Generation and in vitro differentiation of a spermatogonial cell line

Spermatogenesis is the process by which spermatogonial stem cells divide and differentiate to produce sperm. In vitro sperm production has been difficult to achieve because of the lack of a culture system to maintain viable spermatogonia for long periods of time. Here we report the in vitro generation of spermatocytes and spermatids from telomerase-immortalized mouse type A spermatogonial cells in the presence of stem cell factor. This differentiation can occur in the absence of supportive cells. The immortalized spermatogonial cell line may serve as a powerful tool in elucidating the molecular mechanisms of spermatogenesis. Furthermore, through genomic modification and transplantation techniques, this male germ cell line may be used to generate transgenic mice and to develop germ cell gene therapy.     

Comparative micromorphology of two late Pleistocene paleosols (in the Paris Basin)

The micromorphology of two late Pleistocene paleosols in the Paris Basin, St. Pierre-les-Elbeuf and Bois du Moulin were studied in order to characterize their pedogenicand sedimentary processes and to reconstruct and interpret the pedosedimentary history and climate of each profile. The micromorphological observations of greatest interpretive value were the types of clayey and silty textural accumulations (argillans and siltans), pedality and porosity; of lesser value were papules, bioactivity and concretions.During the last interglacial period on both profiles developed a sol brun lessivé, comparable to those developed during the Holocene. With the onset of cold conditions of the last Glaciation, the two differentiate pedologically and sedimentologically. At Elbeuf, in the Seine Valley, we observe colluviation of silts and the development of grey forest soils with strong textural degradation under cold and moderately dry local conditions. At Moulin, on the plateau the grey forest phase is very weak and probably brief and is followed by a marked phase of churning and eluviation of silt; conditions were wetter than in the valley, such that the upland position protected the profile from colluvial truncation.The advantages of micromorphology in interpreting pedo-sedimentary sequences is discussed.     

Oxygen isotope ratios of juice water in Australian oranges and concentrates.

Australian orange juices from major growing regions have been surveyed over a 5 year period with a view to establishing a database of (18)O/(16)O isotope ratios against which retail samples can be tested for authenticity. The (18)O/(16)O ratios were found to follow a consistent pattern that had both a cyclic seasonal and a regional influence. Oxygen delta values ranged from a summer maximum of >+15 per thousand for oranges from inland regions to a winter minimum of approximately +1 per thousand for oranges grown in coastal areas. However, over a shorter time period, the range of values was markedly less than this. Concentrated orange juices, pulpwashes, and peel extracts, as well as other citrus types, were also tested. The effect of some industry practices that have an effect on (18)O/(16)O ratios was also investigated.     

Cinchonicine-derived alkaloids from the bark of the Peruvian Ladenbergia oblongifolia.

The isolation of cinchonicine-derived alkaloids epicinchonicinol (1), cinchonidicinol (2) and a mixture of dihydrocinchonicinol and dihydrocinchonidicinol (3) from the dried bark of Ladenbergia oblongifolia, is reported along with (1)H and (13)C-NMR data.     

Soil and plant water status under sprinkling and trickling

In a comparison of methods of irrigating tomatoes on the sand dunes of northern Sinai (El-Arish region), yields obtained by trickling were higher than those by sprinkling. The present study attempts to explain these results from a physical point of view. Before each irrigation and during a complete irrigation cycle measurements were made of soil moisture content, moisture tension in the root zone, and plant water potential. The amount of water applied was based on Class A pan evaporation. At 24 h after the end of an irrigation the soil moisture content was 4% by weight, regardless of the quantity of water applied. The soil moisture tension and the plant water potential were similar for both methods during the first 24 h after irrigation, but the values rose gradually and were higher at the end of the sprinkle irrigation cycle which lasted 3 days, than at the end of the daily trickle irrigation cycle. These differences in soil moisture tension affected the plant water potential and in turn plant development and yield.     

Pregnancy suppression by an antiserum to the sperm specific lactate dehydrogenase

An antiserum induced against the isozyme of lactate dehydrogenase (LDH-X) that is unique to spermatozoa reduced significantly the number of pregnancies in mice treated at varying times after they had mated. This effect of the antiserum occurred both prior to and following implantation. The fecundity of treated animals appeared to be normal in subsequent matings.     

Free Radicals and Reactive Molecules in Clathrate Cavities

Reactive molecules and free radicals, when located in the cavities of the water clathrate lattice, can be prevented from recombining at temperatures almost up to the decomposition point of the lattice. The active species are produced by selective photochemical dissociation of the guest molecules in the clathrate compounds. Data taken from water clathrates of H(2)S, CH(3)SH, and C(2)H(5)SH suggest that S(2), CH(3)S and C(2)H(5)S can be preserved in this way.