Enhanced potassium uptake and phosphatidylinositol -phosphate turnover by hypertonic mannitol shock

A hypertonic mannitol shock enhanced K⁺ uptake by Beta vulgaris L. (cv. early flat Egyptian) storage tissue slices and also increased the inositol 1,4,5-trisphosphate [Ins(1,4,5)P₃) content of the slices as well as of Sorghum bicolor L. (cv. Hazera) and Vigna radiata L. (cv. unknown) roots. K⁺ uptake by B. vulgaris slices could be enhanced, in the absence of mannitol, by application of effectors that mimic products of the phosphatidylinositol 4,5-bisphosphate (PIP₂) turnover cycle. Maximal Ins (1,4,5)P₃ content was found 10 min after hypertonic induction and maximal K⁺ uptake was obtained 10 min later. The hypertonic mannitol shock, administered to intact B. vulgaris slices, also enhanced the phosphorylation of a 39 kDa protein in the plasmalemma.     

Adaptive nature of the transition phases in development: the case of Sorghum bicolor

An increase in tolerance to salinity is induced in Sorghum bicolor by exposure to a sublethal concentration of NaCl during early vegetative development. The phase of competence for induction of this response, termed salt adaptation, is well defined in time and it coincides with the emergence of the first adventitious roots. The link between these events was investigated. Competence for salt adaptation varies among genotypes. It is shown that competence is especially high for genotypes in which the link between the seminal root and the shoot is reduced during emergence of the adventitious root. These data relate the capacity for salt adaptation with development in the absence of NaCl, suggesting that: (i) functional integration of the adventitious roots within the whole plant has an adaptive nature in normal development; (ii) salt adaptation results from an integration of the environmental constraint (NaCl) during this developmental readjustment. It is concluded that perturbations generated by emergence of a new organ are the cause of rapid variations in sensitivity required to open a competence window.     

Perturbation in leaves of salt-treated Sorghum: elements for interpretation of the normal development as an adaptive response

Developmental windows are specific periods of sensitivity in which a perturbation may be adaptively integrated. In Sorghum bicolor , two developmental windows which enable adaptive adjustment to salinity (increase in tolerance) have been described during vegetative development. A third developmental window is open during the transition between vegetative and reproductive development. This third developmental window was analysed using morphological markers (specific malformations on leaves), and their relationship with vegetative and reproductive events. A positive link was observed between fertility and malformations on the last leaf. We concluded that this late window enables an adaptive adjustment of reproductive development, counteracting the negative effect of salt adaptation on fertility. Developmental windows open following rapid changes in growth of the different organs. They permit adaptive adjustments to emergence or senescence of various organs. This phenomenon is integrated within normal development, but developmental windows are enlarged for plants exposed to perturbation and for their progeny.     

Valorization of different landrace and commercial sorghum (Sorghum bicolor (L.) Moench) straw varieties by anaerobic digestion

To reduce the impact on the environment and enhance the sustainability of resources, it is necessary to promote and strengthen the use of landrace cultivars that advocate regenerative agriculture. In this study, the growth and development as well as the anaerobic digestion (AD) of six different landrace cultivars, two commercial hybrids cultivars and a public genotype of Sorghum bicolor have been evaluated. The landrace cultivars, in general, presented greater heights, biomass yields and compactness shoots as well as similar or an improvement in grain production compare to the commercial varieties. The AD of the different sorghum straws was performed in batch mode at mesophilic temperature (35°C). The landrace cultivar Zahina (ZH) obtained the highest final methane yield (413 ± 79 NL CH₄ kg⁻¹ VS, volatile solids) but the landrace cultivars Zahina gigante (ZHG) and Trigomillo (TG) were the ones that obtained the highest methane per biomass production (13.7 and 12.7 NL CH₄ shoot unit⁻¹, respectively). By contrast, the commercial varieties were the ones that obtained the lowest methane yields. Two mathematical models, first-order kinetics and the Transference Function model, were used to fit the experimental data with the aim of describing and simulating the anaerobic biodegradation of these S. bicolor straw varieties and obtaining the kinetic constants. Both models allowed for adequately fitting the experimental results of methane production with time. In particular, the fastest biomethanization occurred using the commercial variety PR88Y20 (PR88) (specific rate constant k = 0.148 ± 0.008 days⁻¹), while the slowest one was obtained from Panizo (PAN) variety (k = 0.064 ± 0.005 days⁻¹). In addition, the highest values of the maximum methane production rate, R_m, were attained for the varieties ZH and PR88, which were 87.1% and 71.3% higher than that achieved for the PAN variety, which exhibited the lowest value.     

Humoral immunocompetence correlates with date of egg-laying and reflects work load in female tree swallows

Because quality differences between individuals affect fitness,much research has attempted, with limited success, to relatephysiological condition (e.g., body reserves), to differencesin life history between individuals. Recently, it has beensuggested that immunocompetence may reflect condition, andit thus may mediate variation in individual quality and reproductiveperformance and, ultimately, fitness. We measured humoral immunocompetence(HIC) by immunizing female tree swallows with a harmless antigenand measured the specific antibody responses in a novel enzyme-linked immunosorbent assay developed for passerine birds. HIC was stronglycorrelated with egg-laying date, an important determinant ofreproductive success in female tree swallows. We also investigatedthe effect of increased workload on HIC by manipulating femaleflight costs by clipping flight feathers. Clipped females hadlower HIC than nonclipped females. These data suggest that HICis a measure that may reflect phenotypic quality and also appearsto be sensitive to increased workload in female tree swallows.     

Effect of salinity,temperature and hypersaline conditions on the seed germination in Limonium mansanetianum an endemic and threatened Mediterranean species

Abstract

Limonium mansanetianum is catalogued as critically threatened (CR) species and it is included in Valencian Catalogue of Threatened Plant Species. Limonium mansanetianum is a gypsicolous species, which only lives in a restricted area to south-centre of Valencia province (Spain). The species is a low-branched woody shrub with summer flowering. The influence of incubation temperature (10°, 15°, 20° and 25°/20?°C) and salinity (0%–3.0% NaCl) on seed germination of L. mansanetianum was studied. Best seed germination was obtained in distilled water controls. Seed germination decreased with an increase in salinity and few seeds germinated at 2.5% and 3.0% NaCl. Optimal temperature regime for germination was 15?°C where germination in 0.5% and 1.0% NaCl was not affected. Recovery and hypersaline conditions experiments showed that L. mansanetianum seeds displayed a greater tolerance to high salinity and temperature stress before germination.     

The Assembly of an Island Fauna by Natural Invasion: Sources and Temporal Patterns in the Avian Colonization of Barbados

By virtue of their isolation and depauperate faunas, oceanic islands offer unique opportunities to characterize the historical development of ecological communities derived from both natural and anthropogenic invasions. Barbados, an outlying island in the Lesser Antilles, was formed approximately 700,000 YBP by tectonic uplift and was then colonized by birds via natural invasion from the much older volcanic islands in the main Lesser Antillean arc. We investigated the timing and sources of the avian invasion of Barbados by determining levels of mitochondrial DNA (mtDNA) divergence between populations of eight bird species from Barbados and those on the nearby putative source islands of St. Lucia and St. Vincent. Although all Barbados populations appeared to be young relative to the geological age of the island, we found differences among species in their inferred times of colonization and we identified at least two sources of immigrants to Barbados. In contrast to these historical differences across species and populations, our characterization of the mitochondrial genotypes of 231 individual birds suggests that each island population represents the descendants of a single founding maternal lineage. Considered in concert, the results of this molecular survey indicate that the Barbados bird community is composed of species with different invasion histories, which in turn suggests that the island's community composition has changed repeatedly over its 700,000 year history.     

Food Sharing in Pied Bare-Faced Tamarins (Saguinus bicolor bicolor): Development and Individual Differences

We investigated food sharing behavior in 5 litters of pied bare-faced tamarins (Saguinus bicolor bicolor)—8 infants, from 3 families—from 5 to 26 weeks of age. The frequency of sharing by parents in response to infant begging increased steadily from the age of 5 weeks to 16 weeks, and then declined. Offering of food by adults without prior infant begging occurred at very low frequencies throughout observations (1.5% of total items transferred). On average, infants received approximately equal amounts of food from transfers from others and by self feeding until about 20 weeks, after which self feeding began to predominate. Begging success—the proportion of infant begs which resulted in food sharing—remained relatively constant over time, at 60–70%. Overall, therefore, the frequency of food sharing seemed to be governed by changes in infant rather than adult behavior. There were individual differences between adults in their response to infant begging, but two of three fathers transferred significantly more food to infants than mothers did. The results of this study emphasize the existence of specific and individual differences in food-sharing behavior, which must be taken into account in explaining its importance in the reproductive strategies of the Callitrichidae.     

Revision of the genus Fascicularia Mez (Bromeliaceae)

The genus Fascicularia Mez is revised as part of a study of the Bromeliaceae for the Flora de Chile. Morphological and anatomical investigation of herbarium and living material from cultivation as well as DNA-studies (RAPDs) in cultivated material has led us to conclude that Fascicularia bicolor (Ruiz & Pav.) Mez, the only one species in the genus, comprises two subspecies which are distinguished by their leaf anatomy and morphology.