A promoter that drives transgene expression in cerebellar Purkinje and retinal bipolar neurons

A genomic clone encoding the Purkinje cell-specific L7 protein has been isolated and utilized to drive the expression of beta-galactosidase in mice. Three independent transgenic lines, germ line transformed with an L7-beta-galactosidase fusion gene, exhibit beta-galactosidase expression in both cerebellar Purkinje cells and retinal bipolar neurons. This distribution is the same as that previously determined for the L7 protein by immunohistochemistry. The transgenic murine lines can be used to obtain populations of marked Purkinje and bipolar neurons. Similar L7 promoter constructs can be used to express other foreign genes specifically in these two classes of neurons.     

Glazed lunar rocks: origin by impact

The glassy coating of lunar rock 12017 is enriched in 15 trace elements relative to the crystalline interior. It apparently consists chiefly of shock-melted rock, somewhat richer in rare earth elements and alkali metals than rock 12017 itself. The glass has been contaminated by about 0.5 percent carbonaceous-chondrite-like material or, alternatively, by a mixture of 0.06 to 0.3 percent fractionated meteoritic material and approximately 10 to 15 percent local soil. The glazing seems to represent molten material splashed from a nearby meteorite impact and not in situ melting by a sudden increase in solar luminosity.     

A new mechanism for the formation of meteoritic kerogen-like material

The carbon in ancient carbonaceous chondritic meteorites is mainly in a hydrocarbon composite similar to terrestrial kerogen, a cross-linked structure of aliphatic and aromatic hydrocarbons. Until recently, the composite has been commonly thought to have been produced in the early solar nebula by a Fischer-Tropsch-type process, involving the catalytic synthesis of hydrocarbons from carbon monoxide and hydrogen on grain surfaces. Instead, the aromatic hydrocarbons may form in gas-phase pyrolysis of simple aliphatics like acetylene and methane by a mechanism developed recently to explain formation of soot in combustion and of aromatic molecules in circumstellar envelopes. Nonequilibrium chemical kinetic calculations indicate that this mechanism can produce meteoritic aromatics if the initial concentration of simple hydrocarbons in the solar nebula was sufficiently but not unreasonably high.     

Diagnostic ultrasound and sister chromatid exchanges: failure to reproduce positive findings

Human lymphocytes were exposed in vitro to ultrasound from two clinical devices, one of which was previously reported to have increased the frequency of sister chromatid exchanges. The ultrasonic exposures had no significant effect on the frequency of sister chromatid exchanges from three blood donors. Exposure to ultrasound also had no effect on cell cycle progression. A concomitant positive control (mitomycin C) resulted in a significant increase in sister chromatid exchanges.     

A Model for Agro-Economic Analysis of Soil pH Mapping

Core soil sampling followed by laboratory analysis is the traditional method used to map soil pH prior to variable rate application (VRA) of lime on cropland. A recently developed automated soil sampling system capable of measuring soil pH on-the-go has significantly increased sampling resolution. However, adoption of such systems must be justified economically. This paper presents a method for assessing the economic benefit from automated mapping of soil pH prior to variable rate lime application. In this work, geostatistical, agronomic, and economic methods were used to generate a comprehensive numerical model for quantitative assessment of the net return over cost of liming for different lime management strategies. The strategies included: automated pH mapping, manual grid soil sampling, and whole field sampling used in combination with either variable or fixed rate liming. The model was demonstrated using a simulated field with known average pH and semivariogram model. The analysis showed the largest benefit ($6.13ha^–1year^–1) from using VRA with automated soil pH mapping versus VRA based on 1ha (2.5acres) manual grid point sampling for the selected simulated field conditions. A sensitivity analysis demonstrated that for a wide range of field conditions and crop prices, VRA plus automated mapping promises higher relative benefits than VRA based on either manual grid point or grid cell sampling.     

Individual tumors of multifocal EB virus-induced malignant lymphomas in tamarins arise from different B-cell clones

Cotton-top tamarins were inoculated with sufficient Epstein-Barr virus to induce multiple tumors in each animal within 14 to 21 days. The tumors consisted of large-cell lymphomas that contained multiple copies of the Epstein-Barr virus genome and generated Epstein-Barr virus-carrying cell lines showing no detectable consistent chromosomal abnormality. Hybridization of tumor DNA with immunoglobulin gene probes revealed that each lymphoma was oligo- or monoclonal in origin and that individual tumors from the same animal arose from different B-cell clones. Thus the virus induced multiple transformation events in tamarins in vivo to cause malignant tumors resembling the Epstein-Barr virus-associated lymphomas of patients with organ transplants.