Acoustic communities in an environmental gradient from native to urban areas in Central Brazil

As urban areas expand due to increasing human populations, natural habitats are diminishing in quantity and quality. We conducted a study to examine the response of diurnal acoustic communities along a gradient of environments, ranging from native to dense urban areas. We hypothesized that acoustic indices would decline with urbanization, transitioning from natural and rural areas to urban environments. We conducted the research in and around Brasília, Central Brazil. We deployed 24 digital recorders in native, rural, low-density and high-density urban areas. We employed five commonly used acoustic indices (ADI, ACI, NDSI, H and BI) to characterize the acoustic communities and represent the existing biodiversity numerically. We initially compared the index values across different land use types using a non-parametric rank sum test. Subsequently, we selected eight landscape metrics and performed a principal component analysis to summarize the surrounding matrix at each sampling point. We then employed generalized linear models to determine if the acoustic indices exhibited the anticipated variations. The results indicated significant variations in all indices among the different land use types, indicating their responsiveness to distinct acoustic communities and environmental characteristics. ADI, H and NDSI exhibited declining values from native to urban areas, while ACI and BI displayed the opposite trend. These findings underscore the influence of landscape structure on acoustic indices. Consequently, we concluded that adopting appropriate landscape planning, mainly through integrating natural and urban areas, could help preserve biodiversity in tropical urban regions.     

Environmental gradients in a southern Europe estuarine system: Ria de Aveiro,Portugal implications for soft bottom macrofauna colonization

Four seasonal sampling surveys were carried out between December 1985 and September 1986 in Canal de Mira (Ria de Aveiro, Portugal). A total of 40 sampling stations, distributed over 13 transects, was used. Salinity, temperature, dissolved oxygen and pH of the water mass were measured. Sediment temperature, and salinity and pH of interstitial water were determined. Sediment variables also included granulometric composition and organic matter contents. Bottom macrofauna samples were collected at each station. Ordination (PCA and MDS) and classification of the sampling stations were performed, using the physicochemical and the biological data sets separately. Average linkage cluster analysis using the unweighted paired-group method, arithmetic averages, was used for both sets of data. With a salinity range from 35.1‰ to 0.0‰, Canal de Mira behaves like a tidally and seasonally poikilohaline estuary. Water temperature (8.5–24.7°C) decreased along the channel towards its inner part during the cold season; an inverse and more pronounced trend was observed during the hot season. Dissolved oxygen contents was generally high during the day (50% to 240% saturation). Oversaturation was observed throughout the growing season, with peaks in areas with large amounts of rooted vegetation. The pH values, largely correlated with dissolved oxygen, ranged from 6.8 to 8.9. Four types of sediment were present in Canal de Mira, medium and muddy sands being dominant. Two major gradients were identified: (i) a typical longitudinal estuarine gradient, associated with distance from the mouth, representing physicochemical variables such as tidal amplitude, salinity and temperature; this gradient was accompanied by an upstream increase in dominance; the community composition changes were mainly related to salinity; (ii) a lateral gradient, related to current velocity, depth and sediment composition; the subtidal community had a comparatively low species richness and abundance. Groups of stations could be recognized along the environmental gradients. Benthic community changes, however, appeared to be gradual rather than marked by abrupt transitions.     

Forest resistance to drought in a humid tropical dipterocarp forest in the Western Ghats of India

Droughts are linked to tree die-offs in the biodiverse humid tropics. We assessed drought response of a Dipterocarp Forest and found a marginal decrease in tree survival, indicating drought resistance. Understory and emergent species were sensitive to drought. Urgent focus is needed to understand drought impacts and plant physiological responses in South Asian forests.     

Natural lignin modulators improve bagasse saccharification of sugarcane and energy cane in field trials

The burgeoning cellulosic ethanol industry necessitates advancements in enzymatic saccharification, effective pretreatments for lignin removal, and the cultivation of crops more amenable to saccharification. Studies have demonstrated that natural inhibitors of lignin biosynthesis can enhance the saccharification of lignocellulose, even in tissues generated several months post-treatment. In this study, we applied daidzin (a competitive inhibitor of coniferaldehyde dehydrogenase), piperonylic acid (a quasi-irreversible inhibitor of cinnamate 4-hydroxylase), and methylenedioxy cinnamic acid (a competitive inhibitor of 4-coenzyme A ligase) to 60-day-old crops of two conventional Brazilian sugarcane cultivars and two energy cane clones, bred specifically for enhanced biomass production. The resultant biomasses were evaluated for lignin content and enzymatic saccharification efficiency without additional lignin-removal pretreatments. The treatments amplified the production of fermentable sugars in both the sugarcane cultivars and energy cane clones. The most successful results softened the most recalcitrant lignocellulose to the level of the least recalcitrant of the biomasses tested. Interestingly, the softest material became even more susceptible to saccharification.     

Isolation and properties of flagella of trypanosomatids.

A procedufe is described for the isolation of flagella of Crithidia fasciculata, Herpetomonas samuelpessoai and Leishmania tarentolae in a highly purified state and giving reasonably good yield. The 3 types of flagella give a similar electrophoretic pattern of proteins. It is shown that H. samuelpessoai and, to a lesser extent, C. fasciculata flagella confer protection against Trypanosoma cruzi infection.     

Turnover of Dopamine and Serotonin and Their Metabolites in the Striatum of Aged Rats

Turnover of dopamine (DA), serotonin [5-hydroxytryptamine (5-HT)], and their metabolites has been measured in adult and aged rats. Turnover rates of 3,4-dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA), and 5-hydroxy-3-indoleacetic acid (5-HIAA) have been assayed from the disappearance rates after blocking by pargyline inhibition of monoamine oxidase (MAO) and from the accumulation rates by probenecid inhibition of the probenecid-sensitive transport system. DA and 5-HT turnover rates have been measured as accumulation rates of 3,4-dihydroxyphenylalanine and 5-hydroxytryptophan, respectively, after central decarboxylase inhibition by 3-hydroxybenzylhydrazine (NSD-1015) and as accumulation rates of DA and 5-HT after pargyline inhibition of MAO. The DA turnover rate after NSD-1015 was 23.9% lower in aged rats than in adults, whereas after pargyline there was no significant difference between the two age groups. The HVA fractional rate constant and turnover after pargyline were lower in aged rats than in adults, and HVA turnover after probenecid was higher in aged rats than in adults. The DOPAC-HVA pathway seems to be reinforced at the expense of DOPAC conjugation. In aged and adult rats whose 5-HT steady-state levels were not statistically different, the 5-HT turnover rate after pargyline and NSD-1015 treatment was lower in aged rats than in adults. An increase of 5-HIAA levels after pargyline and probenecid treatment in aged rats could be due to the handling stress.     

Drought acclimation among tropical forest shrubs (Psychotria,Rubiaceae)

Summary Mechanisms of dry-season drought resistance were evaluated for five evergreen shrubs (Psychotria, Rubiaceae) which occur syntopically in tropical moist forest in central Panama. Rooting depths, leaf conductance, tissue osmotic potentials and elasticity, and the timing of leaf production were evaluated. From wet to dry season, tissue osmotic potentials declined and moduli of elasticity increased in four and five species, respectively. Irrigation only affected osmotic adjustment by P. furcata. The other seasonal changes in leaf tissue properties represented ontogenetic change. Nevertheless, they made an important contribution to dry-season turgor maintenance. Small between-year differences in dry season rainfall had large effects on plant water status. In 1986, 51 mm of rain fell between 1 January and 31 March, and pre-dawn turgor potentials averaged <0.1 MPa for all five Psychotria species in March (Wright 1991). In 1989, 111 mm of rain fell in the same period, pre-dawn turgor potentials averaged from 0.75 to 1.0 MPa for three of the species in April, and only P. chagrensis lost turgor. The relation between leaf production and drought differed among species. P. limonensis was buffered against drought by the lowest dry-season conductances and the deepest roots (averaging 244% deeper than its congeners) and was the only species to produce large numbers of leaves in the dry season. P. chagrensis was most susceptible to drought, and leaf production ceased as turgor loss developed. For the other species, water stress during severe dry seasons may select against dry-season leaf production.     

Ecological aspects of Sargassum muticum (Fucales,Phaeophyta) in Baja California,Mexico: reproductive phenology and epiphytes

The reproductive phenology and epiphytic macroalgae of Sargassum muticum were studied through an annual cycle (September 1987 to November 1988) at two sites on the northwestern coast of Baja California, Mexico, which were subjected to different degrees of wave exposure. Sargassum muticum is a brown alga of Japanese origin, now considered a permanent member of the marine flora of Baja California. A similar reproductive development was observed at both sites, with a maximum percentage of reproductive plants from May to July (spring–summer) and minimum from December to March (winter). Reproductive plants were found throughout the year. A total of 48 species of epiphytes were identified and seasonal variation in their diversity was observed. The greatest diversity was found at the more protected site.     

Effect of Cerebellar Lesions on Monoamine Levels in Various Brain Areas of the Cat

Abstract: Modifications in the content of monoamines after different lesions of the cerebellar cortex were investigated in eight prosencephalic structures of cat's brain. Apart from other minor changes, lesions of the posterior vermis induced significant changes in the thalamus (decrease of DA and increase of 5-HT). Lesions of the cortex of a cerebellar hemisphere, on the other hand, produced an increase of 5-HT in the caudate nucleus and an increase of DA in the hippocampus in addition to a generalized increase of 5-HT in all the prosencephalic structures studied. These findings are discussed in relation to the anatomical connections of the lesioned areas and their expected role in the sleep-wakefulness cycle.     

Cytochemistry and freeze-fracture of membranes isolated from the electrocyte of Electrophorus electricus (L.)

Summary Membranes were isolated from the main electric organ of Electrophorus electricus and studied by means of cytochemistry and freezefracture. The membrane fractions consisted of vesicles inside-in as determined by localization of anionic sites using colloidal iron and cationized ferritin particles. The anionic sites were not homogeneously distributed on the surface of the vesicle. Freeze-fracture showed the presence of intramembranous particles associated with either protoplasmic (P) or extracellular (E) faces of the membrane. Regions of the membrane without particles were observed. The results are discussed in relation to the existence of association between intramembranous particles and membrane receptors.For all correspondence