Contribution of transpiration to forest ambient vapour based on isotopic measurements

Using a simple isotope mixing model, we evaluated the relative proportion of water vapour generated by plant transpiration and by soil evaporation at two sites in the Amazon basin. Sampling was carried out at two different soil covers (forest and pasture), in a seasonal tropical rainforest at eastern Amazon where major deforestation is the result of land-use change, and compared to a less seasonal central Amazon forest. In both forests, vapour from transpiration was responsible for most, if not all, of the water vapour generated in the forest, while it could not be detected above the grassy pastures. Thus the canopy transpiration may be a major source of water vapour to the forest and perhaps to the atmosphere during the dry season. The results are discussed in relation to predictive models based on net radiation that usually are not able to distinguish between transpiration and evaporation.     

The pollen morphology of Phyllanthus (Euphorbiaceae) section Choretropsis

The pollen grain morphology of the eight South American species of the genus Phyllanthus , subgenus Phyllanthus , section Choretropsis , endemic to Brazil, was investigated using light and scanning electron microscopy. The high homogeneity in pollen shape, as well as aperture number and configuration, allowed the definition of a basic pollen type for this section, viz. prolate spheroidal or subprolate, zonocolporate with 4–5 invaginated colpi, sexine reticulate. Two subtypes have been observed, based on pollen grain apertures and exine sculpture. The first subtype is characterized by straight and narrow colpi provided with costae, lalongate endoapertures and a reticulum of rectilineous muri as in P. choretroides and P. spartioides . The second subtype has wider colpi without costae, circular endoapertures and a reticulum with curvilineous muri as in P. flagelliformis , P. goianensis and P. scoparius , or curvilineous-rectilineous muri as in P. angustissimus , P. gladiatus and P. klotzschianus . It was demonstrated that the pollen shape and the number of colpi varied within and between some of the species. The results suggest that pollen grain morphology, in association with plant architecture and the presence of phylloclades, constitute additional evidence to delimit the species of the section Choretropsis and to further understand their evolutionary origin within the genus Phyllanthus.  © 2004 The Linnean Society of London, Botanical Journal of the Linnean Society , 2004, 144 , 243–250.     

Palynotaxonomy of Brazilian species of Polygala subgenus Hebeclada

This study used pollen morphology to address taxonomic controversies related to several species belonging to subgenus Hebeclada of the genus Polygala (Polygalaceae). According to the last traditionally accepted revision of this subgenus, it comprises 40 species. Nevertheless, a recent taxonomic treatment applying more comprehensive criteria reduced this number to only nine species. Our work focused on 15 traditionally accepted species that occur in Brazil, fourteen of which have been considered as only six species in this recent taxonomic study. Pollen grains from floral buds at pre‐anthesis were collected from herbarium specimens and analysed using both visible light and scanning electron microscopy. Most of the traditionally accepted species were distinguished by different combinations of several pollen‐related features, in particular colpi number (13 or 15), pollen size and shape, and endoaperture type (endocingulate or not) and arrangement (parallel or sinuous). The species accepted in the recent taxonomic treatment could not be discriminated by pollen characters. © 2008 The Linnean Society of London, Botanical Journal of the Linnean Society, 2008, 157 , 609–619.     

Curative Effects of the Antipiroplasms Amicarbalide and Imidocarb on Trypanosoma brucei Infection in Mice*

SYNOPSIS The babesicides imidocarb and amicarbalide, which have structural similarities to the antitrypanosomatid diamidines, proved active against Trypanosoma brucei mouse infections: both cured infections when doses were administered daily for 3 days 24 h post-inoculation (curative dose imidocarb, 10 mg/kg; amicarbalide, 25 mg/kg). Mice were considered cured after survival 30 days longer than untreated infected controls, with no trypanosomes present in blood or cerebrospinal fluid smears. Both agents also cured when administered 48 and 72 h after challenge with T. brucei and prolonged the lives of animals 94 h after challenge. The results are discussed in respect to the potential of these carbanilides and their precursors, the antitumor phthalanilides, as lead compounds in chemotherapy of mammalian trypanosomiases.     

Properties of a resistance-breaking strain of potato virus X

During indexing of a potato germplasm collection from Bolivia, a strain of potato virus X (PVX), X_HB, which failed to cause local lesions in inoculated leaves of Gomphrena globosa was found in 7% of the clones. X_HB was transmitted by inoculation of sap to 56 species from 11 families out of 64 species from 12 families tested. It was best propagated in Nicotiana glutinosa or N. debneyi; Montia perfolia and Petunia hybrida were useful as local lesion hosts. Inoculated leaves of G. globosa plants kept at 10°, 14°, 18°, 22°, or 26 °C after inoculation were always infected symptomlessly. X_HB caused a mild mosaic, systemic chlorotic blotching or symptomless infection in 16 wild potato species and eight Andean potato cultivars, systemic necrotic symptoms in clone A6 and cultivar Mi Peru, and bright yellow leaf markings in cultivar Renacimiento. It caused necrotic local lesions in inoculated leaves of British potato cultivars with the PVX hypersensitivity gene Nb but then invaded the plants systemically without causing further necrosis; with gene Nx systemic invasion occurred but no necrotic symptoms developed. These reactions resemble those of PVX strain group four. X_HB differed from other known strains of PVX in readily infecting PVX-immune clones 44/1016/10, G. 4298.69 and USDA 41956, cultivars Saphir and Saco, and Solanum acaule PI 230554. X_HB had slightly flexuous filamentous particles with a normal length of 516 nm. It was transmitted readily by plant contact and it partially protected G. globosa leaves from infection with X_CP, a group two strain of PVX. Sap from infected N. glutinosa was infective after dilution to 10^--⁶ but not 10^--⁷ after 10 min at 75° but not 80 °C and after 1 yr at 20 °C. X_HB was readily purified from infected N. debneyi leaves by precipitation with polyethylene glycol followed by differential centrifugation. Microprecipitin tests showed that X_HB and X_CP are closely related serologically.     

Diet, prey-size selection and intake rates of Black-tailed Godwits Limosa limosa feeding on mudflats

This paper describes aspects of the winter feeding ecology of Black-tailed Godwits Limosa limosa on an intertidal mudflat in the Tagus estuary, Portugal. Their diet consisted mainly of the bivalve mollusc Scrobicularia plana , which represented 88% of the ingested biomass. The remaining 12% was the worm Nereis diversicolor and, occasionally, the snail Hydrobia ulvae . Ingested Scrobicularia varied between 10 and 20 mm in length, and all size classes of Nereis present in the sediment, except those smaller than 20 mm, were preyed upon. A change in dietary composition occurred over the winter, probably in response to changes in the availability of Nereis and small Scrobicularia . Intake rates averaged 74.9 mg dry weight per minute, which corresponded to a net energy intake of 1.21 kJ per min.     

Terrestrial Activity in Pitheciins (Cacajao,Chiropotes, and Pithecia)

Neotropical monkeys of the genera Cacajao, Chiropotes, and Pithecia (Pitheciidae) are considered to be highly arboreal, spending most of their time feeding and traveling in the upper canopy. Until now, the use of terrestrial substrates has not been analyzed in detail in this group. Here, we review the frequency of terrestrial use among pitheciin taxa to determine the ecological and social conditions that might lead to such behavior. We collated published and unpublished data from 14 taxa in the three genera. Data were gleaned from 53 published studies (including five on multiple pitheciin genera) and personal communications of unpublished data distributed across 31 localities. Terrestrial activity was reported in 61% of Pithecia field studies (11 of 18), in 34% of Chiropotes studies (10 of 29), and 36% of Cacajao studies (4 of 11). Within Pithecia, terrestrial behavior was more frequently reported in smaller species (e.g. P. pithecia) that are vertical clingers and leapers and make extensive use of the understory than in in the larger bodied canopy dwellers of the western Amazon (e.g. P. irrorata). Terrestrial behavior in Pithecia also occurred more frequently and lasted longer than in Cacajao or Chiropotes. An apparent association was found between flooded habitats and terrestrial activity and there is evidence of the development of a “local pattern” of terrestrial use in some populations. Seasonal fruit availability also may stimulate terrestrial behavior. Individuals also descended to the ground when visiting mineral licks, escaping predators, and responding to accidents such as a dropped infant. Overall, the results of this review emphasize that terrestrial use is rare among the pitheciins in general and is usually associated with the exploitation of specific resources or habitat types. Am. J. Primatol. 74:1106‐1127, 2012. © 2012 Wiley Periodicals, Inc.     

Isolated Phosphate-Solubilizing Soil Bacteria Promotes In vitro Growth of Solanum tuberosum L.

The capacity of four bacterial strains isolated from productive soil potato fields to solubilize tricalcium phosphate on Pikovskaya agar or in a liquid medium was evaluated. A bacterial strain was selected to evaluate in vitro capacity of plant-growth promotion on Solanum tuberosum L. culture. Bacterial strain A3 showed the highest value of phosphate solubilization, reaching a 20 mm-diameter halo and a concentration of 350 mg/l on agar and in a liquid medium, respectively. Bacterial strain A3 was identified by 16S rDNA analysis as Bacillus pumilus with 98% identity; therefore, it is the first report for Bacillus pumilus as phosphate solubilizer. Plant-growth promotion assayed by in vitro culture of potato microplants showed that the addition of bacterial strain A3 increased root and stems length after 28 days. It significantly increased stem length by 79.3%, and duplicated the fresh weight of control microplants. In this paper, results reported regarding phosphorus solubilization and growth promotion under in vitro conditions represent a step forward in the use of innocuous bacterial strain biofertilizer on potato field cultures.Key words: Bacillus sp., phosphorus soluble, Pikovskaya agar, potato rhizosphere, plant growth promoting rhizobacteria     

Comparative size,biomass, elemental composition (C,N, H), and energy concentration of caridean shrimp eggs

Summary

In the evolution of decapod crustaceans, interspecific variation in egg size is considered as an important life-history trait that is linked with the duration of embryonic and larval development, the number and type of larval stages, and with juvenile size. Aiming to provide a quantitative characterization of reproductive traits in related decapod taxa differing in lifestyle (freshwater, estuarine, marine) and geographic-climatic distribution (tropical-temperate), we compared size, biomass, and elemental composition of eggs of caridean shrimps from three families: seven species of Palaemonidae (three congeners of Macrobrachium: M. olfersii, M. carcinus, M. acanthurus; four species of Palaemon: P. northropi, P. pandaliformis, P. elegans, P. adspersus), two Atyidae (Potimirim potimirim, Atya scabra), and one Pandalid (Pandalus montagui). Egg size was measured as larger and smaller diameter (D₁ D₂), volume was calculated from D₁ and D₂, and biomass was measured as dry mass (W), carbon (C), nitrogen (N), hydrogen (H), and energy (E, estimated from C) contents. The smallest size and lowest biomass were found in the eggs of two freshwater atyids (both originating from Brazil); the largest size occurred in a marine species, P. montagui (from the North Sea); and intermediate values in freshwater, estuarine, and marine palaemonid species (from Brazil and the Baltic Sea, respectively). Among the Palaemon species, the most limnic (P. pandaliformis) showed a significantly larger egg size and volume (P<0.001) than the estuarine and marine congeners, P. elegans, P. adspersus and P. northropi. This suggests that the generally postulated relationship between egg size and lifestyle (freshwater vs. estuarine or marine) may appear at a generic but not at the family level. On the other hand, individual biomass (in μg or Joules per egg) of early eggs was significantly higher in P. elegans and P. adspersus, indicating interspecific variability in biomass and energy concentration (in μg or Joules per unit volume, mm³). Generally lower biomass concentrations in early eggs of freshwater shrimps may be caused by a higher average water content. Eggs in late embryonic stages were generally larger than earlier eggs of the same species, reflecting an increase in the water content, while an increasing D₁:D₂ quotient indicated an increasingly elongated egg shape. The biomass per egg decreased during embryonic development due to metabolic degradation of organic reserves. As a consequence of inverse ontogenetic changes in size and organic biomass of developing eggs, the mass-specific biomass values (C, N, H in percent of W; E in Joules per mg W) and volume-specific concentrations (μg or Joules per unit volume) decreased. This change was consistently stronger in the C, H, and E contents than in other measures of biomass (W, N). In consequence, the C:N mass ratio also decreased, suggesting that lipid degradation rather than protein utilization was the principal fuel for embryonic development. Our results indicate high intra- (mainly developmental) and interspecific variation in reproductive traits of closely related species. While volume-specific biomass and energy concentrations of early eggs appear to be associated with variation in habitat salinity (freshwater, brackish, marine), individual egg size and biomass may be related more with the climatic-geographic distribution (temperate, tropical) of different taxa.