mammary tumors

In the present report, the metabolism of dehydroepiandrosterone, 5-androstene-3β, 17β-diol and androstenedione has been studied in two different Shionogi tumors, one is androgendependent (“androgen sensitive”) and grows in intact male mice and the other is apparently androgen-independent (“androgen insensitive”) since the cells continue to grow in castrated antiandrogen (Flutamide) treated male animals. Our data clearly show that both the sensitive and insensitive tumors contain 3β-hydroxysteroid Δ⁵-Δ⁴ isomerase which causes the transformation of C₁₉ steroids into potent androgenic steroids. However, the androgen sensitive tumor is able to convert 5-androstene-3β, l7β-diol into 2-hydroxyestrogens while the rate of conversion is extremely low in the insensitive tumor. Most interestingly, the production of 5α-reduced steroids observed in both tissues was clearly higher in insensitive tumor homogenates.     

Behavioural and electrophysiological responses by reproductive female Neogobius melanostomus to odours released by conspecific males

Behavioural and electrophysiological responses of reproductive and non‐reproductive female round gobies Neogobius melanostomus to water previously occupied by male round gobies (reproductive male water) were compared. Reproductive females spent more time than non‐reproductive females in a tank near the input of water conditioned from reproductive males. Also, reproductive females swam significantly faster than non‐reproductive females, suggesting that reproductive male odour may have activated spawning behaviour. Olfactory epithelial field potential measurement (electro‐olfactogram, EOG) showed that reproductive male water was a potent olfactory stimulus to reproductive females, but not to non‐reproductive females. Reproductive females responded significantly more than non‐reproductive females to solid‐phase (octadecylsilane) extracts of reproductive male water. Also, when these extracts were separated on reverse phase high performance liquid chromatography (HPLC), reproductive females showed noticeably greater responses than non‐reproductive females to the fractions that eluted between 30 and 40 min. The behavioural data support the hypothesis that reproductive male round gobies release compounds into the water that attract potential mates. The EOG data indicate that these compounds can be quantitatively extracted from the water and be partially purified by HPLC. The evidence is not sufficient to indicate whether or not the compounds are steroids. The relatively early elution time on HPLC, however, suggests that if these compounds are steroids, then it is more likely that they will be conjugated rather than free steroids.     

Genomic analysis of Pediococcus starter cultures used to control Listeria monocytogenes in turkey summer sausage.

The pulsed-field technique of clamped homogeneous electric field electrophoresis was employed to characterize and size genomic DNA of three pediocin-producing (Ped+) and two non-pediocin-producing (Ped-) strains of Pediococcus acidilactici. Comparison of genomic fingerprints obtained by digestion with the low-frequency-cleavage endonuclease AscI revealed identical restriction profiles for four of the five strains analyzed. Summation of results for 10 individually sized AscI fragments estimated the genome length to be 1,861 kb for the four strains (H, PAC1.0, PO2, and JBL1350) with identical fingerprints. Genomic analysis of the pediocin-sensitive, plasmid-free strain P. acidilactici LB42 with the unique fingerprint revealed nine AscI fragments and a genome length of about 2,133 kb. Ped- (JBL1350) and Ped+ (JBL1095) starter cultures (one each) were used to separately prepare turkey summer sausage coinoculated with a four-strain Listeria monocytogenes mixture (ca. 10(5) CFU/g). The starter cultures produced equivalent amounts of acid during fermentation, but counts of L. monocytogenes were reduced to a greater extent in the presence of the Ped+ starter culture (3.4 log10 unit decrease) than in the presence of the Ped- starter culture (0.9 log10 unit decrease). Although no listeriae were recovered from sausages following the cook/shower, appreciable pediocin activity was recovered from sausages prepared with the Ped+ strain for at least 60 days during storage at 4 degrees C. The results of this study revealed genomic similarities among pediococcal starter cultures and established that pediocins produced during fermentation provide an additional measure of safety against listerial proliferation in turkey summer sausage.     

Regeneration of Transgenic Soybean (Glycine max) Plants from Electroporated Protoplasts

Transgenic soybean (Glycine max [L.] Merr.) plants were regenerated from calli derived from protoplasts electroporated with plasmid DNA-carrying genes for a selectable marker, neomycin phosphotransferase (NPTII), under the control of the cauliflower mosaic virus 35-Svedberg unit promoter, linked with a nonselectable mannityl opine synthesis marker. Following electroporation and culture, the protoplast-derived colonies were subjected to kanamycin selection (50 micrograms per milliliter) beginning on day 15 for 6 weeks. Approximately, 370 to 460 resistant colonies were recovered from 1 × 10⁶ electroporated protoplasts, giving an absolute transformation frequency of 3.7 to 4.6 × 10⁻⁴. More than 80% of the kanamycin-resistant colonies showed NPTII activity, and about 90% of these also synthesized opines. This indicates that the linked marker genes were co-introduced and co-expressed at a very high frequency. Plants were regenerated from the transformed cell lines. Southern blot analysis of the transformed callus and leaf DNA demonstrated the integration of both genes. Single-plant assays performed with different plant parts showed that both shoot and root tissues express NPTII activity and accumulate opines. Experiments with NPTII and mannityl opine synthesis marker genes on separate plasmids resulted in a co-expression rate of 66%. These results indicate that electroporation can be used to introduce both linked and unlinked genes into the soybean to produce transformed plants.     

Action of acetazolamide on the chick embryo during late development.

Acetazolamide was injected into chick embryos on the 14th or 15th day of incubation. Doses ranging between 5 and 10 mg per egg produced a retardation in the growth of long bones. The affected bones contained a normal proportion of mineral as determined by ashing and presented a normal histological picture. On the basis of these findings, it is suggested that the alterations were not due to a specific direct effect of the drug on bones. The incorporation of 131-I by the thyroid glands of acetazolamide-injected embryos was analyzed radioautographically and quantitated on the same 6 mu-paraffin sections, with a thin window Geiger counter. The incorporation appeared notably reduced 3 h after the injection of acetazolamide and the reduction persisted for a least 24 h.the electron microscopical observation of thyroid follicular cells from similarly treated embryos showed that the cytological characteristics indicating an active protein synthesis were unmodified with respect to those found in control embryos. These results may indicate that acetazolamide inhibits the iodination of the throid hormone without interfering with the synthesis of the globulin. It is suggested that the growth retardation observed in the embryos treated with acetazolamide may be secondary to the action of the drug on the thyroid gland, although this action appears to be a transitory one.     

Schistosomiasis: Evaluation of the indirect fluorescent antibody,complement fixation,and slide flocculation tests in screening for schistosomiasis

Foreign Service personnel undergo pertinent parasitologic examinations upon return from foreign duty posts. Under this program, 2800 sera have been evaluated for schistosomiasis in this laboratory. The majority of individuals tested were considered to have limited exposure to schistosomiasis, although a few indigenous people from endemic areas also were screened. Nonindigenous populations usually gave stronger serological reactions than did indigenous populations. A comparison was made between those having protozoan and helminthic infections and those that were negative parasitologically. A number of subjects with tissue-phase helminths were evaluated and consistently gave strong reactions in the indirect fluorescent antibody (IFA) tests. On the other hand, there was no characteristic pattern observed in individuals with low serum titers. The IFA test proved to be highly sensitive and sufficiently specific for screening, provided that low background reactions were disregarded (i.e., when +/? and 1+ reactions were ignored at low serum dilutions). Thus, the IFA test was the method of choice for screening. Recourse to the complement fixation (CF) and slide flocculation (SF) tests, however, was necessary for definitive diagnosis. In view of the differences in the antigens and the serodiagnostic technics used in this survey, absolute correlation of test results could not be expected. Nevertheless, the three procedures (IFA, CF, and SF) showed excellent correlation in proven cases of schistosomiasis.     

Competitive dominance of wild and domestic Norway rats (Rattus norvegicus)

The objective was to determine differences in the relative dominance of wild and domestic Norway rats (Rattus norvegicus) when competing for food in inter-stock, round-robin pairings. Each day, after food-deprivation, wild and domestic rats were individually placed in a testing arena containing a slice of apple. On day 20 and every fourth day thereafter, eight wild-domestic pairs were allowed to compete for the apple. Domestic subjects spent more time eating than did wild rats and were more often dominant. Competition tended to wane over test days in response to defeat in earlier trials. The outcome of competition trials was not changed by increasing the extent of food deprivation together with continuous pairing. A reduction in social inhibitions accompanying the domestication process provides the best explanation for the enhanced competitive potential of the domestic rat.