Comparison of the genetic determinism of two key phenological traits,flowering and maturity dates,in three Prunus species: peach,apricot and sweet cherry

The present study investigates the genetic determinism of flowering and maturity dates, two traits highly affected by global climate change. Flowering and maturity dates were evaluated on five progenies from three Prunus species, peach, apricot and sweet cherry, during 3–8 years. Quantitative trait locus (QTL) detection was performed separately for each year and also by integrating data from all years together. High heritability estimates were obtained for flowering and maturity dates. Several QTLs for flowering and maturity dates were highly stable, detected each year of evaluation, suggesting that they were not affected by climatic variations. For flowering date, major QTLs were detected on linkage groups (LG) 4 for apricot and sweet cherry and on LG6 for peach. QTLs were identified on LG2, LG3, LG4 and LG7 for the three species. For maturity date, a major QTL was detected on LG4 in the three species. Using the peach genome sequence data, candidate genes underlying the major QTLs on LG4 and LG6 were investigated and key genes were identified. Our results provide a basis for the identification of genes involved in flowering and maturity dates that could be used to develop cultivar ideotypes adapted to future climatic conditions.     

Community-level flowering phenology and fruit set: Comparative study of 25 woody species in a secondary forest in Japan

We investigated the flowering phenology, pollinator visitation, and fruit set of 25 animal-pollinated woody species in a warm temperate secondary forest in Japan. Various species flowered sequentially from February to October. The principal pollinators were bumblebees, honey-bees, flies and/or beetles and birds; bumblebees and flies/beetles pollinated most trees. The duration of flowering was shorter for species that bloomed in the middle of the season than it was for species that bloomed earlier or later in the season. The timing of flowering was more synchronous within species that had a shorter flowering duration; this was also detected when phylogenetically independent contrasts were calculated. This could be important for the effective pollination of species with a short flowering duration because such species bloom sequentially over a short period of less than 1month around May. Fruit set was related not to pollinator type, sex expression, flowering sequence (in order of the date of peak flowering) or flowering duration, but to the relative abundance of the species in the forest. This correlation was detected for fly- and beetle-pollinated species but not for bumblebee-pollinated species. Thus, relatively rare plant species with opportunistic pollinators might experience limited fruit set because of insufficient pollinator services. Bagging experiments conducted on eight hermaphrodite species revealed that the fruit set of bagged flowers was nearly zero, lower than that of control flowers. These results indicate the importance of pollinators for successful reproduction and thus for the coexistence of plants in this secondary forest.     

Differential responses of mosquito sibling species Anopheles arabiensis and An. quadriannulatusto carbon dioxide, a man or a calf

Field studies on responses of two mosquito sibling species, Anopheles arabiensis Patton and An. quadriannulatus Theobald, to a man, a calf and different release rates of carbon dioxide (man, calf and cow equivalents) were conducted in north-eastern South Africa. Various combinations of baits were compared in two-choice tests, using two mosquito nets, placed 2.5 m apart and 10 cm off the ground. Mosquitoes attracted to the baits were able to enter the nets from below and were collected by means of a suction tube. In a two-choice test between a man and CO₂ (human equivalent, 250 ml/min), 81% of the An. quadriannulatus were caught with CO₂. The reverse was seen for An. arabiensis , where only 20% of the total catch was caught with CO₂ compared to man. High release rates of CO₂ (cow equivalent, 800 ml/min) attracted significantly more An. quadriannulatus than the low release rate (250 ml/min), whereas no significant effect of the release rate of CO₂ on the total catch of An. arabiensis was seen. In the latter species, up to 33% of the attraction of human emanation is attributable to carbon dioxide. Anopheles quadriannulatus was equally attracted to a calf and CO₂ (calf equivalent, 180 ml/min). Catches of other mosquito species showed consistent differences between all treatments which appear to be associated with differences in host-preference, suggesting that the importance of CO₂ in host-seeking behaviour of mosquitoes increases with the degree of zoophily.     

A first mathematical approximation of cerebral cortical responses to cerebello-thalamic signals using a thermodynamic analogue.

A mathematical approximation is developed to predict cerebral cortical responses CTX(t, x, R) at a distance R (R greater than or equal to 0) from a focal point in the cerebral cortex, at a depth x (0 less than or equal to x less than or equal to 500 mu) from the cortical surface and at any time t, to thalamic signals THAL(t) whose amplitudes also vary with time t. The equation is derived from a thermodynamic analogue, which is the time dependent heating of a focus at the surface of a semi-infinite solid.     

Evaluating species nonmonophyly as a trait affecting genetic diversity: a case study of three endangered species of Antirrhinum L. (Scrophulariaceae)

Molecular markers are routinely used to assess levels of diversity within and among populations, particularly with regard to species of conservation concern. However, when interpreting the level and partitioning of diversity observed, an implicit assumption is often made that the populations of the species in question form a monophyletic group. We tested this assumption in three endemics of Antirrhinum (A. charidemi, A. subbaeticum, and A. valentinum) using 79 nuclear [internal transcribed spacer (ITS)] and 85 plastid (psbA-trnH, trnT-trnL, trnK-matK, trnS-trnG) sequences representing multiple accessions of each of 24 Antirrhinum species (single accession of A. cirrhigerum). These species share six life history traits implicated in levels of genetic diversity, and have been the subject of previous population genetic studies. Populations of all three species formed monophyletic groups on ITS analysis. In contrast, none of the three species formed monophyletic groups on plastid sequence analysis: populations of A. charidemi fall in a monophyletic group including one accession of A. mollissimum, populations of A. subbaeticum form a polyphyletic group with plastid sequences shared with A. pulverulentum, and populations of A. valentinum are unresolved within a clade containing six other species. Lack of monophyly using plastid sequences is interpreted as a combination of shared ancestral polymorphism and hybridization in a reticulate evolutionary history of these species. Monophyly in the ITS tree may reflect a more recent sequence homogenization. We draw attention to the evaluation of species monophyly alongside the contribution of other life history traits in the historical interpretation of the level and partitioning of genetic diversity, and its use in recommendations for species conservation programs.     

Development of the first microsatellite markers using high-throughput sequencing for a hexaploid coastal species,Tournefortia argentea L. f. (Boraginaceae)

Molecular Biology Reports - Tournefortia argentea L. f. is a hexaploid shrub or tree species with ecological and evolutionary significances, which forms the fringe of vegetation closest to the sea...     

Regulation of biotechnology in the United States: One and a half years of using the 'coordinated framework'

There are several organizations in the US with responsibilities for regulatory oversight of the planned introduction of recombinant DNA organisms into the environment. Equally, there are many kinds of projects which require assessment. The policies, recommendations and rulings of the various authorities have been integrated into a 'Coordinated Framework' which defines the operation of flexible case-by-case risk assessment. Additions to and revision of the guidelines are being made, a process which will continue in the light of new experience.     

Oxidative,heat and anthelminthic stress responses in four species of Trichinella: comparative study

The aim of this study was to compare levels of stress proteins in four Trichinella species when exposed to different stressors. Heat shock protein (HSP) 60, 70 and 90 responses were evaluated in infective larvae (L(1)) of four classic Trichinella species following exposure to oxidative, anthelminthic and thermal stress. Larvae of T. nativa, T nelsoni, T. pseudospiralis and T. spiralis were exposed to peroxide shock (0.2%, 1%, or 2% H(2)O(2)for 2h), high temperatures (40 degrees C or 45 degrees C for 2h), or 0.1 microg/ml of the benzimidazole anthelminthics: mebendazole (MBZ), albendazole (ALB) or thiabendazole (TBZ) for 4h. Following exposures, the L(1) were tested for induced morphological changes. Those observed were: (i) no change (in all species exposed to 40 degrees C) (ii) aberrant forms (in all species exposed to anthelminthics, in T. nativa, T. nelsoni and T. spiralis exposed to 45 degrees C, and in T. spiralis and T. nelsoni exposed to 0.2% H(2)O(2)) and (iii) severe degradation or death (in T. nativa and T. pseudospiralis exposed to 0.2% H(2)O(2), and in all species at 1% and 2% H(2)O(2)). In Western blot analyses, L(1) proteins were probed with monoclonal antibodies (mAbs) specific for the three HSPs. Greater changes in HSP levels occurred following H(2)O(2) exposure than with other stresses in all Trichinella species, while accumulation of a 50 kDa HSP was only observed in T. spiralis and T. pseudospiralis. Anthelminthic stress only caused decreased HSP levels in T. nativa. Thermal stress caused no significant changes in the HSP response of any species. It is suggested that other stress proteins (e.g., glucose-regulated proteins) may be involved in adaptation to thermal stress.     

25 years of a unique chromosome-breakage system. I. Principal features and comparison to other systems

The principal features of the D. robusta chromosome-breakage system are reviewed and compared to intrinsic chromosome-breakage systems in other Drosophila species, particularly the 'hybrid dysgenesis' systems of D. melanogaster. The data indicate that the D. robusta system is unique in many respects, especially in its combination of a reciprocal cross effect, traceable to its maternal or cytoplasmic inheritance, exclusive susceptibility of the paternal chromosomes, and the randomness of the breaks on the chromosomes.     

The first isolation of ustilaginomycetous anamorphic yeasts,Pseudozyma species,from patients' blood and a description of two new species: P. parantarctica and P. thailandica

The genus Pseudozyma is ustilaginomycetous anamorphic yeasts, and are mainly isolated from plants. We isolated three Pseudozyma strains from the blood of patients in Thailand. While one isolate was identified as P. antarctica by rDNA sequence analysis, the other two were considered to be new species and were named P. parantarctica and P. thailandica. The three isolates proved to be resistant to 5-flucytosine, and P. thailandica was also resistant to fluconazole and itraconazole. As far as we know, this is the first isolation of Pseudozyma strains from humans. The two new species are described.     

Nutrient levels in corn and competing weed species in a first year milpa,Indian church,Belize, C.A.

Summary Grain production in two 1/4 hectare plots gave 2971 and 1380 kg/ha for an average yield of 2175 kg/ha. Average yield for local farmers was 1700 kg/ha. Weed biomass accounted for 50% of total bioomass in the hydric Site 4, but held 64–83% of the total nutrients. In the mesic Site 1, values were 5% and 3–29% respectively.Canna edulis was the most abundant weed species. Soil nutrient levels neither increased or decreased significantly between clearing and harvesting. Any decline in future crop production would be due to increased weed competition and not a decline in soil fertility. Weevil (Sitophilus zeamais) infestation is a serious problem in hybrid corn not encountered with local varieties.     

Improving species distribution models using biotic interactions: a case study of parasites,pollinators and plants

Biotic interactions have been considered as an important factor to be included in species distribution modelling, but little is known about how different types of interaction or different strategies for modelling affect model performance. This study compares different methods for including interspecific interactions in distribution models for bees, their brood parasites, and the plants they pollinate. Host–parasite interactions among bumble bees (genus Bombus: generalist pollinators and brood parasites) and specialist plant–pollinator interactions between Centris bees and Krameria flowers were used as case studies. We used 7 different modelling algorithms available in the BIOMOD R package. For Bombus, the inclusion of interacting species distributions generally increased model predictive accuracy. The improvement was better when the interacting species was included with its raw distribution rather than with its modeled suitability. However, incorporating the distributions of non‐interacting species sometimes resulted in similarly increased model accuracy despite their being no significance of any interaction for the distribution. For the Centris‐Krameria system the best strategy for modelling biotic interactions was to include the interacting species model‐predicted values. However, the results were less consistent than those for Bombus species, and most models including biotic interactions showed no significant improvement over abiotic models. Our results are consistent with previous studies showing that biotic interactions can be important in structuring species distributions at regional scales. However, correlations between species distributions are not necessarily indicative of interactions. Therefore, choosing the correct biotic information, based on biological and ecological knowledge, is critical to improve the accuracy of species distribution models and forecast distribution change.     

Epilepsy in the first 10 years of life: findings of the child health and education study.

OBJECTIVES--To identify children with afebrile seizures in a national cohort, classify the seizures, and document progress in the first 10 years of life. DESIGN--Population based birth cohort study. SETTING--The child health and education study, which includes 16,004 neonatal survivors (98.5% of infants born in the United Kingdom during one week of April 1970). SUBJECTS--14,676 children for whom relevant information was available. MAIN OUTCOME MEASURES--Responses to parental and general practitioner questionnaires and hospital records at 5 and 10 years after birth. RESULTS--84 children (42 boys, 42 girls) had had one or more afebrile seizure (incidence 5.7/1000). 63 children (31 boys, 32 girls) had epilepsy (incidence 4.3/1000). 49 of 55 children had a second seizure within a year of the first. The commonest seizure types were tonic-clonic (42) and complex partial (25). A greater proportion of children with complex partial seizures had recurrences. Children who had infantile spasms or a mixed seizure disorder had a poor outcome. All six children who died had symptomatic seizures in the first year, but seizures were not the direct cause of death. CONCLUSIONS--The results of this study are probably representative of seizure patterns in the general population. Outcome after seizures is determined more by the underlying disease than by the seizures themselves.     

Gas exchange responses of a mangrove species, Avicennia marina, to waterlogged and drained conditions

This study was undertaken in summer on fully expanded leaves of Avicennia marina trees in the Beachwood Mangroves Nature Reserve, Durban,South Africa. Data sets were obtained over 5–7 days of relatively dry conditions and over two periods of 5 days during which the swamp was continuously inundated with dilute seawater (< 150 mol m⁻³NaCl). Gas exchange responses were strongly influenced by photosynthetic photon flux density (PPFD), leaf temperature and leaf to air vapour pressure deficit (Δw). Carbon dioxide exchange was saturated at a PPFD of about 800 μmol m⁻² s⁻¹. Maximal CO₂ exchange rates ranged from 8.5 to 9.9 μmol m⁻² s⁻¹ with no differences between drained and waterlogged conditions. Under drained conditions, leaf conductance,transpiration and internal CO₂ concentrations were generally lower, and water use efficiencies higher, than during waterlogging. Continuous waterlogging for 5 days had no adverse effect on CO₂ exchange. Xylem water potentials ranged from −1.32to −3.53 MPa during drained and from −1.02 to −2.65 Mpa during waterlogged conditions. These results are discussed in relation to anatomical and metabolic adaptations of A. marina to waterlogging stress. This revised version was published online in August 2006 with corrections to the Cover Date.     

Cellular responses of two rapid-cycling Brassica species, B. napus and B. carinata, to seawater salinity

Cellular responses of two rapid-cycling Brassica species. B. napus and B. carinata , to seawater salinity were characterized to determine whether callus showed a tolerance similar to that of whole plants. Callus was initiated from the leaves of 7-day-old seedlings of B. napus and B . carinata and then subcultured with two different levels of seawater salinity (2.3 and 5.2 g l⁻¹ Instant Ocean. Aquarium Systems, Inc. Mentor. OH, USA) for 14 days. Callus growth of both species was reduced by seawater salinity. Based on the percentage of the reduction in the relative fresh weight gain. B. napus was more salt-tolerant than B. carinata . consistent with the response of whole plants of the same species to seawater salinity. Seawater salinity caused changes in the concentrations of Na, K. Ca, Mg and Cl in both B. napus and B. carinata . The growth expressed as the percentage of control was significantly (P = 0.05) positively correlated with the concentration of Ca. and K/Na and Ca/Na ratios. It was also negatively correlated ( P = 0.01) with the concentrations of Na. Cl and Mg. In comparison with B. carinala . the salt-tolerant species, B . napus , showed a small reduction in the concentrations of Ca and K in the salt-stressed plants relative to the control.