Landscape structure shapes activity levels and composition of aerial insectivorous bats at different spatial scales

Biodiversity and Conservation - Tropical forests are being lost and modified at an unprecedented rate, with extant biodiversity increasingly restricted to human-modified landscapes. Resulting...     

Evaluation of filamentous fungi and inducers for the production of endo-polygalacturonase by solid state fermentation

Aspergillus oryzae CCT 3940, Aspergillus awamori NRRL 3112 and a Trichoderma sp.) were compared for their capacity to produce endo-polygalacturonase (endo-PG) in solid state fermentation. Maximum pectinolytic activity was reached in 72 h of growth, the best two fungal strains being A. niger T0005007-2 and A. oryzae CCT 3940. Three types of commercial purified pectin and four of unprocessed pectin (tangerine, orange, Tahiti lime and sweet lime rind) were used to assess the effect of pectin on the production of endo-PG by A. niger T0005007-2. Maximum pectinolytic activity was achieved using 6 and 10% (w/w) of purified pectin as inducer. Depending on the origin of the commercial pectin used as inducer, maximum endo-PG levels varied from 223 to 876 units per gram of dry medium (one endo-PG unit (U) was defined as the quantity of enzyme which caused a reduction in viscosity of 50% in a 1% w/v solution of pectin in 30 min), indicating that care should be taken when choosing this component of the medium. When the crude pectins were used as inducers at the same concentration as purified pectin, maximum endo-PG activities were 250-300 units/g. However, by increasing the amount of Tahiti lime rind to 50% (w/w) maximum endo-PG was 919 U/g, thus opening up the possibility of a low cost medium for endo-PG production.     

Plasmodium yoelii: semiquantitative analyses of circumsporozoite protein gene expression during the sporogonic development of P. y. yoelii and P. y. nigeriensis in the mosquito vector Anopheles stephensi

Malaria infection in the mosquito vector can be modulated by the vertebrate host, mosquito factors, and interactions between different parasite populations. Modulation of parasite development can be assessed through the study of gene expression. The present report describes a specific, sensitive, and nonradioactive method that permits assessment of parasite load and quantification of circumsporozoite protein gene expression during the sporogonic stages of Plasmodium yoelii yoelii and P. y. nigeriensis. A decrease in parasite load was observed when comparing DNA of oocysts on day 7 postinfection with that of oocysts and sporozoites on day 19. On day 7, parasites (oocysts) showed a marked increase of circumsporozoite protein expression when compared with that (sporozoites and oocysts) on day 19. The method developed in this work can be a valuable tool to understand parasite interaction mechanisms that are involved in mosquito malaria infections.     

Trypanocidal activity of a new pterocarpan and other secondary metabolites of plants from Northeastern Brazil flora

Two hundred fifteen compounds isolated from plants of Northeastern Brazil flora have been assayed against epimastigote forms of Trypanosoma cruzi, using the tetrazolium salt MTT as an alternative method. Eight compounds belonging to four different species: Harpalyce brasiliana (Fabaceae), Acnistus arborescens and Physalis angulata (Solanaceae), and Cordia globosa (Boraginaceae) showed significant activity. Among them, a novel and a known pterocarpan, a chalcone, four withasteroids, and a meroterpene benzoquinone were the represented chemical classes.     

Selection of Pseudomonas for industrial textile dyes decolourization

Pigment is the first contaminant to be recognised in bodies of water and wastewater. Besides the aesthetic problem, dyes obstruct light and reduce oxygen mass transfer. This paper describes the selection of Pseudomonas strains with the ability to remove colour from textile industrial dyes. Four Pseudomonas species were tested against 14 commercial industrial dyes. Pseudomonas cepacia exhibited no growth at all on plates containing dyes (1 g l^?1), whereas Pseudomonas aeruginosa, Pseudomonas oleovorans and Pseudomonas putida exhibited considerable growth. Decolourization in a liquid culture revealed that P. oleovorans is more viable for decolourizing textile dyes, as it achieved over 80% colour removal for two of the 14 dyes studied; it also proved to be more tolerant to high dye concentrations.     

Effects of photoperiod on gluconeogenic activity and total lipid concentration in organs of crabs, Neohelice granulata, challenged by salinity changes

Abstract. This study assessed the effects of long (LD) or short (SD) days on the conversion of [¹⁴C]-glycerol to [¹⁴C]-glucose and total lipid concentration in organs of the crab Neohelice granulata challenged by a change in external salinity. In the 20‰-acclimated crabs, no difference was found in the concentration of total lipids in the muscle, hepatopancreas, gills, or hemolymph between crabs acclimated to SD or LD. In SD crabs, the total lipid levels in the anterior and posterior gills did not decrease during an osmotic challenge. Only in the posterior gills did the total lipid levels decrease during acclimation to the 34‰ medium in LD animals. The total lipid concentration in the hemolymph decreased after 1 d of osmotic stress in SD, and increased in the hepatopancreas. In LD crabs, the lipid contents decreased gradually in muscle, and in the hepatopancreas on day 3 after transfer to 34‰ medium. In 20‰-acclimated crabs, the gluconeogenesis activity in both sets of gills was higher in LD than in SD animals. The gluconeogenesis capacity decreased in both sets of gills on the first day of osmotic challenge in SD, and in the posterior gills on the third day in LD crabs. These results suggest that in organs of N. granulata , photoperiod affects the metabolic adjustments to an osmotic challenge.     

Dynamics of biochemical and morphophysiological changes during zygotic embryogenesis in <Emphasis Type="Italic">Acca sellowiana</Emphasis> (Berg.) Burr.

Acca sellowiana (Berg.) Burr. is a native Myrtaceae from southern Brazil and Uruguay, now the subject of a domestication and breeding program. Biotechnological tools have been used to assist in this program. The establishment of a reliable protocol of somatic embryogenesis has been pursued, with a view to capturing and fixing genetic gains. The rationale behind this work relies on the fact that deepening comprehension of the general metabolism of zygotic embryogenesis may certainly improve the protocol for somatic embryogenesis. Thus, in the present work we studied the accumulation of protein, total sugars, starch, amino acids, polyamines (PAs), IAA and ABA, in different stages of A. sellowiana zygotic embryogenesis. Starch is the predominant storage compound during zygotic embryo development. Increased synthesis of amino acids in the cotyledonary stage, mainly of asparagine, was observed throughout development. Total free PAs showed increased synthesis, whereas total conjugated PAs were mainly observed in the early developmental stages. IAA decreased and ABA increased with the progression from early to late embryogenesis. Besides providing basic information on the morphophysiological and biochemical changes of zygotic embryogenesis, the results here obtained may provide adequate strategies towards the modulation of somatic embryogenesis in this species as well as in other woody angiosperms.     

Involvement of cation channels and NH4+-sensitive K+ transporters in Na+ uptake by cowpea roots under salinity

Na⁺ accumulation was investigated in the roots of 11-d-old cowpea [Vigna unguiculata (L.) Walp.] plants. The relative contribution of different membrane transporters on Na⁺ uptake was estimated by applying Ca²⁺, K⁺, NH₄ ⁺, and pharmacological inhibitors. Na⁺ accumulation into the root symplast was decreased by half in the presence of 1 mM Ca²⁺ and it was almost abolished by 100 mM K⁺. The inhibitory effect of external NH⁴⁺ on Na⁺ accumulation was more pronounced in the roots of NH₄ ⁺-free growing plants. Na⁺ accumulation was reduced about 73 % by 0.1 mM flufenamate and it was almost blocked by 2 mM quinine. In addition, 20 mM tetraethylammonium and 1.0 mM Cs⁺ decreased Na⁺ accumulation by 28 and 30 %, respectively. These results evidenced that low-affinity Na⁺ uptake by cowpea roots depends on Ca²⁺-sensitive and Ca²⁺-insensitive pathways. The Ca²⁺-sensitive pathway is probably mediated by nonselective cation channels and the Ca²⁺-insensitive one may involve K⁺ channels and to a lesser extent NH₄ ⁺-sensitive K⁺ transporters.     

Rice Resistance to Brown Spot Mediated by Nitrogen and Potassium

This study was undertaken to investigate the effects of both nitrogen (N) and potassium (K) rates on rice resistance to brown spot, caused by the fungus Bipolaris oryzae. Rice plants (cultivar ‘Metica 1’) were grown in soil corrected with 0, 25, 50, 75 and 100 mg of N / kg (as NH₄NO₃) of soil as well as with 25, 50, 75, 125 and 150 mg of K / kg (as KCl) of soil. Thirty‐three‐day‐old plants were inoculated with a suspension of Bipolaris oryzae conidia and the incubation period (IP), number of lesions (NL) per cm² of leaf area and disease severity was evaluated. Disease severity was scored at 24, 48, 72, 96, 120 and 144 h after inoculation and data were used to obtain the area under brown spot progress curve (AUBSPC). Soil plant analysis development (SPAD) index, plant dry weight and concentration of N and K in leaf tissues were also determined for both non‐inoculated (NI) and inoculated (IN) plants. Concentration of N in leaf tissue increased as the N rates in the soil increased. Concentration of K in leaf tissue increased sharply as the K rates in the soil increased for both NI and IN plants. Concentration of K in leaf tissue was not affected by N rates. The IP increased as the N rates increased, but was somewhat less impacted by increasing K rates. The NL decreased as the N rates increased. The NL dramatically declined at the highest K rates. The AUBSPC dramatically declined as the N and K rates in the soil increased. SPAD index values increased as the N and K rates in the soil increased for both NI and IN plants. Plant dry weight increased as the N and K rates in the soil increased for both NI and IN plants. Results from this study suggest that combining high N and K rates may contribute to reducing the intensity of brown spot in rice while improving plant development.