Procamacolaimus tubifer Gerlach, 1953, Procamacolaimus africanus sp.nov. and Eontolaimus capensis gen.nov., sp.nov., (Nematoda,Leptolaimidae) from South Africa

A female and three males of Procamacolaimus tubifer Gerlach, 1953 are described and illustrated from Cape Receife Beach, Port Elizabeth. P. africanus sp.nov. is also described fromCape Receife Beach. It is compared with P. tubifer which it resembles but from which it can be differentiated by length of the buccal cavity, amphid size and the shape of the spicules. Eontolaimus capensis gen.nov., sp.nov. is described, also from the same sandy beach. This new genus is related to Deontolaimus papillatus de Man, 1880 from which it can be distinguished, among other things, by the absence of a tooth-like structure in the buccal cavity and the presence of pre-anal tubuli.     

Dietary roughage sources affect lactating Holstein x Zebu cows under experimental conditions in Brazil: a meta-analysis

Tropical Animal Health and Production - To reduce costs, lactating cows are often fed a higher proportion of roughage and alternative feeds; however, such protocols may not lead to optimal milk...     

Wheat starch biosynthesis

Starch biosynthesis in plants involves the concerted action of a numberof enzymes, including ADPglucose pyrophosphorylase, starch synthases,branching enzymes and debranching enzymes. We report on the cloningand characterisation of genes encoding these enzymes from wheat and ontheir chromosomal locations. The prospects for manipulating wheat starchstructure and functionality using these genes is discussed.     

Differential exudation of two benzoxazinoids--one of the determining factors for seedling allelopathy of Triticeae species

Benzoxazinoids (Bx) are natural phytotoxins that function as chemical defense compounds in several species. The release of Bx by intact plant roots associated these compounds with root allelopathy in Triticeae species; however, the significance of exudate concentrations of Bx for plant-plant interactions is still a controversial question. A biological screening of 146 cultivars of four Triticeae species (Triticum aestivum L., Triticum durum Desf., Triticum spelta L., and Secale cereale L.) demonstrated a high cultivar dependence to suppress the root growth of Sinapis alba L. by root allelopathy in a dose-response bioassay. Only a few cultivars possessed a marked high or low allelopathic activity, whereby high-performance liquid chromatography-diode array detection analysis of root exudates revealed that these cultivars differed considerably in their ability to exude the two Bx aglucones, DIBOA [2,4-dihydroxy-2H-1,4-benzoxazin-3(4H)-one] and DIMBOA [2,4-dihydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one]. The total amount of DIBOA and DIMBOA exuded showed a significant correlation to the growth inhibition in bioassay with a statistically estimated contribution to the overall allelopathic effect of 48-72%. In a bioassay with pure phytotoxins, Bx concentrations consistent with the amounts quantified in the screening bioassay caused detrimental effects on S. alba and almost reproduced the statistically estimated contribution. The observed causal association between the allelopathic activity under laboratory conditions and the exudate concentrations of Bx suggests that this association might have implications for the interference of Triticeae species in natural plant communities.     

A dearth of dark matter in ordinary elliptical galaxies

The kinematics of the outer parts of three intermediate-luminosity elliptical galaxies were studied with the Planetary Nebula Spectrograph. The galaxies' velocity-dispersion profiles were found to decline with the radius, and dynamical modeling of the data indicates the presence of little if any dark matter in these galaxies' halos. This unexpected result conflicts with findings in other galaxy types and poses a challenge to current galaxy formation theories.     

A virus in a fungus in a plant: three-way symbiosis required for thermal tolerance

A mutualistic association between a fungal endophyte and a tropical panic grass allows both organisms to grow at high soil temperatures. We characterized a virus from this fungus that is involved in the mutualistic interaction. Fungal isolates cured of the virus are unable to confer heat tolerance, but heat tolerance is restored after the virus is reintroduced. The virus-infected fungus confers heat tolerance not only to its native monocot host but also to a eudicot host, which suggests that the underlying mechanism involves pathways conserved between these two groups of plants.     

The fate of Amazonian forest fragments: A 32-year investigation

We synthesize findings to date from the world’s largest and longest-running experimental study of habitat fragmentation, located in central Amazonia. Over the past 32 years, Amazonian forest fragments ranging from 1 to 100 ha have experienced a wide array of ecological changes. Edge effects have been a dominant driver of fragment dynamics, strongly affecting forest microclimate, tree mortality, carbon storage, fauna, and other aspects of fragment ecology. However, edge-effect intensity varies markedly in space and time, and is influenced by factors such as edge age, the number of nearby edges, and the adjoining matrix of modified vegetation surrounding fragments. In our study area, the matrix has changed markedly over the course of the study (evolving from large cattle pastures to mosaics of abandoned pasture and regrowth forest) and this in turn has strongly influenced fragment dynamics and faunal persistence. Rare weather events, especially windstorms and droughts, have further altered fragment ecology. In general, populations and communities of species in fragments are hyperdynamic relative to nearby intact forest. Some edge and fragment-isolation effects have declined with a partial recovery of secondary forests around fragments, but other changes, such as altered patterns of tree recruitment, are ongoing. Fragments are highly sensitive to external vicissitudes, and even small changes in local land-management practices may drive fragmented ecosystems in markedly different directions. The effects of fragmentation are likely to interact synergistically with other anthropogenic threats such as logging, hunting, and especially fire, creating an even greater peril for the Amazonian biota.     

Genetic and economic aspects of marker-assisted reduction of redundancy from a wild potato germplasm collection

The wild potato germplasm collection of the series Acaulia, maintained at the Centre for Genetic Resources, The Netherlands, consists of 314 accessions. In previous investigations, 15 potential duplication groups with a total of 36 accessions were identified based on AFLP analysis of a limited sample per accession. In the present study, the potential redundancies, plus one additional accession, were studied with increased sample sizes to examine intra- and inter-accession variation more accurately, with the aim to reduce the size of the collection. No variation was observed within two potential duplication groups, whereas only limited differentiation among accessions was detected within seven groups, resulting in a total of 15 redundant accessions (nearly 5% of the collection). A cluster analysis of all the accessions of the collection showed that these nine groups each had a distinct identity. It was decided to maintain the accessions of the remaining six groups as separate entries based on the large differentiation observed among accessions and the absence of a clear identity. An analysis of molecular variance in the set of 37 accessions showed that 91% of the observed variation could be found among accessions. This variance component appeared unaffected when the set was analysed without the 15 redundant accessions. The invested costs to identify redundancies in the series Acaulia by AFLP analysis are estimated at k 57.3, whereas the savings achieved by reduction of the collection are estimated at k 21.0 per generation. However, a cost-benefit analysis should not only focus on the short-term return of investments, but should also consider the value of newly obtained data and information. These include taxonomic information about accessions, optimised sampling strategies, optimised regeneration procedures, additional data for core collection formation and more efficient utilisation of germplasm.     

Recovery of previously acidified lakes near Coniston,Canada following reductions in atmospheric sulphur and metal emissions

The purpose of the present study was to assess the rate of recovery of acidified lakes located near the town of Coniston following an abrupt reduction in atmospheric SO₂ and metal emissions at the Coniston smelter which closed in 1972. The water chemistry of several lakes was studied over a period of 16 yr (1968–1984). In one extremely acidic lake close to the smelter, the pH increased from 4.05 in 1972 to 5.8 in 1984. Conductivity, as well as concentrations of SO₄, Cu, Ni, Co, Mn, and Zn decreased by 60% to 90% in the lake water during the same period. In another initially less acidic lake nearby, the increase in pH was less dramatic, while the decrease in conductivity, SO₄, and some metals was similar to that of the more acidic lake. Local SO₄ deposition decreased approximately 75 % while Cu and Ni deposition decreased by 90% following closure of the Coniston smelter. These results indicate that even severely acidified lakes can improve within a few years following a substantial reduction in atmospheric S emissions; and that in some regions recovery can occur due to reductions in SO₂ emissions even in the absence of concurrent NO_x control.     

Effects of soil properties and humidity regimes on semi-natural meadow productivity

ABSTRACT

The research has been conducted for four years in five phytocenoses affected by the processes of naturalization. Two of them are located in non-flooded, relatively abandoned meadows and the remaining - flooded meadows in different parts of the Nemunas delta (Western Lithuania). The aim of the research was to estimate the influence of ecological conditions (humidity regimes, soil agrochemical parameters) on semi-natural meadow productivity. Humidity regimes and nitrogen amount in the soil influenced dry matter (DM) yield of meadow phytocesosis. The biggest DM yield (8.64 ± 0.77 t ha^-1) was found in flooded meadow in the central part of the Nemunas delta in Terric Histosol (HSs) soil, which had moderate acidity and was rich in nitrogen. The economic value depended on the prevailing plant species and was the highest in non-flooded meadows. Botanical composition and plant species number depended on agrochemical characteristics of the soil and management activities: the greatest plant species diversity and the best plant population stability were established in flooded meadow in the riverside part of the Nemunas delta behind a levee in soil rich in phosphorus and potassium and low acidity. A similar number of plant species and similar ecological stability parameters were found in non-flooded meadow, whose soil was low in nutrients, but there was intensified farming.