Molecular evolution of mitochondrial 12S RNA and cytochrome b sequences in the pantherine lineage of Felidae

DNA sequence comparisons of two mitochondrial DNA genes were used to infer phylogenetic relationships among 17 Felidae species, notably 15 in the previously described pantherine lineage. The polymerase chain reaction (PCR) was used to generate sequences of 358 base pairs of the mitochondrial 12S RNA gene and 289 base pairs of the cytochrome b protein coding gene. DNA sequences were compared within and between 17 felid and five nonfelid carnivore species. Evolutionary trees were constructed using phenetic, cladistic, and maximum likelihood algorithms. The combined results suggested several phylogenetic relationships including (1) the recognition of a recently evolved monophyletic genus Panthera consisting of Panthera leo, P. pardus, P. onca, P. uncia, P. tigris, and Neofelis nebulosa; (2) the recent common ancestry of Acinonyx jubatus, the African cheetah, and Puma concolor, the American puma; and (3) two golden cat species, Profelis temmincki and Profelis aurata, are not sister species, and the latter is strongly associated with Caracal caracal. These data add to the growing database of vertebrate mtDNA sequences and, given the relatively recent divergence among the felids represented here (1-10 Myr), allow 12S and cytochrome b sequence evolution to be addressed over a time scale different from those addressed in most work on vertebrate mtDNA.      

Responses of a C3 and a C4 perennial grass to elevated CO2 and temperature under different water regimes

An experiment was carried out to determine the effects of elevated CO₂, elevated temperatures, and altered water regimes in native shortgrass steppe. Intact soil cores dominated by Bouteloua gracilis, a C₄ perennial grass, or Pascopyrum smithii, a C₃ perennial grass, were placed in growth chambers with 350 or 700 μL L^?1 atmospheric CO₂, and under either normal or elevated temperatures. The normal regime mimicked field patterns of diurnal and seasonal temperatures, and the high-temperature regime was 4 °C warmer. Water was supplied at three different levels in a seasonal pattern similar to that observed in the field. Total biomass after two growing seasons was 19% greater under elevated CO₂, with no significant difference between the C₃ and C₄ grass. The effect of elevated CO₂ on biomass was greatest at the intermediate water level. The positive effect of elevated CO₂ on shoot biomass was greater at normal temperatures in B. gracilis, and greater at elevated temperatures in P. smithii. Neither root-to-shoot ratio nor production of seed heads was affected by elevated CO₂. Plant tissue N and soil inorganic N concentrations were lower under elevated Co₂, but no more so in the C₃ than the C₄ plant. Elevated CO₂ appeared to increase plant N limitation, but there was no strong evidence for an increase in N limitation or a decrease in the size of the CO₂ effect from the first to the second growing season. Autumn samples of large roots plus crowns, the perennial organs, had 11% greater total N under elevated CO₂, in spite of greater N limitation.     

Histological and immunohistochemical effects of Curcuma longa on activation of rat hepatic stellate cells after cadmium induced hepatotoxicity

The liver is a target for toxic chemicals such as cadmium (Cd). When the liver is damaged, hepatic stellate cells (HSC) are activated and transformed into myofibroblast-like cells, which are responsible for liver fibrosis. Curcuma longa has been reported to exert a hepato-protective effect under various pathological conditions. We investigated the effects of C. longa administration on HSC activation in response to Cd induced hepatotoxicity. Forty adult male albino rats were divided into: group 1 (control), group 2 (Cd treated), group 3 (C. longa treated) and group 4 (Cd and C. longa treated). After 6 weeks, liver specimens were prepared for light and electron microscopy examination of histological changes and immunohistochemical localization of alpha smooth muscle actin (αSMA) as a specific marker for activated HSC. Activated HSC with a positive αSMA immune reaction were not detected in groups 1 and 3. Large numbers of activated HSC with αSMA immune reactions were observed in group 2 in addition to Cd induced hepatotoxic changes including excess collagen deposition in thickened portal triads, interlobular septa with hepatic lobulation, inflammatory cell infiltration, a significant increase in Kupffer cells and degenerated hepatocytes. In group 4, we observed a significant decrease in HSC that expressed αSMA with amelioration of the hepatotoxic changes. C. longa administration decreased HSC activation and ameliorated hepatotoxic changes caused by Cd in adult rats.     

Determination of Nitrogen in Living Patients

THE technique of in vivo activation analysis has been used in the sequential study of whole-body calcium¹. Neutrons are produced by bombarding a lithium target with 10 MeV protons from the 1.5 m Nuffield cyclotron. The patients, after being irradiated to a dose of about 1.5 rem, are transferred to a whole-body counter in which the activities induced in calcium, sodium and chlorine are monitored. We briefly describe here a new technique for making in vivo measurements on line by counting during the period of irradiation. In particular we have examined the feasibility of measuring the whole-body nitrogen content and of detecting trace amounts of the toxic element cadmium. Liquid phantoms simulating the conditions in the human body are used for these studies.     

Photoperiodic time signals during twilight

Abstract. Although daylength has a major effect on flowering and several other aspects of plant development, the actual environmental time signals for the beginning and the end of day are obscure. An intensive spectroradiometric study was carried out in three contrasting environments: namely, unshaded sites, a mature oak woodland and a sugar beet crop. Spectral photon distributions were obtained describing numerous twilight phases and intervening photoperiods throughout the year. From each, absolute photon fluence rates, photon fluence rate ratios and phytochrome photoequilibria were calculated. Although substantial changes in spectral composition occurred during twilight, they were less capable of providing reliable and accurate time signals than the absolute fluence rate; this was especially apparent beneath the canopies. Thus, spectral changes are unlikely to be valuable in photoperiodic perception. The results are discussed in relation to the possible involvement of the known plant photoreceptors in photoperiodism.     

Inter‐specific gene flow dynamics during the Pleistocene‐dated speciation of forest‐dependent mosquitoes in Southeast Asia

Tropical forests have undergone repeated fragmentation and expansion during Pleistocene glacial and interglacial periods, respectively. The effects of this repeated forest fragmentation in driving vicariance in tropical taxa have been well studied. However, relatively little is known about how often this process results in allopatric speciation, since it may be inhibited by recurrent gene flow during repeated secondary contact, or to what extent Pleistocene‐dated speciation results from ecological specialization in the face of gene flow. Here, divergence times and gene flow between three closely‐related mosquito species of the Anopheles dirus species complex endemic to the forests of Southeast Asia, are inferred using coalescent based Bayesian analysis. An Isolation with Migration model is applied to sequences of two mitochondrial and three nuclear genes, and 11 microsatellites. The divergence of An. scanloni has occurred despite unidirectional nuclear gene flow from this species into An. dirus. The inferred asymmetric gene flow may result from the unique evolutionary adaptation of An. scanloni to limestone karst habitat, and therefore the fitness advantage of this species over An. dirus in regions of sympatry. Mitochondrial introgression has led to the complete replacement of An. dirus haplotypes with those of An. baimaii through a recent (～62 kya) selective sweep. Speciation of An. baimaii and An. dirus is inferred to have involved allopatric divergence throughout much of the Pleistocene. Secondary contact and bidirectional gene flow has occurred only within the last 100 000 years, by which time the process of allopatric speciation seems to have been largely completed.     

The distribution and persistence of iprodione applied by thermal fogging in a glasshouse tomato crop

Deposits collected on filter paper after application of a ready-to-fog formulation of iprodione and the residues of iprodione washed from tomato leaves after fog and HV spray application were analysed by gas-liquid-chromatography. Relatively heavy deposits were found close to the fogging machine but the deposit became lighter with increasing distance from the machine and in positions lateral to the stream of fog. The deposit collected within the leaf canopy was considerably lighter than that collected above the plants. Residues of iprodione on plants treated with HV sprays were always considerably higher than on fogged plants given a comparable rate of application. After repeated treatment, a substantial build-up of residue was found, but the amount on fogged plants was approximately half that on plants treated with HV sprays. There was a good correlation between the residue found on plants at six positions within the glasshouses and the incidence of infection from artificial inoculations of Botrytis cinerea on petioles.     

Manipulation of IAA-Oxidase Activity and Auxin-Deficiency Symptoms in Intact Cotton Plants with Manganese Nutrition

Cotton (Gossypium hirsutum L. cv. Deltapine 15) seedlings were grown in solution culture in which the Mn²⁺ level was varied. Following an initial period, a series of shifts in manganese nutrition were employed, each lasting 14 days. Appearance was observed and fresh weight, IAA oxidase (IAAO), peroxidase and IAAO inhibitor levels were determined. After the initial 3 weeks of treatment, growth was negatively correlated with IAAO (or peroxidase) activity. All shifts in manganese nutrition resulted in predicted changes in IAAO activity, growth and plant appearance during a second 2-week period of the experiment. Continuously deficient plants exhibited highest leaf abscission and IAA oxidase activity, and lowest growth of all treatments. Plants shifted from deficient to control levels of Mn²⁺ exhibited a marked decline in IAAO activity, increase in growth and absence of leaf abscission. Plants shifted from borderline deficiency to deficient Mn²⁺ exhibited a major increase in IAAO activity, reduction in growth and extensive leaf abscission. Control and borderline toxicity plants maintained normal IAAO activity, growth, and appearance. During a final 2-week period, symptom expression was intensified. In particular, the initial borderline deficiency plants shifted to deficient levels of Mn²⁺ abscised most of those leaves that expanded after the shift in treatment. In addition, shifts of some plants to toxic Mn²⁺ levels during the third phase of the experiment produced a complete cycle of manipulation. Plants initially deficient in Mn²⁺ with high IAAO and low growth recovered growth and declined in IAAO when shifted to control Mn²⁺ and then suffered severe inhibition of growth and toxicity symptoms when shifted to high Mn²⁺. In all cases changes in enzyme activity, growth, leaf abscission and similar symptoms were most strongly expressed in the youngest tissue or that with the greatest potential for growth during the interval of a particular treatment. Since total growth, IAAO, leaf abscission, internode length and similar symptoms were consistently manipulated in both directions (increase or decrease in intensity or degree) by raising or lowering Mn²⁺ levels in the plant culture medium, we conclude that there is a causal relationship between IAAO and these responses that involves destruction of auxin.     

AN ELECTRON PARAMAGNETIC RESONANCE (E.P.R.) STUDY OF ENDOGENOUS TRANSITION METALS IN THE TERRESTRIAL SLUG DEROCERAS RETICULATUM

E.P.R. spectroscopy was used to detect and characterise transitionmetal ions, notably Fe and Mn, and organic free radicals withinthe tissues of the slug Deroceras reticulatum. Tissue Cu wasE.P.R. silent. The calcium complexes found within the varioussoft tissues and the shell were shown to be of the calcite configuration.It was suggested that the presence of the organic free radicalswithin the digestive gland and reproductive organ may be dueto the peroxidation of subcellular membrane lipids. (Received 15 October 1987; accepted 2 January 1988)     

CONCENTRATIONS OF METALS (Cu, Pb, Cd, Zn, Ca) IN SIX SPECIES OF BRITISH TERRESTRIAL GASTROPODS NEAR A DISUSED LEAD AND ZINC MINE

Heavy metal concentrations in 6 terrestrial slug species inhabitinga disused Pb/Zn mine site were measured by atomic absorptionspectrophotometry. Differences in metal accumulation patternswere such that the species could be ranked in order of overallmetal accumulation capability: Arion hortensis < Deocerasreticulatum < Milax budapestensis < Arion ater < Derocerascaruanac < Arion subfuscus. Species belonging to the samegenus were widely separated by this simple ranking scheme. Theresults are discussed in the context of inter-species competitionand resource partitioning, and cautionary comments are madeconcerning the utility of slugs as biomonitors of terrestrialheavy metal pollution. (Received 25 November 1987; accepted 2 January 1988)