Population genetic structure and landscape connectivity of the Eastern Yellowbelly Racer (<Emphasis Type="Italic">Coluber constrictor flaviventris</Emphasis>) in the contiguous tallgrass prairie of northeastern Kansas,USA

The tallgrass prairie of North America has undergone widespread habitat loss and fragmentation (<4% remains). The Flint Hills region of Kansas and Oklahoma is the largest tallgrass prairie remaining and therefore provides an opportunity to study the population genetic structure of grassland species in a relatively contiguous landscape and set a baseline for evaluating changes when the habitat is fragmented. We adopted a landscape genetics approach to identify how landscape structure affected dispersal, population genetic structure, and landscape connectivity of the Eastern Yellowbelly Racer (Coluber constrictor flaviventris) across a 13,500-km² landscape in northeastern Kansas, USA. The racer population had high allelic diversity, high heterozygosity, and was maintaining migration-drift equilibrium. Autocorrelation between genetic and geographic distance revealed that racers exhibited restricted dispersal within 3 km, and isolation-by-distance. Significant isolation-by-distance occurred at broad regional scales (>100 km), but because of sufficient gene flow between locations, we were unable to define discrete subpopulations using Bayesian clustering analyses. Resistance distance, which considers the permeability of habitats, did not explain significant variation in genetic distance beyond Euclidean distance alone, suggesting that racers are not currently influenced by landscape composition. In northeastern Kansas, racers appear to be an abundant and continuously distributed snake that perceives the landscape as well connected with no cover type currently impeding snake dispersal or gene flow.     

Side-on copper-nitrosyl coordination by nitrite reductase

A copper-nitrosyl intermediate forms during the catalytic cycle of nitrite reductase, the enzyme that mediates the committed step in bacterial denitrification. The crystal structure of a type 2 copper-nitrosyl complex of nitrite reductase reveals an unprecedented side-on binding mode in which the nitrogen and oxygen atoms are nearly equidistant from the copper cofactor. Comparison of this structure with a refined nitrite-bound crystal structure explains how coordination can change between copper-oxygen and copper-nitrogen during catalysis. The side-on copper-nitrosyl in nitrite reductase expands the possibilities for nitric oxide interactions in copper proteins such as superoxide dismutase and prions.     

The atomic structure of Mengo virus at 3.0 A resolution

The structure of Mengo virus, a representative member of the cardio picornaviruses, is substantially different from the structures of rhino- and polioviruses. The structure of Mengo virus was solved with the use of human rhinovirus 14 as an 8 A resolution structural approximation. Phase information was then extended to 3 A resolution by use of the icosahedral symmetry. This procedure gives promise that many other virus structures also can be determined without the use of the isomorphous replacement technique. Although the organization of the major capsid proteins VP1, VP2, and VP3 of Mengo virus is essentially the same as in rhino- and polioviruses, large insertions and deletions, mostly in VP1, radically alter the surface features. In particular, the putative receptor binding "canyon" of human rhinovirus 14 becomes a deep "pit" in Mengo virus because of polypeptide insertions in VP1 that fill part of the canyon. The minor capsid peptide, VP4, is completely internal in Mengo virus, but its association with the other capsid proteins is substantially different from that in rhino- or poliovirus. However, its carboxyl terminus is located at a position similar to that in human rhinovirus 14 and poliovirus, suggesting the same autocatalytic cleavage of VP0 to VP4 and VP2 takes place during assembly in all these picornaviruses.     

Iodine desorption from rice paddy soil

Laboratory experiments on the desorption phenomena of iodine from rice paddy soil under waterlogged conditions, with a special reference to soil redox potential (Eh) and pH, have been conducted. Radioiodine tracer (1251), added to the soil, was readily sorbed on it. At the beginning of the waterlogging, the iodine desorption was low. However, iodine was desorbed into soil solution with time. The iodine desorption was enhanced markedly by the addition of organic substances such as straw pieces and glucose to the soil. Cultivation of rice plants in soil also affected the iodine desorption, suggesting root exudates and/or root autolysis might be participating in the desorption process. Eh dropped considerably after soil was waterlogged due to microbial metabolisms. Particularly low Eh values were observed in soils with plants and also with added organic substances. A negative correlation was seen between the desorption and soil Eh. High desorption was frequently observed when the Eh dropped to about -100 mV or below. Due to the reducing conditions (low Eh) by waterlogging, iodine in soil was leached into the soil solution; consequently total iodine concentration in paddy soil was considerably lower than forest and upland field soils. These iodine desorption phenomena under anaerobic conditions should be considered in assessing transfer of the long-lived radioiodine (129I) in the environment, especially in rice fields and marshland.     

Coral reefs under rapid climate change and ocean acidification

Atmospheric carbon dioxide concentration is expected to exceed 500 parts per million and global temperatures to rise by at least 2 degrees C by 2050 to 2100, values that significantly exceed those of at least the past 420,000 years during which most extant marine organisms evolved. Under conditions expected in the 21st century, global warming and ocean acidification will compromise carbonate accretion, with corals becoming increasingly rare on reef systems. The result will be less diverse reef communities and carbonate reef structures that fail to be maintained. Climate change also exacerbates local stresses from declining water quality and overexploitation of key species, driving reefs increasingly toward the tipping point for functional collapse. This review presents future scenarios for coral reefs that predict increasingly serious consequences for reef-associated fisheries, tourism, coastal protection, and people. As the International Year of the Reef 2008 begins, scaled-up management intervention and decisive action on global emissions are required if the loss of coral-dominated ecosystems is to be avoided.     

The vitamin A requirement and the vitamin A status of growing cattle. 1. Studies of calves

Five experiments with 18 to 36 male calves each of the black and white dairy cattle breed (age: 14-21 days, initial live weight: approximately 45 kg per animal) were carried out in order to investigate the influence of various vitamin A supply (0-80,000 IU per 100 kg LW and day) on dry matter intake and weight gain as well as the vitamin A status of liver and blood plasma over 84 days. The calves consumed a diet free of carotene and vitamin A consisting of milk replacer, concentrate and chopped wheat straw. The calves were fed in three experiments for a longer time in order to observe the further vitamin A depletion. Nine animals consumed an unsupplemented ration, nine other one got 10,000 IU vitamin A per 100 kg LW and day. Biopsies of liver and plasma samples were taken from 4 animals per group every four weeks. The various vitamin A supplementation did not significantly influence the dry matter intake (Mean: 1.67; 1.48 to 1.80 kg DM per animal and day) and the weight gain of calves (Mean: 702, 599 to 770 g per animal and day). First vitamin A deficiency symptoms (reduced feed intake, decreased weight gain, diarrhoea etc.) were observed in animals of unsupplemented group after 100 days of experiments. After 84 days the vitamin A concentration of liver of animals of unsupplemented groups decreased to 1.3-32.2% compared with the begin of experiments (60.6-155.7 mumol/kg fresh matter). Up to 51% of initial concentration were found when 10,000 IU vitamin A per 100 kg LW and day were fed. About 25,000 IU vitamin A per 100 kg LW and day were required in order to keep the initial level of vitamin A concentration of liver. The plasma vitamin A concentration is unsuitable for estimation of vitamin A status of calves. The concentration of vitamin A of liver and plasma amounted to 114 mumol per kg and 0.25 mumol per litre at the begin of experiments. The vitamin A concentration of liver of unsupplemented group decreased to 20 mumol per kg, that of plasma increased to 0.28 mumol per 1 at the end. A strong vitamin A deficiency (liver concentration: less than 10 mumol/kg) may cause a decrease of vitamin A concentration of blood.     

Design automation for integrated circuits

With the ever-increasing complexity of integrated circuits, manual design methods have become intolerably slow and error-prone. The use of computers to automate some or all of the design process is necessary to minimize both design time and error incidence. In this article are discussed the design and fabrication of integrated circuits, selected techniques of design automation, and the problems associated with such automation.     

Irrigation and tillage effects on root development,water use and yield of wheat on coarse textured soils

Summary Rapid drying of surface layers of coarse-textured soils early in the growth season increases soil strength and restricts root growth. This constraint on root growth may be countered by deep tillage and/or early irrigation. We investigated tillage and irrigation effects on root growth, water use, dry matter and grain yield of wheat on loamy sand and sandy loam soils for three years. Treatments included all combinations of two tillage systems i) conventional tillage (CT) — stirring the soil to 10 cm depth, ii) deep tillage (DT) — subsoiling with a single-tine chisel down to 35–40 cm, 40 cm apart followed by CT; and four irrigation regimes, i) I₀ — no post-seeding irrigation, ii) I₁ — 50 mm irrigation 30 days after seeding (DAS), iii) I₂ — 50 mm irrigation 30 DAS and subsequent irrigations of 75 mm each when net evaporation from USWB class A open pan (PAN-E) since previous irrigation accumulated to 82 mm, and iv) I₃ — same as in I² but irrigation applied when PAN-E accumulated to 62 mm. The crop of wheat (Triticum aestivum L. HD 2329) was fertilized with 20kg P, 10kg K and 5kg Zn ha^–1 at seeding. The rate of nitrogen fertilization was 60 kg ha^–1 in the unirrigated and 120 kg ha^–1 in the irrigated treatments. Tillage decreased soil strength and so did the early post-seeding irrigation. Both deep tillage and early irrigation shortened the time needed for the root system to reach a specified depth. Subsequent wetting through rain/irrigation reduced the rate of root penetration down the profile and also negated deep tillage effects on rooting depth. However, tillage/irrigation increased root length density in the rooted profile even in a wet year. Better rooting resulted in greater profile water depletion, more favourable plant water status and higher dry matter and grain yields. In a dry year, the wheat in the DT plots used 46 mm more water, remained 3.3 °C cooler at grain-fill and yielded 68% more grain than in CT when unirrigated and grown in the loamy sand. Early irrigation also increased profile water depletion, more so in CT than DT. Averaged over three years, grain yield in DT was 12 and 9% higher than in CT on loamy sand and sandy loam, respectively. Benefits of DT decreased with increase in rainfall and irrigation. Irrigation significantly increased grain yield on both soils, but the response was greatly influenced by soil type, tillage system and year. The study shows that soil related constraints on root growth may be alleviated through deep tillage and/or early irrigation.     

Sex pheromone of the winter moth, a geometrid with unusually low temperature precopulatory responses

The sex pheromone for the winter moth, Operophtera brumata (L.), has been identified as the novel compound (Z,Z,Z)-1,3,6,9-nonadecatetraene. The male moths respond to the pheromone at low temperatures (4 degrees to 15 degrees C) and exhibit an upper response limit that coincides with the lower response limit for other reported moth sex pheromone systems. The pheromone attracted two other geometrid species, O. bruceata (Bruce spanworm) and O. occidentalis.     

Effects of green pruning on growth and stem shape of Eucalyptus nitens (Deane and Maiden) Maiden

An experiment was established in two high quality Eucalyptus nitens Deane and Maiden (Maiden) plantations in Tasmania. At the start of the experiment the trees were three years old and the plantations were on the point of canopy closure. Selected trees were pruned to remove 0, 50% or 70% of the lower green crown length, and each was surrounded by eight unpruned trees. The 50% treatment had no impact on height or diameter increment in the two years following treatment, but removal of 70% of the lower crown length resulted in significant decreases in both height and diameter increment. There were no changes in the height of 50%-pruned trees relative to the height of surrounding unpruned trees (relative height), and it was concluded that dominance would not be affected by this treatment. The relative height of 70%-pruned trees was less at one site, and this treatment may result in loss of dominance. Stem taper was generally unaffected by either pruning treatment. Changes in stem form were restricted to trees in the 70% pruning treatment and were only transient. It was concluded that removal of 50% of the lower green crown length is an appropriate level of pruning for the species provided that growth rates are rapid and pruning is timed to coincide with canopy closure. Since dominance was unaffected by this level of pruning, thinning at the time of pruning is unnecessary. It may be possible to minimise the impact on growth of higher levels of pruning by thinning at the time of pruning.