Divergence of flowering genes in soybean

Soybean genome sequences were blasted with Arabidopsis thaliana regulatory genes involved in photoperiod-dependent flowering. This approach enabled the identification of 118 genes involved in the flowering pathway. Two genome sequences of cultivated (Williams 82) and wild (IT182932) soybeans were employed to survey functional DNA variations in the flowering-related homologs. Forty genes exhibiting nonsynonymous substitutions between G. max and G. soja were catalogued. In addition, 22 genes were found to co-localize with QTLs for six traits including flowering time, first flower, pod maturity, beginning of pod, reproductive period, and seed filling period. Among the genes overlapping the QTL regions, two LHY/CCA1 genes, GI and SFR6 contained amino acid changes. The recently duplicated sequence regions of the soybean genome were used as additional criteria for the speculation of the putative function of the homologs. Two duplicated regions showed redundancy of both flowering-related genes and QTLs. ID 12398025, which contains the homeologous regions between chr 7 and chr 16, was redundant for the LHY/CCA1 and SPA1 homologs and the QTLs. Retaining of the CRY1 gene and the pod maturity QTLs were observed in the duplicated region of ID 23546507 on chr 4 and chr 6. Functional DNA variation of the LHY/CCA1 gene (Glyma07g05410) was present in a counterpart of the duplicated region on chr 7, while the gene (Glyma16g01980) present in the other portion of the duplicated region on chr 16 did not show a functional sequence change. The gene list catalogued in this study provides primary insight for understanding the regulation of flowering time and maturity in soybean.     

Manganese-Enhanced MRI Reflects Both Activity-Independent and Activity-Dependent Uptake within the Rat Habenulomesencephalic Pathway

Manganese-enhanced magnetic resonance imaging (MEMRI) is a powerful technique for assessing the functional connectivity of neurons within the central nervous system. Despite the widely held proposition that MEMRI signal is dependent on neuronal activity, few studies have directly tested this implicit hypothesis. In the present series of experiments, MnCl₂ was injected into the habenula of urethane-anesthetized rats alone or in combination with drugs known to alter neuronal activity by modulating specific voltage- and/or ligand-gated ion channels. Continuous quantitative T1 mapping was used to measure Mn²⁺ accumulation in the interpeduncular nucleus, a midline structure in which efferents from the medial habenula terminate. Microinjection of MnCl₂ into the habenular complex using a protocol that maintained spontaneous neuronal activity resulted in a time-dependent increase in MEMRI signal intensity in the interpeduncular nucleus consistent with fast axonal transport of Mn²⁺ between these structures. Co-injection of the excitatory amino-acid agonist AMPA, increased the Mn²⁺-enhanced signal intensity within the interpeduncular nucleus. AMPA-induced increases in MEMRI signal were attenuated by co-injection of either the sodium channel blocker, TTX, or broad-spectrum Ca²⁺ channel blocker, Ni²⁺, and were occluded in the presence of both channel blockers. However, neither Ni²⁺ nor TTX, alone or in combination, attenuated the increase in signal intensity following injection of Mn²⁺ into the habenula. These results support the premise that changes in neuronal excitability are reflected by corresponding changes in MEMRI signal intensity. However, they also suggest that basal rates of Mn²⁺ uptake by neurons in the medial habenula may also occur via activity-independent mechanisms.     

RESPONSE OF BUSH BEAN EXPOSED TO ACID MIST

Bush bean plants (Phaseolus vulgaris L. cv. Contender) were treated once a week for six weeks with simulated acid mist at five pH levels ranging from 5.5 to 2.0. Leaf injury developed on plants exposed to acid concentrations below pH 3 and many leaves developed a flecking symptom similar to that caused by ozone. An adaxial, interveinal bleached area resembling SO₂ injury also developed on some trifoliate leaves at the low pH treatments. Microscopic observation of injured trifoliates indicated that the palisade cells were plasmolyzed and that the chloroplasts lost structural integrity. Reductions in plant weight and chlorophyll content were detected across the pH gradient. Seed and pod growth were reduced at some intermediate acid depositions even though no visible foliar injury developed. Foliar losses of nitrogen, calcium, magnesium and phosphorous increased with decreases in acid mist pH, whereas foliar potassium concentrations were unaffected by acid mist treatment.     

Trends in sales of drugs for asthma in New Zealand,Australia, and the United Kingdom, 1975-81.

As part of an investigation into the recent epidemic of deaths from asthma in New Zealand, trends in the sales of drugs for asthma in New Zealand, Australia, and the United Kingdom during 1975-81 were examined. Data on sales of drugs were obtained from an international pharmaceutical market research organisation. A striking increase in sales of sympathomimetic aerosols, steroid aerosols, and theophylline per caput occurred in all three countries, with the greatest increase occurring in New Zealand. Sales of sodium cromoglycate also increased in New Zealand and the UK but fell in Australia. By 1981 New Zealand had the highest sales of all these drugs per caput. Explanations for the rising mortality from asthma in New Zealand despite large increases in drug sales need to be explored. Although the temporal association between mortality and sales of drugs suggests that direct drug toxicity is unlikely, there may be more subtle adverse effects of drug use.