Hydraulic properties of sphagnum peat moss and tuff (scoria) and their potential effects on water availability

The importance of macrostructure to root growth of ryegrass (L. perenne) seedlings sown on the soil surface was studied in two soils in which the macrostructure had resulted mainly from root growth and macro-faunal activity. Sets of paired soil cores were used, one of each pair undisturbed and the other ground and repacked to the field bulk density. Undisturbed and repacked soils were first compared at equal water potentials in the range −1.9 to −300 kPa. At equal water potential, the undisturbed soil always had the greater strength (penetration resistance), and root growth was always greater in the repacked soil with no macrostructure than it was in the soil with macrostructure intact. At equal high strength (low water potentials) it appeared that root growth was better when soils were structured. When strength was low (high water potentials), root growth was better in the unstructured soil. Soils were then compared during drying cycles over 21 days. The average rate at which roots grew to a depth of 60 mm, and also the final percentage of plants with a root reaching 60 mm depth, was greatest in repacked soils without macrostructure. The species of vegetation growing in the soil before the experiment affected root growth in undisturbed soil; growth was slower where annual grasses and white clover had grown compared with soil which had supported a perennial grass. It appears that relatively few roots locate and grow in the macrostructure. Other roots grow in the matrix, if it is soft enough to be deformed by roots. Roots in the matrix of a structured soil grow more slowly than roots in structureless soil of equal bulk density and water potential. The development of macrostructure in an otherwise structureless soil, of the type studied, is of no advantage to most roots. However, once a macrostructure has developed, the few roots locating suitable macropores are able to grow at low water potential when soil strength is high. The importance of macrostructure to establishing seedlings in the field lies in rapid penetration of at least a few roots to a depth that escapes surface drying during seasonal drought. ei]{gnB E}{fnClothier}     

A scanning electron microscope study of normal and vitrified leaves from Datura insignis plantlets cultured in vitro

The surface anatomy of normal and vitreous leaves of plantlets obtained from Datura insignis Barb Rodr nodal segment cultures was compared using scanning electron microscopy. Normal and vitrified leaves are similar in several ways. They are both amphistomatic, and have similar distributions of glandular and non-glandular trichomes. Stomata have similar length, diameter and distribution in normal and vitreous plants. Immature stomata, which have closed pores, and plugged stomata, which contain an amorphous material between their guard cells, occur in both normal and vitrified leaves. Normal and vitreous leaves differ in the frequency of normal and abnormal stomata. Normal stomata have kidney-shaped guard cells and resemble closely those found in field-grown plants, whereas abnormal stomata have deformed guard cells. Normal stomata represent approximately 80% of the total number of stomata in normal leaves, but only 7% of the total number of stomata in vitreous leaves. Abnormal stomata represent 90% of the total number in vitreous leaves. The deformation of guard cells could possibly be a mechanical impediment to stomatal function.     

Low species turnover of upland Amazonian birds in the absence of physical barriers

Aim

One of the oldest and most powerful ways for ecologists to explain distinct biological communities is to invoke underlying environmental differences. But in hyper-diverse systems, which often display high species richness and low species abundance, these sorts of community comparisons are especially challenging. The classic view for Amazonian birds posits that riverine barriers and habitat specialization determine local and regional community composition. We test the tacit, complementary assumption that similar bird communities should therefore permeate uniform habitat between major rivers, regardless of distance.

Location

Upland (terra firme) rainforests of central Amazonia.

Methods

We conducted intensive whole-community surveys of birds in three pairs of 100-ha plots, separated by 40–60 km. We then used dissimilarity indices, cluster analysis, and ordination to characterize differences among the six avian communities.

Results

In all, we detected 244 forest-dependent birds, with an average of 190 species (78%) per plot. Species turnover was negligible, no unique indicator species were found among plot pairs, and all documented species were already known from a complete inventory at one of the three sites.

Main Conclusions

Our study corroborates the classic biogeographical pattern and suggests that turnover contributes little to regional avian diversity within upland forests. Using a grain size of 100 ha, this implies that upland birds perceive the environment as uniform, at least over distances of ~60 km. Therefore, to maximize both local species richness and population persistence, our findings support the conservation of very large tracts of upland rainforest. Our analyses also revealed that the avifauna at Reserva Ducke, encroached by urban sprawl from the city of Manaus, shows the hallmarks of a disturbed community, with fewer vulnerable insectivores. This defaunation signals that even an enormous preserve (10 × 10 km) in lowland Amazonia is not insulated from anthropogenic degradation within the surrounding landscape.     

Characterization of hemocytes from the marine amphipod Parhyale hawaiensis (Dana 1853): Setting the basis for immunotoxicological studies

Hemocytes are circulating blood cells that play a crucial function in amphipods and other crustacean immune systems. The hemocytes of the marine tropical amphipod Parhyale hawaiensis have been used for the evaluation of DNA damage and micronuclei, but they have not been characterized in the scientific literature. The aim of this study was to describe the hemolymph cells of P. hawaiensis and study their phagocytotic activity. Basic dyes were used to differentiate the cell types and the presence of lipids. The total hemocyte counts (THCs) and the proportion and sizes of the hemocyte types were determined. Hemolymph was exposed to Escherichia coli for verification of the presence of phagocytosis. Three cell types, all containing lipids, were identified in P. hawaiensis: granulocytes (oval shape, 13.4 × 7.6 μm), semi-granulocytes (oval shape, 14.1 × 7.2 μm), and hyalinocytes (round shape, 9.6 × 7.2 μm). Those three cell types were found in different percentages in males (64.8%, 31.1%, and 4.2%) and females (70.1%, 28.2%, and 1.7%). THCs for males were 9007 ± 3800 cells per individual and 4695 ± 1892 cells per individual for females. The cells of E. coli were phagocytized by the hemocytes. Our findings increased the knowledge of hemocytes in P. hawaiensis and is a step forward in using hemocyte-based immune responses as an endpoint in ecotoxicology.     

The legacy of forest logging on organic matter inputs and storage in tropical streams

Riparian forests play an important role in stream ecosystems, as they support biodiversity, reduce water erosion, and provide litter that fuels aquatic biota. However, they are affected by great array of anthropogenic threats (e.g., fire, logging, and organic pollution), which alter species composition and their physical structure. Although forest recovery after disturbance such as logging can take decades, the legacy of forest clear-cut logging on key processes in tropical riparian ecosystems is mostly unknown. Here, we investigated how litter inputs (leaves, twigs, and reproductive parts) and storage, key processes for carbon and nutrient recycling and for forest and stream biota, are influenced by riparian vegetation undergoing succession (after 28 years from logging) through the comparison of reference and logged forest sites in the Cerrado biome. Litterfall was overall similar between forest types, but litterfall of twigs was twofold higher at logged than reference sites. Similarly, litter inputs from the bank to the stream (i.e., lateral inputs) and streambed storage were 50–60% higher at logged than reference sites. The higher litterfall observed in logged forests could be related to higher proportion of tree species that are characteristic of primary and secondary successional stages, including fast-growing and liana species, which often are more productive and common in anthropogenic areas. Our results showed that the legacy impact of clear-cut logging, even if residual woody vegetation is maintained in riparian buffers, can shift the type, quantity, and seasonality of litter subsidies to tropical streams. This knowledge should be considered within the context of management and conservation of communities and ecosystem processes in the forest-stream interfaces.     

Assessment of Morpho-Physiological and Biochemical Responses of Perennial Ryegrass to Gamma-Aminobutyric Acid (GABA) Application Under Salinity Stress Using Multivariate Analyses Techniques

Journal of Plant Growth Regulation - Salinity stress is one of the most important global problems that afflicts and limits the growth and development of turfgrass in arid and semi-arid areas....     

Phytochemical Characterization of Cannabis sativa L. Roots from Northeastern Brazil

This article describes the phytochemical study of Cannabis sativa roots from northeastern Brazil. The dried plant material was pulverized and subjected to exhaustive maceration with ethanol at room temperature, obtaining the crude ethanolic extract (Cs-EEBR). The volatile compounds were analyzed by gas chromatography coupled with mass spectrometry (GC/MS), which allowed to identify 22 compounds by comparing the linear retention index (LRI), the similarity index (SI) and the fragmentation pattern of the constituents with the literature. By this technique the major compounds identified were: friedelan-3-one and β-sitosterol. In addition, two fractions were obtained from Cs-EEBR by classical column chromatography and preparative thin layer chromatography. These fractions were analyzed by NMR and IR and together with the mass spectrometry data allowed to identify the compounds: epifriedelanol, friedelan-3-one, β-sitosterol and stigmasterol. The study contributed to the phytochemical knowledge of Cannabis sativa, specifically the roots, as there are few reports on the chemical constituents of this part of the plant.     

Antiproliferative Activity and Ultrastructural Changes in Promastigote and Amastigote forms of Leishmania amazonensis Caused by Limonene-Acylthiosemicarbazide Hybrids

Leishmaniasis is a tropical zoonotic disease. It is found in 98 countries, with an estimated 1.3 million people being affected annually. During the life cycle, the Leishmania parasite alternates between promastigote and amastigote forms. The first line treatment for leishmaniasis are the pentavalent antimonials, such as N-methylglucamine antimoniate (Glucantime®) and sodium stibogluconate (Pentostam®). These drugs are commonly related to be associated with dangerous side effects such as cardiotoxicity, nephrotoxicity, hepatotoxicity, and pancreatitis. Considering these aspects, this work aimed to obtain a new series of limonene-acylthiosemicarbazides hybrids as an alternative for the treatment of leishmaniasis. For this, promastigotes, axenic amastigotes, and intracellular amastigotes of Leishmania amazonensis were used in the antiproliferative assay; J774-A1 macrophages for the cytotoxicity assay; and electron microscopy techniques were performed to analyze the morphology and ultrastructure of parasites. ATZ−S-04 compound showed the best result in both tests. Its IC₅₀, in promastigotes, axenic amastigotes and intracellular amastigotes was 0.35±0.08 μM, 0.49±0.06 μM, and 15.90±2.88 μM, respectively. Cytotoxicity assay determined a CC₅₀ of 16.10±1.76 μM for the same compound. By electron microscopy, it was observed that ATZ−S-04 affected mainly the Golgi complex, in addition to morphological changes in promastigote forms of L. amazonensis.