Hypothalamic and hormonal control of photoperiodically induced vernal functions in the white-crowned sparrow,Zonotrichia leucophrys gambelii

Summary The effects of implantation of testosterone propionate (TP) in various sites in the hypothalamus on the photoperiodically induced vernal premigratory functions in the White-crowned Sparrows were investigated in order to assess the role of the hypothalamo-hypophysial-testicular axis in the induction of these responses.Implantation of glass capillary tubes containing TP in the basal infundibular nucleus (IN), in the median eminence, or in the pars distalis inhibited the photoperiodically induced increase in plasma levels of luteinizing hormone (LH), as measured by radioimmunoassay, and testicular growth. The effective implants significantly lowered the levels of LH in birds held on nonstimulatory short days. These TP implants apparently inhibited release from the pars distalis of both LH and follicle-stimulating hormone (FSH). It is concluded that the site of sensitivity in the negative feedback by testosterone is either the basal IN or the pars distalis, or both. The implants of TP that inhibited the increase in plasma LH and testicular growth completely did not prevent the birds from fattening.These investigations were supported, in part, by research grants from the National Institutes of Health (HD-6527) and National Science Foundation (BMS 79-13933) to Professor Donald S. Farner. This paper is based on a dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy from the University of WashingtonThe author is grateful to Professor Donald S. Farner for his guidance throughout the course of these investigations. The assistance of Mr. Philip W. Mattocks, Jr. in performing radioimmunoassays is sincerely appreciated     

Effect of drought on proteins and isoenzymes in rice during germination

Two drought tolerant varieties TKM-1 and TKM-2 and two drought susceptible varieties Jaya and Improved Sabarmati of rice were studied for soluble protein pattern and isoenzymes of malate dehydrogenase, glutamate dehydrogenase, esterase and peroxidase during germination at different water stress. MDH, GDH and esterase patterns were not affected, but the soluble proteins were changed. Peroxidase isoenzyme pattern from drought tolerant and susceptible varieties showed characteristic differences. The intensity of bands with higher electrophoretic mobility decreased in Jaya and Improved Sabarmati while in TKM-1 and TKM-2 the intensity of these bands did not change much after 72 hr water stress. In shoots of Jaya and Improved Sabarmati, the activity of the peroxidase isoenzymes decreased more than in TKM-1 and TKM-2 shoots with increase in water stress.     

The effects of different horticultural practices on the chemical flavour composition of some cabbage cultivars

Variations in the chemical flavour composition of three cultivars of cabbage were determined for plants of different horticultural histories. In some i     

Opsonizing effect of serum and albumin gland extracts on the elimination of human erythrocytes from the circulation of Helix pomatia

The removal of human erythrocytes of the A₁ and B types from the circulation of the gastropod Helix pomatia follows an exponential curve. The elimination of the nonself particles is apparently dependent on serum opsonins as preincubation of A₁ and B erythrocytes in Helix serum increases the rate of their clearance. This conclusion is supported by our finding that secondary doses of nonsensitized A₁ erythrocytes injected 12–19 hr after a similar primary dose are cleared very slowly; however, the clearance rate returns to normal if erythrocytes comprising the second dose are preincubated with Helix serum. Furthermore, the elimination of second-dose A₁ erythrocytes is strongly enhanced after their pretreatment with agglutinating extracts of the albumin glands from H. pomatia and Cepaea (Helix) nemoralis. On the other hand, no opsonizing effect was obtained by pre-incubating A₁ erythrocytes in the agglutinating extract of the sponge Aaptos papillata.     

NITRATE UPTAKE BY LAMINARIA LONGICRURIS (PHAEOPHYCEAE)1,2

Laminaria longicrucis De la Pylaie took up exogenous nitrate under both summer and winter conditions. During July and August no NO₃^- was detected in the ambient water or in algal tissues although it was present in both in February. Discs (2.3 cm diam.) of thin blade tissue were incubated with NO₃^- at four temperatures, with and without illumination. Similar values Jor NO₃^- uptake were found for both summer and winter collected plants when measured in light at 0 C. An apparent K of 4–6 μM was recorded for both types of plants; the V_max ranged from 7 to 10 μmol h^-1 g^-1 dry wt measured in ca. 1800 μW cm^-2 of cool-white fluorescent light. Uptake rates at 5 C were 66%, and at 0 C 30% of those for controls run at 15 C. The alga scavenged NO₃- from solutions <0.5 μM. Ammonia did not inhibit NO₃- uptake. Antibiotic pretreatment reduced NO₃- uptake by a maximum of 12%. Nitrite uptake was inhibited in proportion to the concentration of NO₃- in the medium.     

Effect of auxins on the formation of ubiquinone by tobacco plant cells in suspension culture

Ubiquinone (UQ) formation in BY-2 tobacco cells was especially promoted by a high concentration of 2,4-D. 2,4,5-T, MCP and NAA also promoted UQ formation in these cells. The UQ content in the cells cultured at high concentrations of 2,4-D was higher than that of controls throughout the culture period. The addition of 2,4-D at an early period in cell growth was very effective in promoting UQ formation, but addition at the stationary phase was ineffective. Cell growth was improved by adding phosphate to the medium but UQ content was decreased. UQ content decreased slowly during subculturing, whereas cell growth recovered gradually.     

Effects of narrow-beam irradiations with blue and far-red light on the timing of cell division in Adiantum gametophytes

Protonemata of the fern Adiantum capillusveneris L., grown as single-cell filaments under continuous red light, were irradiated with a narrow beam of blue light. Only irradiation of the region containing the nucleus induced cell division. Beams of 30 m in width, which corresponds to the diameter of the nucleus, or wider, were equally effective; beams 10 m wide or less were less effective. The results indicate that the nuclear region is the site of the blue- and near ultraviolet-light-absorbing pigment (P_B-NUV) which mediates the timing effect of cell division. In contrast, the effect of a narrow beam of far-red (FR) light, which delays the onset of the blue-light-induced cell division, was found to be present along the entire length of the protonema cell, including the largely vacuolated basal region of the latter. Polarized FR light having the electrical vector parallel to the protonema axis was less effective than that vibrating in other directions. These observations support the hypothesis that the phytochrome controlling the timing effect is localized in the plasma membrane.     

Anion and ionic strength effects upon the oxidation of cytochrome c by cytochrome c oxidase

Citrate and other polyanion binding to ferricytochrome c partially blocks reduction by ascorbate, but at constant ionic strength the citrate-cytochrome c complex remains reducible; reduction by TMPD is unaffected. At a constant high ionic strength citrate inhibits the cytochrome c oxidase reaction competitively with respect to cytochrome c, indicating that ferrocytochrome c also binds citrate, and that the citrateferrocytochrome c complex is rejected by the binding site at high ionic strength. At lower ionic strengths, citrate and other polyanions change the kinetic pattern of ferrocytochrome c oxidation from first-order towards zero-order, indicating preferential binding of the ferric species, followed by its exclusion from the binding site. The turnover at low cytochrome c concentrations is diminished by citrate but not the K_m (apparent non-competitive inhibition) or the rate of cytochrome a reduction by bound cytochrome c. Small effects of anions are seen in direct measurements of binding to the primary site on the enzyme, and larger effects upon secondary site binding. It is concluded that anion-cytochrome c complexes may be catalytically competent but that the redox potentials and/or intramolecular behaviour of such complexes may be affected when enzyme-bound. Increasing ionic strength diminishes cytochrome c binding not only by decreasing the ‘association’ rate but also by increasing the ‘dissociation’ rate for bound cytochrome c converting the ‘primary’ (T) site at high salt concentrations into a site similar kinetically to the ‘secondary’ (L) site at low ionic strength. A finite K_m of 170 μM at very high ionic strength indicates a ratio of $\text{K}{}^{\mathrm{\infty }}{}_{\mathrm{<mtext>M</mtext>}}\text{K}{}^0{}_{\mathrm{<mtext>M</mtext>}}$ of about 5000. It is proposed that anions either modify the E¹₀ of cytochrome c bound at the primary (T) site or that they perturb an equilibrium between two forms of bound c in favour of a less active form.     

Structural changes of isolated hepatocytes during treatment with digitonin

The structural changes accompanying digitonin-induced release of enzymes and metabolites from isolated hepatocytes have been studied by scanning and transmission electron microscopy. In the initial phase, characterized by total release of the cytosolic marker enzyme, lactate dehydrogenase, the plasma membrane was immediately damaged, rapidly followed by extensive damage to the endoplasmic reticulum. The shape of the cell, however, was maintained, and the mitochondria and nucleus remained tightly held together by the cytoskeleton. Mitochondria remained intact initially, whereas the cytosol became less electron dense and the nuclear chromatin was more dispersed. An intermediate phase was characterized by total release of adenylate kinase and most of the glucose-6-phosphatase, marker enzymes for the mitochondrial intermembrane space and the endoplasmic reticulum, respectively. The outer mitochondrial membrane was ruptured, but mitochondria maintained their normal matrix electron density. In the final phase, characterized by the beginning of citrate synthase release from the mitochondrial matrix space, the mitochondria became swollen, and only the nucleus, inner and outer mitochondrial membranes, and the cytoskeleton could be clearly distinguished. Although the plasma membrane could not be readily discerned in electron micrographs after the initial phase, the plasma membrane marker enzyme 5′-nucleotidase remained associated with digitonin-treated hepatocytes. Acetyl-CoA carboxylase was released much more slowly than lactate dehydrogenase, indicating some severe restriction on its release. The release of acetyl-CoA carboxylase closely paralleled the release of glucose-6-phosphatase. The controlled exposure of hepatocytes to digitonin, therefore, leads to the sequential release of soluble, compartmentalized cellular components and some membrane-bound components, but the mitochondrial membrane, cytoskeleton and the nucleoskeleton survive even long-term digitonin treatment.     

Acute abdominal vagotomy reduces drinking to peripheral but not central angiotensin II

Rats were tested two or three days after bilateral abdominal vagotomy or a laparotomy control procedure for their drinking responses to subcutaneous (1 mg-kg-1) or intracerebroventricular (100 ng) injections of angiotensin II. Vagotomy delayed the initiation of drinking and decreased 60-min water intake after subcutaneous, but not after intracerebroventricular, angiotensin II. This is the shortest postoperative interval in which the decrease in drinking after systemic injection of angiotensin II by abdominal vagotomy has been observed. The failure of vagotomy to decrease the response to intracerebroventricular angiotensin II demonstrates that the deficit after subcutaneous injection was not a nonspecific effect of recent vagotomy. These results, therefore, suggest that the abdominal vagus is necessary for normal drinking in response to circulating angiotensin II. Furthermore, the selective and acute onset of the deficit is consistent with the loss of a specific, rather than tonic facilitatory, vagal mechanism for drinking after elevation of circulating angiotensin II levels. Finally, the results imply that the physiological mechanisms which mediate the drinking responses to central and peripheral angiotensin are not identical.