Evidence for an increase in X-ray-induced translocation frequency in oocytes of caffeine-treated Drosophila females

0-8 h old Drosophila females carrying a reversed metacentric X chromosome and a suitably marked Y chromosome were treated or not with 0.2% caffeine and irradiated with 2000 R X-rays. In contrast with the reduction found in translocation frequency following 2000 R irradiation of the male mated with 0.2% caffeine-treated females, the frequency of interchanges in oocytes was significantly higher with caffeine as compared with controls.     

Glucose stimulated release of gastric inhibitory polypeptide from hamster small intestine: An in vitro model

A superfusion model was used to study in vitro gastric inhibitory polypeptide (GIP) release from hamster small intestinal mucosa. A 10% glucose solution, in both fed and fasted hamsters, produced a prompt, sustained, three-fold rise in mean GIP release. In contrast, superfusion of a solution of 10% mannitol did not alter release of the peptide. This model provides potential for elucidation of the mechanisms through which glucose and other agents release GIP and other gastrointestinal peptides.     

Restoration of a Forest Understory After the Removal of an Invasive Shrub, Amur Honeysuckle (Lonicera maackii)

The recruitment of native seedlings is often reduced in areas where the invasive Amur honeysuckle (Lonicera maackii) is abundant. To address this recruitment problem, we evaluated the effectiveness of L. maackii eradication methods and restoration efforts using seedlings of six native tree species planted within eradication and unmanipulated (control) plots. Two eradication methods using glyphosate herbicide were evaluated: cut and paint and stem injection with an EZ‐Ject lance. Lonicera maackii density and biomass as well as microenvironmental characteristics were measured to study their effects on seedling growth and survivorship. Mean biomass of Amur honeysuckle was 361 ± 69 kg/ha, and density was 21,380 ± 3,171 plants/ha. Both eradication treatments were effective in killing L. maackii (≥ 94%). The injection treatment was most effective on large L. maackii individuals (>1.5 cm diameter), was 43% faster to apply than cutting and painting and less fatiguing for the operator, decreased operator exposure to herbicide, and minimized impact to nontarget vegetation. Deer browse tree protectors were used on half of the seedlings, but did not affect survivorship or growth. After 3 years, survival of native seedlings was significantly less where L. maackii was left intact (32 ± 3%) compared with the eradication plots (p < 0.002). Seedling survival was significantly different between cut (51 ± 3%) and injected (45 ± 3%) plots. Species had different final percent survival and rates of mortality. Species survival differed greatly by species (in descending order): Fraxinus pennsylvanica > Quercus muehlenbergii ≥ Prunus serotina≥ Juglans nigra > Cercis canadensis > Cornus florida. Survivorship and growth of native seedlings was affected by a severe first‐year drought and by site location. One site exhibited greater spring soil moisture, pH, percent open canopy, and had greater survivorship relative to the other site (55 ± 2 vs. 30 ± 2%). Overall, both L. maackii eradication methods were successful, but restorationists should be aware of the potential for differential survivorship of native seedlings depending on species identity and microenvironmental conditions.     

An essential role for putrescine biosynthesis during meiotic maturation of amphibian oocytes

The objective of this study was to investigate the role of polyamines during meiotic maturation of Xenopus oocytes. The results indicate a rapid and significant increase in the activity of ornithine decarboxylase (ODC), the rate-limiting enzyme in the polyamine biosynthetic pathway, during the meiotic maturation induced by either progesterone or human chorionic gonadotropin (HCG). This increase in the enzyme activity was followed by an accumulation of putrescine without any effect on the levels of spermidine or spermine. The inhibition of ODC activity and the accumulation of putrescine levels by α-difluoromethyl ornithine (DFMO), a catalytic irreversible inhibitor of ODC, also resulted in the inhibition of maturation mediated by progesterone in Xenopus oocytes. DFMO caused an inhibition of both maturation and ovulation induced by HCG in ovarian fragments. This inhibition was readily reversible by exogenous supply of putrescine to the medium. These observations suggest that putrescine plays an important role during the meiotic maturation of amphibian oocytes.     

Effects of glycol structure on the transesterification equilibria of oxo-osmium(VI) esters

We report equilibrium data on reactions between the N,N,N′,N′-tetramethylethylenediamine oxo-osmium(VI) ester of thymine with a variety of polyhydroxylated compounds including sugars, glycosides, sugar alcohols, and nucleosides. Some rate data are also included. The cis-furanosidic nucleosides showed the largest equilibrium constants; among the pyranosidic systems, the cis (ae) structure was preferred.     

4-Hydroxybenzoate:Polyprenyl transferase and the prenylation of 4-aminobenzoate in mammalian tissues

The effect of variously substituted derivatives of 4-hydroxybenzoic acid on 4-hydroxybenzoate:polyprenyltransferase activity in mitochondrial preparations derived from rat liver and brain has been investigated. Catecholamines such as dihyroxyphenylalanine and norepinephrine showed a minor inhibition of the activity of the enzyme in brain mitochondrial preparations, 4-aminobenzoic acid and 4-chlorobenzoic acid proved to be the most potent inhibitors of the reaction. Inhibition by 4-hydroxymercuribenzoate indicated that -SH groups were essential for activity. Studies using ¹⁴C-labeled compounds further revealed that 4-aminobenzoic acid was inhibitory by virtue of its ability to serve as an alternate substrate for prenylation. The product of the prenylation is identified as 3-polyprenyl-4-aminobenzoate based on chromatographic characteristics of the products formed in liver mitochondria and Escherichia coli, the retention of the carboxyl group of 4-[carboxyl-¹⁴C]aminobenzoate, the incorporation of isopentenyl pyrophosphate, the effect of bacitracin, and the retention of the amino group. 4-Chlorobenzoic acid was not prenylated. A survey of rat tissues shows that heart tissue contains maximum polyprenyltransferase activity when compared to liver, kidney, spleen and brain. The significance of the above results is discussed.     

Urinary excretion of prostaglandin E2 and prostaglandin F2α in potassium-deficient rats

Potassium-deficiency was induced in rats by dietary deprivation of potassium. The animals became polyuric and urine osmolality decreased more then three-fold compared to controls. Urinary excretion of prostaglandin E₂ (PGE₂) and prostaglandin F_2α (PGF_2α) did not increase during 2 weeks of potassium depletion. Partial inhibition of renal prostaglandin synthesis by meclofenamate did not increase the urine osmolality after water deprivation. These results make unlikely the hypothesis that the polyuria of potassium-deficiency, is the result of enhanced renal synthesis of prostaglandins with subsequent antagonism of the hydro-osmotic effect of vasopressin. Male animals consistently excreted less PGE₂ than female animals.     

Heterotrissocladius boltoni sp.n., a new orthoclad from vernal pools and streams in Ohio,U.S.A. (Diptera: Chironomidae)

Heterotrissocladius boltoni sp.n. from Ohio, U.S.A., is described in both sexes and all stages. The species belongs in themarcidus group and is found in temporary streams and pools