Vasopressinergic and oxytocinergic pathways in the central nervous system

Recent data obtained by immunohistochemical and other anatomical tracing methods indicate that oxytocin and vasopressin pathways are much more complex and extensive than previously recognized. In addition to the classic magnocellular neurons that project from the supraoptic and paraventricular (PVN) nuclei to the posterior pituitary gland, generally smaller neurons in various parts of the PVN send vasopressin fibers to the portal capillary bed in the median eminence, or send oxytocin or vasopressin projections to other brain and spinal cord sites. In addition, vasopressin neurons are also found in the suprachiasmatic nucleus and may contribute to extrahypothalamic projection areas. Many of these axonal projections appear to form synapses with other neurons in forebrain, hindbrain, and spinal cord regions, which suggests roles for these peptides in neuronal communication. In brain stem and spinal cord, terminal fields include both parasympathetic and sympathetic regulatory centers. Oxytocin terminals are also found on large intracerebral arteries where the peptide may regulate cerebral blood flow.     

Rooting apple cultivars in vitro: Interactions among light,temperature, phloroglucinol and auxin

Delicious apple (Malus domestica Borkh.) and several of its strains, which have been difficult to root in vitro, were successfully propagated with rooting percentages up to 100%. The combination of treatments used to achieve this result included placing the shoots on rooting medium in the dark at 30°C for the first week of the rooting stage, then moving them to a regime of 16 hr light-8 hr dark at 25°C. The rooting medium contained half strength Murashige and Skoog salts plus 1.2 M thiamine HCl, 0.56 mM myo-inositol, 1 mM phloroglucinol (PG), 1.4 M indolebutyric acid (IBA), 1.3 M gibberellic acid (GA₃), 87.6 mM sucrose, and 7 g l^–1 Difco Bacto agar. Dark treatment applied during the proliferation stage (etiolation) was less effective than one applied at the beginning of the rooting stage. The optimum length of dark treatment during rooting was 4 to 7 days. Increasing the temperature from 25°C to 30°C improved rooting of Delicious, Royal Red Delicious, and Vermont Spur Delicious in the absence of PG but generally had less effect in the presence of PG. Further increase in temperature to 35°C stimulated rooting of Royal Red Delicious but reduced rooting of Vermont Spur Delicious. Transfer of the cuttings to auxin-free medium after 1 week had no effect on percentage rooting and increased the number of roots per cutting for only 1 of 4 cultivars tested and then only in the presence of PG. In general PG stimulated rooting of Delicious and its strains, but had no effect on Golden Delicious.     

Cyanophycin granule polypeptide protease in a unicellular cyanobacterium

An assay was developed to measure the proteolysis of cyanophycin granule polypeptide in crude extracts of a unicellular cyanobacterium. The substrate was radioactively labeled cyanophycin granule polypeptide formed by an unicellular cyanobacterium grown in the presence of chloramphenicol. Substrate polypeptide displayed identical chemical properties with polypeptide isolated from non-chloramphenicol-treated cells. Solubilization of radioactivity as arginine indicated hydrolysis of polypeptide. Radioactively labeled aspartate and arginine from hydrolyzed polypeptide was related to nmol amino acid using a combination of paper chromatography, liquid scintillation analysis, and ninhydrin quantitation. Protease activity was found in extracts of nitrogen-limited cells harvested 16–24 h after a nitrogen source was added back. Optimal pH for protease activity was 8.0 and optimum temperature was 35°C. Protease activity in crude extracts followed Michaelis-Menten kinetics with a V _max of 92 nmol arginine per 15 min/mg protein and a K _m of 2.1×10³ nmol arginine. Protease activity was inhibited by arginine and by high concentrations of aspartate.     

Cell surface antigens on erythroid cells: A comparison of normal and anemic (WW) mice

Cell surface antigens of normal and anemic ($\text{W}\text{W}$) mouse erythroid cells have been examined in cytotoxicity assays with two rat antisera. When tested on fetal liver cells, a rat anti-erythroblast serum recognized antigen(s) present on erythroid cells early in development, while rat anti-adult red blood cell serum recognized antigen(s) present on mature erythroid cells. Each of these sera had different activity on normal (+/+ or $\text{W}\text{+}$) as compared to anemic ($\text{W}\text{W}$) erythroid cells.     

The effect of nectar production on neighborhood size

Summary Bumblebee foraging behavior was observed on two plant species with similar floral and inflorescence structures. One species produces nectar while the other does not. Bees, upon visiting nectar producing flowers tend to empty them of nectar and by frequently moving between close neighbors, create a patchily distributed resource base. Bees maximize their foraging efficiency in such an environment by using an area-restricted searching behavior and flying distances inversely correlated with the quality of reward received. Pollen collecting bumblebees do not create a patchy environment and maximize their foraging efficiency by more consistently moving shorter distances. Pollen collecting bumblebees are significantly more likely to revisit flowers and to visit more flowers per inflorescence than are nectar gathering bumblebees. These differences in foraging behavior increase the neighborhood size for nectar producing species and make it increasingly unlikely that random drift will be a dominant mode of evolution in populations of these species.     

Responses to moisture stress in male and female plants of Rumex acetosella L. (Polygonaceae)

Summary Male and female plants of Rumex acetosella were grown on a moisture gradient to measure possible differences in the drought tolerance of the sexes. The growth of both sexes declined under water stress but males were significantly more drought tolerant. This could not be explained by greater water use efficiency in the male plants; measured rates of both photosynthesis and leaf conductance did not differ significantly between the sexes. Multiple discriminant analysis showed that the sexes differed at all moisture regimes in their overall patterns of biomass allocation. Males had proportionately greater investment in root and leaf tissue which could explain their growth advantage over females under water stress. Despite essentially equal water use efficiencies, on a per plant basis males, with more leaf and root biomass, could fix more carbon and more rapidly exploit the local water resource than females. Thus the pattern of biomass allocation rather than intrinsic physiological differences appears to explain the greater drought tolerance of male plants of Rumex acetosella.     

Analysis of histidine-containing dipeptides, polyamines, and related amino acids by high-performance liquid chromatography: application to guinea pig brain.

A procedure is described for coupling wheat germ agglutinin to cyanogen bromide-activated Sepharose to yield a lectin affinity column of high capacity. Covalent linkage of the lectin to the insoluble matrix is carried out in the presence of a mixture of β-1,4-linked N-acetylglucosamine oligosaccharides prepared from chitin. The lectin-affinity column specifically recognizes glycoproteins containing N-acetylglucosamine residues with the capacity of binding 0.6–1.0 mg of ovomucoid per milliliter of gel. The affinity column is stable (as determined by ovomucoid binding) and shows little loss in binding capacity or specificity after repeated usage. Important characteristics for the use of this column to purify glycoproteins are described.