Completion of mouse embryogenesis requires both the maternal and paternal genomes

Transplantation of pronuclei between one-cell-stage embryos was used to construct diploid mouse embryos with two female pronuclei ( biparental gynogenones ) or two male pronuclei ( biparental androgenones ). The ability of these embryos to develop to term was compared with control nuclear-transplant embryos in which the male or the female pronucleus was replaced with an isoparental pronucleus from another embryo. The results show that diploid biparental gynogenetic and androgenetic embryos do not complete normal embryogenesis, whereas control nuclear transplant embryos do. We conclude that the maternal and paternal contributions to the embryonic genome in mammals are not equivalent and that a diploid genome derived from only one of the two parental sexes is incapable of supporting complete embryogenesis.     

Basolateral plasma membrane localization of ouabain-sensitive sodium transport sites in the secretory epithelium of the avian salt gland

The distribution of Na+ pump sites (Na+-K+-ATPase) in the secretory epithelium of the avian salt gland was demonstrated by freeze-dry autoradiographic analysis of [(3)H] ouabain binding sites. Kinetic studies indicated that near saturation of tissue binding sites occurred when slices of salt glands from salt-stressed ducks were exposed to 2.2 μM ouabain (containing 5 μCi/ml [(3)H]ouabain) for 90 min. Washing with label-free Ringer's solution for 90 min extracted only 10% of the inhibitor, an amount which corresponded to ouabain present in the tissue spaces labeled by [(14)C]insulin. Increasing the KCl concentration of the incubation medium reduced the rate of ouabain binding but not the maximal amount bound. In contrast to the low level of ouabain binding to salt glands of ducks maintained on a freshwater regimen, exposure to a salt water diet led to a more than threefold increase in binding within 9-11 days. This increase paralleled the similar increment in Na+-K+-ATPase activity described previously. [(3)H]ouabain binding sites were localized autoradiographically to the folded basolateral plasma membrane of the principal secretory cells. The luminal surfaces of these cells were unlabeled. Mitotically active peripheral cells were also unlabeled. The cell-specific pattern of [(3)H]ouabain binding to principal secretory cells and the membrane-specific localization of binding sites to the nonluminal surfaces of these cells were identical to the distribution of Na+-K+-ATPase as reflected by the cytochemical localization of ouabain-sensitive and K+-dependent nitrophenyl phosphatase activity. The relationship between the nonluminal localization of Na+-K+-ATPase and the possible role of the enzyme n NaCl secretion is considered in the light of physiological data on electrolyte transport in salt glands and other secretory epithelia.     

The chemistry of thujone: I. Synthesis of insect juvenile hormone analogs via wittig coupling

Syntheses of the C₈ and C₁₀ olefinic units cis- and trans-5-ethyl-1-iodo-hex-4-enes and cis- and trans-7-ethyl-3-iodo-oct-6-enes are described. The Wittig coupling of such units with derivatives of α- and β-thujaketonic acids to give analogs of insect juvenile hormones is discussed.     

Nucleotide sequence and chromosomal location of Cab11 and Cab12, the genes for the fourth polypeptide of the photosystem I light-harvesting antenna (LHCI)

Tryptic peptide sequences from the 22 kDa polypeptide of tomato LHCI were used to construct a probe for gene cloning. The two genes cloned, cab11 and cab12, encode proteins of 251 and 250 residues that are 88% identical in overall amino acid sequence and 93% identical in the deduced mature protein. Each gene is present in a single copy per haploid genome; cab11 on chromosome 3 and cab12 on chromosome 6, and each has 2 introns located in similar positions to introns in other members of the Chl a/b-binding (CAB) protein gene family. Comparison of the amino acid sequences of LHCI, LHCII, CP29 and CP24 polypeptides confirms that all CABs share two regions of very high similarity which include the first and third transmembrane helices and the stroma-exposed sequences preceding them. However, near the N-terminus and between the conserved regions, the LHCI polypeptides have sequence motifs which appear to be PSI-specific.     

Measurements of the membrane water permeability (Lp) and its temperature dependence (activation energy) in human fresh and failed-to-fertilize oocytes and mouse oocyte.

The volumetric response of oocytes during rapid alterations of the extracellular osmotic environment were recorded using video microscopy. From these observations, the kinetics of water loss for human and mouse oocytes were determined over the temperature range 37 to 10 degrees C, including 37, 30, 20, and 10 degrees C. The changes in diameter of oocytes were measured over a 5-min period and a computer model was used to derive values for membrane water permeability (Lp) and inactive volume (Vb) and to compare the experimental data to the predicted values. The results for the mouse oocyte Lp were comparable to values determined by other methods. However the human data, for both failed-to-fertilize and fresh oocytes, have a wide range of values with large standard deviations. The Lp values at the various temperatures were used to calculate the Arrhenius activation energy (Ea). An Ea value of 9.48 kcal/mol was found for the fresh mouse oocyte, whereas the activation energy for human oocytes was extremely low, 3.73 kcal/mol for fresh oocytes and 1.93 kcal/mol for failed-to-fertilize oocytes.     

Effect of temperature shifts on gliding motility, adhesion, and fatty acid composition of Cytophaga sp. strain U67.

Gliding motility and flipping of 25 degrees C-adapted Cytophaga sp. strain U67 were inhibited when the bacteria were shifted to a less than or equal to 12 degrees C environment; motility was not blocked by a shift to 13 degrees C. Bacteria adapted to 4 degrees C were motile over the entire 4 to 25 degrees C temperature range tested. U67 adhesion to the substratum appeared to be unaffected by temperature shifts. Bacteria adapted to 4 degrees C had higher proportions of unsaturated and branched-chain fatty acids than did those grown at 25 degrees C. When 25 degrees C-adapted bacteria were subjected to a gradual temperature decline, the time of reappearance of gliding competence at 4 to 5 degrees C was correlated with these changes in fatty acid composition.     

Lipid analysis and fatty acid profiles of individual arterial atherosclerotic plaques

A protocol for the analysis of the lipid profile of microsamples of aortic tissue was developed. Lipid extraction was from intact tissue using acetone and chloroform/methanol (2/1, v/v). The extract was analyzed for total lipid, esterified cholesterol, cholesterol, triacylglycerol, and phospholipid. The extract was then processed to separate cholesteryl esters, triacylglycerol, and phospholipid which were hydrolyzed and the fatty acid composition was determined by GLC of pentafluorobenzyl ester derivatives. A lipid profile could be obtained on samples with a wet weight of 5 mg.     

AKR leukemogenesis: identification and biological significance of thymic lymphoma receptors for AKR retroviruses.

We have previously demonstrated that in vitro cell lines of mouse thymic lymphomas express surface receptors specific for the retrovirus that induced them. This study extends these observations to an analysis of receptor-bearing cells in the preleukemic and leukemic phases of spontaneous AKR thymic lymphomagenesis. AKR mice regularly begin expressing N-tropic retroviruses (as assayed on NIH fibroblasts by the XC plaque assay) in several tissues early in life; thymic lymphocytes also express these viruses, but are not autonomously transformed. Later thymic lymphomas emerge which are capable of metastasizing in the host of origin or transplanting leukemias into syngeneic hosts. Just prior to the appearance of thymic lymphomas, these mice also begin producing xenotropic retroviruses [as assayed in xenogeneic (For example, mink) fibroblasts], and concomitant with the appearance of the leukemias is the appearance of "recombinant" retroviruses which cause mink fibroblast foci (MCF); these viruses express elements of both N- and X-tropic virus envelopes and N-tropic viral gene products in their cores. Spontaneous AKR leukemias also produce other retroviruses which do not cause XC plaques or mink fibroblast foci; these are called SL viruses. The subject of this study was to test whether in vivo thymocytes in the preleukemic and leukemic periods also bear receptors specific for N-tropic, recombinant MCF and SL AKR retroviruses. We demonstrated that each spontaneous thymic lymphoma does bear receptors that bind viruses produced by the lymphomas and MCF-247 to a high degree and that bind N-ecotropic AKR retroviruses less well. Thymic lymphocytes predominating in the preleukemic period do not express detectable levels of receptors for either of the viruses. In some mice, receptor-positive cells co-exist with receptor-negative cells; only the receptor-positive cells are capable of transplanting leukemia to syngeneic hosts. We conclude that the presence of specific cell surface receptors for lymphoma cell-produced and recombinant AKR retroviruses is a marker for leukemia in these hosts.     

Metabolic modulation of neurotransmitter release--adenosine, adenine nucleotides, potassium, hyperosmolarity, and hydrogen ion.

Evidence has accumulated that several factors, which have been proposed as mediators of exercise hyperemia, can modulate adrenergic neurotransmission in blood vessels. Adenosine and the adenine nucleotides depress the response of isolated blood vessels of the dog to nerve stimulation more than that to exogenous norepinephrine; this difference is explained by a decreased release of the neurotransmitter. Potassium, hyperosmolarity, and acidosis also depress adrenergic neurotransmission in isolated veins. These results are consistent with the hypothesis that metabolic changes in the vicinity of the adrenergic neuroeffector junction are capable of decreasing the output of neurotransmitter to the blood vessels in the exercising muscle.