The influence of vegetation pattern on the productivity,diversity and stability of vegetation: The case of `brousse tigrée' in the Sahel

Sample sites of `brousse tigrée' and related vegetation types are described for Mali and Niger. Species composition and physical structure of the herbaceous layer as well as woody plant population were recorded at all sites together with data on soils and natural resource management. Herbage yield was measured whereas foliage yield and wood mass were calculated using allometry equation calibrated for each species. `Brousse tigrée' is characterized by the regularly alternating bare-soil stripes with dense linear thickets arranged perpendicularly to the slope. There was no clear superiority in total plant production of `brousse tigrée' when compared to neighbouring site with diffuse vegetation. However, the pattern of `brousse tigrée' tended to favour woody plant yield to the detriment of herbage yield. The number of herbaceous species recorded per site (22–26) was slightly above Sahelian vegetation average despite low number of species per 1-m² quadrat (6–9), bare soil excluded. This species richness reflects the diversity in edaphic niches resulting from the redistribution and local concentration of water resources and shade. The high spatial heterogeneity and species richness of the herbaceous layer in `brousse tigrée' did not attenuate the interannual variation in herbage yield despite low yields. Except for the herb layer, little evidence was found of grazing influence on the vegetation structure and yield a few hundred metres away from livestock concentration points. On the other hand, the clearing of thickets for cropping led to severe soil erosion which threaten the resilience of `brousse tigrée'. These observations and the well-defined climatic, soiland topographic situations under which the `brousse tigrée' occurs invalidate the hypothesis of an anthropic origin of that vegetationpattern.     

Parameters of glucose and lipid metabolism in the male Göttingen minipig: influence of age, body weight, and breeding family

The pig is useful as a model for human physiology and pathophysiology and could be an important supplement to the many available rodent models of diabetes mellitus. Due to their small size, G?ttingen minipigs are especially suitable for long-term studies. The aim of the study reported here was to establish reference values for a range of glucose and lipid homeostasis parameters of interest that could be used to identify possible diabetes-prone male G?ttingen minipig individuals, families, or age groups. Plasma samples from nonfed animals were analyzed for glucose, leptin, fructosamine, insulin, C-peptide, triglyceride, free fatty acids, and total cholesterol values. Breeding family had significant effects only on plasma triglyceride concentrations (P < 0.001). Plasma concentrations of glucose (P = 0.012), fructosamine (P < 0.001) and triglycerides (P < 0.001) increased significantly with age, whereas total cholesterol concentration decreased significantly (P = 0.001) with age. Age did not influence other parameters. In conclusion, glycemia and insulinemia increased with age and body weight, possibly indicating a small deterioration in insulin sensitivity with age. It is, therefore, hypothesized that older, compared to younger animals may be more useful in the development of a model of type-2 diabetes mellitus. Furthermore, on the basis of decrease in cholesterol concentration with age, animals fed ad libitum with possibly a high calorie diet might be even more useful in the development of a type-2 diabetes mellitus model.     

The influence of androgenic steroid hormones on female aggression in ‘atypical’ mammals

Dimorphism on dominance and agonistic behaviour in mammals tends to be strongly biased toward males. In this review, we focus on a select few species of mammals in which females are as or more aggressive than males, and/or are dominant to males, and explore the role of androgenic hormones in mediating this important difference. While the data are not as clear-cut as those published on traditional laboratory mammals, our review highlights important endocrine substrates for both organizational and activational influences of steroids on female aggressive behaviour. We highlight areas in which further observations and experiments are crucial, especially the potential facilitative effects of androgens on female aggression. Finally, new and innovative techniques, including molecular genetics and receptor pharmacology, portend important insights into the ways in which androgenic hormones regulate aggressive behaviour in ‘atypical’ female mammals.     

The influence of different yeasts on the fermentation,composition and sensory quality of cachaça

Summary Cachaça (sugarcane wine) was produced using different yeast strains, six being strains of Saccharomyces cerevisiae and one each of Candida apicola, Hanseniaspora occidentalis, Pichia subpelliculosa and Schizosaccharomyces pombe. The ethanol yields (%) of the non-Saccharomyces strains were similar to those of the Saccharomyces strains. The following determinations were carried out on the cachaça: acetaldehyde, ethyl acetate, propanol, isobutyl alcohol, isoamyl alcohol, volatile acidity. The cachaças showed variations in the levels of secondary compounds, but these variations did not result in differences (P ≤ 0.05) in the sensory attributes of aroma and flavour and overall impression. Of the volatile compounds quantified in the cachaças, only propanol showed a positive correlation (P ≤ 0.05) with the flavour attributes and overall impression. The S. pombe strain was considered inadequate for the production of cachaça. The cachaças were classified into five groups in an exploratory Hierarchical Cluster Analysis as a function of the volatile compounds. Principal Component Analysis showed that 93% of the variation (PC 1) occurred among the samples, and was explained by the individual volatile compounds and the total secondary compounds, with the exception of isoamyl alcohol only 7% (PC 2) was associated with the volatile acidity. The negative correlations shown between the volatile compounds of the cachaças and the ethanol content of the sugarcane wine, with the exception of acetaldehyde, showed that the variation in ethanol content of the sugarcane wine is an important factor for standardization of the ethanol/volatiles ratio and the beverage quality.     

The influence of spin-labeled fluorene compounds on the assembly and toxicity of the aβ peptide

Background

The deposition and oligomerization of amyloid β (Aβ) peptide plays a key role in the pathogenesis of Alzheimer''s disease (AD). Aβ peptide arises from cleavage of the membrane-associated domain of the amyloid precursor protein (APP) by β and γ secretases. Several lines of evidence point to the soluble Aβ oligomer (AβO) as the primary neurotoxic species in the etiology of AD. Recently, we have demonstrated that a class of fluorene molecules specifically disrupts the AβO species.

Methodology/Principal Findings

To achieve a better understanding of the mechanism of action of this disruptive ability, we extend the application of electron paramagnetic resonance (EPR) spectroscopy of site-directed spin labels in the Aβ peptide to investigate the binding and influence of fluorene compounds on AβO structure and dynamics. In addition, we have synthesized a spin-labeled fluorene (SLF) containing a pyrroline nitroxide group that provides both increased cell protection against AβO toxicity and a route to directly observe the binding of the fluorene to the AβO assembly. We also evaluate the ability of fluorenes to target multiple pathological processes involved in the neurodegenerative cascade, such as their ability to block AβO toxicity, scavenge free radicals and diminish the formation of intracellular AβO species.

Conclusions

Fluorene modified with pyrroline nitroxide may be especially useful in counteracting Aβ peptide toxicity, because they posses both antioxidant properties and the ability to disrupt AβO species.     

The role of Schmidt ‘Antonovka’ in apple scab resistance breeding

??Antonovka?? has long been recognised as a major source of scab (Venturia inaequalis) resistance useful for apple breeding worldwide. Both major gene resistances in the form of the Rvi10 and Rvi17 and quantitative resistance, collectively identified as VA, have been identified in different accessions of ??Antonovka??. Most of the ??Antonovka?? scab resistance used in apple-breeding programmes around the world can be traced back to Schmidt ??Antonovka?? and predominantly its B VIII progenies 33,25 (PI 172623), 34,6 (PI 172633), 33,8 (PI 172612) and 34,5 (PI 172632). Using genetic profile reconstruction, we have identified ??common ??Antonovka?? ?? as the progenitor of the B VIII family, which is consistent with it having been a commercial cultivar in Poland and the single source of scab resistance used by Dr. Martin Schmidt. The major ??Antonovka?? scab resistance genes mapped to date are located either very close to Rvi6, or about 20?C25?cM above it, but their identities need further elucidation. The presence of the 139?bp allele of the CH-Vf1 microsatellite marker known to be associated with Rvi17 (Va1) in most of the ??Antonovka?? germplasm used in breeding suggests that it plays a central role in the resistance. The nature and the genetic relationships of the scab resistance in these accessions as well as a number of apple cultivars derived from ??Antonovka??, such as, ??Freedom??, ??Burgundy?? and ??Angold??, are discussed. The parentage of ??Reglindis?? is unclear, but the cultivar commercialised as ??Reglindis?? was confirmed to be an Rvi6 cultivar.     

The three C's — competition,coexistence and coevolution — and their impact on the breeding of forage crop mixtures

Summary The role of competition, coexistence and co-evolution in the formation of plant communities is discussed, particularly in relation to the breeding of improved grass/legume mixtures. Competition occurs whenever the demand for a particular resource outstrips supply, with the pressures generated within a species expected to exceed those between species. These pressures must be withstood before populations can coexist within a community. This is accomplished by a process of niche diversification, arising from temporal or spatial differences between the populations, that enables them to draw on resources not readily available to their competitors. Coexistence is crucial to the success of any breeding programme designed to raise the productivity of grass/ legume pastures, because it enables components to adapt not only to the environment which they share, but also to each other. A strategy that improves the general ecological combining ability of one or both components by a process of recurrent or reciprocal recurrent unilateral adaptation may prove successful, particularly if existing niche differences are increased thereby. Although both processes may give rise to populations which have apparently coevolved, only those resulting from reciprocal recurrent selection will meet the criteria of specificity and reciprocity.     

The influence of road salts on the salinity and the meromictic stability of Lake Svinsjøen,southeastern Norway

Primarily as a result of road salting, the water masses ofLake Svinsjøen, a small meromictic lake in southeasternNorway, have been subject to great changes in salinity duringthe period 1947–1995. The greatest change in saltconcentration has occurred in the upper part of themonimolimnion (depth 10–15 m) where mean conductivityincreased 104.2 per cent, from 143 to 292 S cm^–1. Inthe upper mixolimnion (depth 0-5 m), mean conductivity rosefrom 130 to 238 S cm^–1 during the same period. Theions responsible for the salinity changes were Na⁺ andCl^– from de-icing salts, and Ca²⁺ and Cl^– fromsalts used to keep down dust from roads. Further sources ofCa²⁺ are the road asphalt and increased weathering andleaching of the lime-rich rocks caused by acid precipitation,the main source of the additional inputs of SO tothe lake. The salinity changes caused major changes inmeromictic stability, S . In the period1947-1966, S increased by 24 g cm cm^–2,and the maximum level of meromictic stability, 125 gcm^–2, was found in 1966. As a result of higher rate ofsalt accumulation in the upper part of the monimolimnion andin the mixolimnion, S decreased by 30 g cmcm^–2 during the period 1966-1991, and a simultaneousrise in the chemocline took place. In the period 1991-1995 anadditional decrease of 26 g cm cm^–2 occurred. Continuedectogenic inputs of salts through processes typical of thetime period investigated will in future further weaken thelake's meromictic stability, and may cause the demise ofmeromixis in Lake Svinsjøen, a development which may haveimportant implications for primary productivity of thelake.     

The influence of the reference electrode location on the M−wave characteristics in the quadriceps

IntroductionIn the compound muscle action potential (M wave) recorded using the belly-tendon configuration, the contribution of the tendon electrode is assumed to be negligible compared to the belly electrode. We tested this assumption by placing the reference electrode at a distant (contralateral) site, which allowed separate recording of the belly and tendon contributions.MethodsM waves were recorded at multiple selected sites over the right quadriceps heads and lower leg using two different locations for the reference electrode: the ipsilateral (right) and contralateral (left) patellar tendon. The general parameters of the M wave (amplitude, area, duration, latency, and frequency) were measured.Results(1) The tendon potential had a small amplitude (<30%) compared to the belly potential; (2) Changing the reference electrode from the ipsilateral to the contralateral patella produced moderate changes in the M wave recorded over the innervation zone, these changes affecting significantly the amplitude of the M−wave second phase (p = 0.006); (3) Using the contralateral reference system allowed recording of short-latency components occurring immediately after the stimulus artefact, which had the same latency and amplitude (p = 0.18 and 0.25, respectively) at all recording sites over the leg.ConclusionsThe potential recorded at the “tendon” site after femoral nerve stimulation is small (compared to the belly potential), but not negligible, and makes a significant contribution to the second phase of belly-tendon M wave. Adopting a distant (contralateral) reference allowed recording of far-field components that may aid in the understanding of the electrical formation of the M wave.     

How does parental role influence the activity and movements of breeding wolves?

We studied the activity and movements of a male and a female wolf during breeding in the Bieszczady Mountains, Poland. The female was less active and mobile and on average closer to the den than the male. The male was less active and mobile when the pack size was seven compared to a year when the pack consisted only of the breeding pair. We conclude that the roles played by breeding males and females rearing pups influence their activity, and that breeding males in larger packs move less during the nursing period because of help by other pack members.     

A loss of heterozygosity,a loss in competition? The effects of inbreeding,pre‐ and postnatal conditions on nestling development

The early developmental trajectory is affected by genetic and environmental factors that co‐depend and interact often in a complex way. In order to distinguish their respective roles, we used canaries (Serinus canaria) of different genetic backgrounds (inbred and outbred birds). An artificial size hierarchy was created to provoke within‐nest competition, manipulating postnatal conditions. To this end, inbred birds were weight‐matched with outbred birds into duos, and each nest contained one duo of size‐advantaged, and one duo of size‐disadvantaged inbred and outbred nestlings. Prenatal (maternal) effects were taken into account also, enabling us to study the separate as well as the interactive effects of inbreeding, pre‐ and postnatal conditions on nestling development. We find that postnatal conditions were the most important determinant of early growth, with size‐advantaged nestlings growing faster and obtaining larger size/body mass at fledging in comparison with size‐disadvantaged nestlings. Prenatal conditions were important too, with birds that hatched from eggs that were laid late in the laying order obtaining a larger size at fledging than those hatched from early laid eggs. Inbreeding inhibited growth, but surprisingly this did not depend on (dis)advantageous pre‐ or postnatal conditions. Our findings imply that inbred individuals lose when they are in direct competition with same‐sized outbred individuals regardless of the rearing conditions, and we thus propose that reduced competitiveness is one of the driving forces of inbreeding depression.     

‘Good-genes’ and ‘compatible-genes’ effects in an Alpine whitefish and the information content of breeding tubercles over the course of the spawning season

Some models of sexual selection predict that individuals vary in their genetic quality and reveal some of this variation in their secondary sexual characteristics. Alpine whitefish (Coregonus sp.) develop breeding tubercles shortly before their spawning season. These tubercles are epidermal structures that are distributed regularly along the body sides of both males and females. There is still much unexplained variation in the size of breeding tubercles within both sexes and with much overlap between the sexes. It has been suggested that breeding tubercles function to maintain body contact between the mating partners during spawning, act as weapons for defence of spawning territories, or are sexual signals that reveal aspects of genetic quality. We took two samples of whitefish from their spawning place, one at the beginning and one around the peak of spawning season. We found that females have on average smaller breeding tubercles than males, and that tubercle size partly reveals the stage of gonad maturation. Two independent full-factorial breeding experiments revealed that embryo mortality was significantly influenced by male and female effects. This finding demonstrates that the males differed in their genetic quality (because offspring get nothing but genes from their fathers). Tubercle size was negatively linked to some aspects of embryo mortality in the first breeding experiment but not significantly so in the second. This lack of consistency adds to inconsistent results that were reported before and suggests that (i) some aspects of genetic quality are not revealed in breeding tubercles while others are, or (ii) individuals vary in their signaling strategies and the information content of breeding tubercles is not always reliable. Moreover, the fact that female whitefish have breeding tubercles of significant size while males seem to have few reasons to be choosy suggests that the tubercles might also serve some functions that are not linked to sexual signaling.     

‘Good-genes’ and ‘compatible-genes’ effects in an Alpine whitefish and the information content of breeding tubercles over the course of the spawning season

Abies ziyuanensis is a highly endangered fir species endemic to South China. Unlike other Abies species that are distributed in areas with cold climates, A. ziyuanensis is restricted to several isolated island-like localities at subtropical mountains. In this study, we used dominant amplified fragment length polymorphism (AFLP) and co-dominant simple sequence repeats (SSR) markers to infer the genetic structure of A. ziyuanensis. Seven populations consisting of 139 individuals were sampled across their whole distribution. A. ziyuanenesis has a relatively low level of genetic variation, with a mean genetic diversity per population (He) of 0.136 (AFLP) and 0.337 (SSR), which is lower than that of other reported endemic species based on the same kind of marker. We observed high population differentiation, with Gst = 0.482 (AFLP) and Fst = 0.250 (SSR), among the seven populations. AMOVA also detected significant differentiation among populations (Φst (AFLP) = 0.550 and Φst (SSR) = 0.289) and among regions (Φct (AFLP) = 0.139 and Φct (SSR) = 0.135) in both marker types. Both ongoing evolutionary forces (e.g., genetic drift resulting from small population size) and historical events (e.g., population contraction and fragmentation during and after the Quaternary glacial cycles) may have contributed to the genetic structure in A. ziyuanensis.     

The influence of varying illumination on steroid 5α-reductase activity and gonadotropin levels in the rat

The influence of varying illumination on rat hypothalamic, pituitary and prostatic steroid 5α-reductase (SR), body and prostatic weights and plasma FSH, LH and PRL levels was studied. Male rats weighing 50–60 g on arrival were divided as follows: controls (C) received 14 hours of daylight and 10 hours of darkness (14:10), constant light (CL) (24:0), and constant dark (CD) (0:24). After one month the animals were weighed, killed and the following tissues removed for analysis: prostate, hypothalamus, pituitary and blood. Prostates were weighed. Plasma concentrations of LH, FSH and PRL were determined by radioimmunoassay. Other tissues were analyzed for SR. CD animals gained less weight and had less heavy prostates/ 100 g body weight than either C or CL animals. Prostatic and hypothalamic SR activities were reduced following CD, while the pituitary enzyme was unaffected. Gonadotropin levels were unchanged in the CD group. Neither body nor prostatic weights were affected in CL treated animals. Prostatic SR activity increased following CL, while hypothalamic and pituitary enzymes remained unchanged. Plasma LH values were reduced in the CL group. FSH and PRL concentrations did not differ from controls. The prostate appeared most responsive to environmental lighting. It is suggested that observed changes in target organ (prostate) growth due to ambient lighting conditions are mediated via changes in SR.     

The influence of β-glucan on the growth and cell wall architecture of Aspergillus spp

β-1,3-glucan is a major component of fungal cell walls with various biological activities, including effects on the production of inflammatory mediators in vivo and in vitro. However, few reports have examined its influence on the fungal cell itself. In this study, the influences of β-1,3-glucan on the growth and cell wall structure of fungi was examined. Aspergillus fumigatus was cultured with a synthetic medium, C-limiting medium, in the presence or absence of β-1,3-glucan. Hyphal growth was promoted in liquid and solid-cultures by adding β-1,3-glucan. Glucose and dextran did not induce growth. The influence on cell wall structure of the β-glucan-added cultures was examined by enzymolysis and NMR spectroscopy and the amount of β-1,3-glucan found to be changed. β-1,3-glucan has been widely detected in the environment. In this study, it was demonstrated that β-1,3-glucan causes promotion of the growth, and a change in the cell wall architecture, of Aspergillus. Unregulated distribution of β-1,3-glucan would be strongly related to the incidence of infectious diseases and allergy caused by Aspergillus spp.     

The growth of follicles in the rat ovary under the influence of Busulphan and Endoxan®

Summary Busulphan and Endoxan^® inhibit the normal course of ovarian follicular growth. Older secondary as well as all antral follicles perish within a very short time.Growing follicles, which at the beginning of the experiment exhibited only one layer, remained intact and single-layered during the entire duration of the experiment. The oocytes, however, continue growing, and the cytoplasmic structures, which are characteristic of older growing follicles, develop in them as well as in the follicle cells. Even a theca formation develops.In some of the growing follicles which have remained single-layered, after 10 days of Busulphan administration, some liquor folliculi is produced and accumulates in a fissure-shaped antrum between the zona pellucida and the follicular epithelium.     

The play of ‘dirty politics’: ordinary ethics and the evidence of experience on the workfloor in New Delhi,India

This article explores the tensed sociality amongst precariously employed service economy workers in the retail outlets of a prominent eyewear company in New Delhi, India. The bickering staff label the ongoing interpersonal strife ‘dirty politics’. Linked to this are their confident assertions that, in fact, all politics is dirty, and dirty politics is the only type of politics possible – rejecting formal party politics and labour unions as morally vacuous and motivated by utilitarian individualism. Engaging with the anthropology of ordinary ethics, the article demonstrates how the affectively charged experience and talk of petty politicking on the neoliberal workfloor provides critical ‘evidence’ that ‘confirms’ such a politico-ethical view.     

The impact of the ‘New Zealand flatworm’, Arthurdendyus triangulatus, on earthworm populations in the field

The ‘New Zealand flatworm’, Arthurdendyus triangulatus, is a native of the South Island of New Zealand, which has established in the UK, Ireland and the Faroe Islands. In its introduced range, it is a predator of lumbricid earthworms. To assess the impact of A. triangulatus on earthworm species, flatworm distributions were manipulated into ‘high’, control and ‘low’ densities within a replicated field experiment. Earthworm biomass in the ‘high’ flatworm density treatment was significantly lower than the control or ‘low’ treatments. This was due to a reduction in the anecic species Lumbricus terrestris and, to a lesser extent, Aporrectodea longa. There was little evidence of negative effects on other earthworm species, with even a weakly positive relationship between flatworm density and epigeic biomass. Principal components analysis showed a clear separation of anecic species from A. triangulatus, but the epigeic species Lumbricus festivus and Lumbricus rubellus grouped with A. triangulatus, suggesting that they could be benefitting from reduced intraguild competition. Flatworm densities of 0.8 per m², comparable to natural infestations in grassland, were predicted to give a reduction in total earthworm biomass of c. 20 %. The bulk of this was comprised of a reduction in anecic species biomass. In particular, it is considered that A. triangulatus poses a serious risk to L. terrestris populations, with implications for soil functioning and indigenous earthworm-feeding wildlife.