Ultrastructure of pinealocytes of the cotton rat,Sigmodon hispidus

Summary Fine structural features of pinealocytes of cotton rats (Sigmodon hispidus) were examined. Golgi complexes, mitochondria, endoplasmic reticulum and polysomes are usual organelles seen in the perikaryonal cytoplasm of pinealocytes. Many non-granulated vesicles (40 to 80 nm in diameter) and a few granulated vesicles (about 100 nm in diameter) are associated with the Golgi cisternae. Occasionally, the cisternae contain granular materials. The perikaryonal cytoplasm of pinealocytes is characterized by the presence of inclusion bodies. These bodies are usually round in shape, not bounded by a limiting membrane and composed of fine granular or filamentous materials of high electron-opacity, which are similar in appearance to the substance seen in the nucleolonema. Pinealocyte processes, filled with abundant non-granulated vesicles and some granulated vesicles, are mainly found within the parenchyma and occasionally in perivascular spaces.Supported in part by NSF grant no. PCM 77-05734 and NIH grant no. HD-10202 (Morphology Core)     

Partial duplication of the long arm of chromosome 5: A case due to balanced paternal translocation and review of the literature

Summary A partial duplication of the distal segment of the long arm of chromosome 5 (q31qter) was observed in an infant with congenital malformations and dysmorphic features. The phenotypically normal father had a balanced translocation between the long arm of chromosome 5 and the short arm of chromosome 9: 46,XY,t(5;9)(q31;p24).The clinical and cytogenetic data obtained from six patients with partial duplications of two different long arm segments of chromosome 5 suggest that partial duplication of the distal long arm of chromosome 5 is associated with microcephaly, hypertelorism, epicanthus, strabismus, large upper lip, low-set, dysplastic ears, in addition to growth and psychomotor retardation. Partial duplication of the proximal part of the long arm of chromosome 5, on the other hand, is associated mainly with musculoskeletal abnormalities including muscle hypotrophy and hypotonia, scoliosis, lordosis, pectus carinatum, cubitus valgus, and genu valgum, in addition to psychomotor retardation. The dysmorphic features in this latter group include a bulging forehead, short nose, thick upper lip, low-set protruding ears and tapering, thin fingers.     

Evidence for separate PGD2 and PGF2α receptors in the canine mesenteric vascular bed

Potential interactions between PGD₂ and PGF_2α in the mesenteric and renal vascular beds were investigated in the anesthetized dog. Regional blood flows were measured with electromagnetic flow probes. PGD₂, PGF_2α and Norepinephrine (NE) were injected as a bolus directly into the appropriate artery, and responses to these agents were obtained before, during and after infusion of either PGD₂ or PGF_2α into the left ventricle. In each case, the infused prostaglandin caused vascular effects of its own. Left ventricular infusion of PGD₂ reduced responses to local injections of PGD₂ in the intestine, and a similar effect was observed for PGF_2α, suggesting significant receptor or receptor-like interactions for each of the prostanoids. However, systemic infusion of prostaglandin F_2α (20–100 ng/kg/min) had no effect on renal or mesenteric vascular responses to local injection of prostaglandin D₂. Similarly, PGD₂ administration (100 ng/kg/min) did not affect responses to PGF_2α in the intestine. The present results therefore suggest that these prostaglandins, i.e., D₂ and F_2α, act through separate receptors in the mesenteric and renal vascular beds. In addition, increased prostaglandin F_2α levels produced by infusion of F_2α reduced mesenteric but not renal blood flow, suggesting that redistribution of cardiac output might participate in side effects often observed with clinical use of this prostaglandin, such as nausea and abdominal pain.     

Heritability of Quasi-Continuous Skeletal Traits in a Randombred Population of House Mice

Heritabilities of 11 quasi-continuous skeletal traits were estimated in randombred house mice of three separate ages (1, 3, and 5 months). Three separate methods—regression, maximum likelihood correlation, and Falconer's Method—were used to obtain heritabilities for each of the separate age groups. Significant differences in the incidences of seven of the skeletal traits were found among ages, but they did not affect the heritability estimates, these estimates being pooled over ages. Heritabilities calculated from female parents were consistently higher (by about 13%) than those from male parents, indicating the presence of maternal effects. Mid-parent estimates made by all three methods gave very similar mean levels (0.17 — 0.20). Although low, this level compared favorably with that expected on the basis of previously estimated rates of accumulation of genetic variance. Maternal effects estimated from full sib correlations averaged 0.08.     

The metabolism of cycloartenol,lanosterol, 24-methylenecholesterol and fucosterol in Chlorella ellipsoidea

Lanosterol and cycloartenol labelled with tritium at C-2, and 24-methylenecholesterol and fucosterol labelled with tritium at C-2 and C-4 were fed to actively growing cultures of Chlorella ellipsoidea. Lanosterol and cycloartenol were converted to each of the five desmethyl sterols of C. ellipsoidea. Lanosterol was more efficiently incorporated than cycloartenol.Although there was some evidence for the reduction of the 24-methylene group, it was apparent that 24-methylene-cholesterol was converted primarily to the C₂₉ sterols, clionasterol and poriferasterol. Labelled fucosterol was reduced at the 24(28) double bond, producing clionasterol.     

Environmental and hormonal control of turion formation in Myriophyllum verticillatum

The turions of Myriophyllum verticillatum, an aquatic vascularplant, develop in the fall and function in propagation and dispersalas well as in over-wintering. Experiments with controlled evnironmentsindicate that both temperature and photoperiod regulate turionformation. Turions can be induced at 15°C or lower, butnot at 20°C. At 15°C, turions form in both 8- and 12-hrdays, but not in 16-hr days. Plants collected in early springdo not form turions readily in response to short days unlesspreviously exposed to long days; thus, turion formation is along-day-short-day response. This combination of photoperiodand temperature requirements probably prevents turion developmentin early spring when the temperature and photoperiod are similarto those in the fall. Treatment of plants with ABA (10^–5M) enhances turion development under marginally inductive conditions(12-hr days at 15°C) but cannot induce it under long days.On the other hand, the cytokinin benzyladenine (10^–5 M)blocks turion formation. GA3 (10^–5 M) and AMO-1618 (10^–5M) exert only small qualitative effects on turion development,while IAA (10^–5 M) retards it. During turion development,the level of ABAlike activity and of one or two unidentifiedinhibitors increases. Cytokinin activity decreases at the startof turion formation, increases during development, then decreasesat abscission. Thus two lines of evidence suggest that a decreasein cytokinin activity and an increase in acidic inhibitor activityplay important roles in turion induction. ¹Present address: Biological Station, University of Michigan,Ann Arbor, Michigan 48109, U. S. A. (Received December 1, 1975; )     

A synthesis of methyl 4,6-di-O-Methyl-α-d-mannopyranoside

A new route is described for preparing methyl 4,6-di-O-methyl-α-d-mannopyranoside (5) via methyl 2,3-di-O-p-tolylsulfonyl-α-d-mannopyranoside (3) as an intermediate. The retention of the mannopyranoside configuration and ring form was confirmed by proton n.m.r. spectroscopy and by m.s. of peracetylated aldononitrile derivatives. Mass-spectral fragmentation-pathways previously proposed were confirmed for 5-O-acetyl-2,3,4,6-tetra-O-methyl-, 2,5-di-O-acetyl-3,4,6-tri-O-methyl-, and 3,5-di-O-acetyl-2,4,6-tri-O-methyl-d-mannononitrile.     

Comparison of membrane organization in mitochondria from yeast and rat liver by nuclear magnetic resonance spectroscopy

Summary Proton magnetic resonance (PMR) and carbon-13 magnetic resonance (CMR) spectra of intact, unsonicated yeast and rat liver motochondria show differences which may be correlated with the composition of the membranes. High resolution PMR and CMR signals in intact yeast mitochondria have been assigned to regions of fluid lipid-lipid interaction on the basis of spectra of extracted lipid and protein, and the temperature dependence of NMR signals from the intact membrane. PMR spectra suggest that about 20% of total yeast phospholipid is in regions where both intramolecular fatty acid chain mobility and lateral diffusion of entire phospholipid molecules are possible. No such regions appear to exist in rat liver mitochondria. For both yeast and rat liver mitochondria, comparison of PMR and CMR spectra suggests that about 50% of phospholipid appears to be in regions where intramolecular fatty acid chain motion is considerable, but lateral diffusion is restricted. The remaining phospholipid appears to have little inter- or intramolecular mobility. Since NMR observation of lipid extracts from membranes indicates that phospholipid-sterol interactions do not account for the spectra of intact mitochondria, these effects are interpreted in terms of extensive lipid-protein interactions.     

A mechanistic study of aromatic hydroxylamine rearrangement in the rat

A modified crossover experiment was conducted to determine the mechanism of arylhydroxylamine rearrangement in the rat. When 1-hydroxy-1-phenyl-3-methylurea was incubated with fractionated liver homogenates or injected intraperitoneally in rats, 1-methylbenzimidazol-2-one was isolated as the major metabolite. Small amounts of the anticipated aminophenol, 1-(o-hydroxylphenyl)-3-methylurea were also isolated. Evidence is presented suggesting that hepatic isomerase-catalyzed rearrangements of hydroxylamines proceed via pathways analogous to those described for chemical model systems. Isomerization appears to be intermolecular involving the generation of a resonance-stabilized nitrenium ion capable of binding to amino acids and nucleotide bases.