Red Light Stimulates Feeding Motivation in Fish but Does Not Improve Growth

Nile tilapia fish were individually reared under similar light levels for 8 weeks under five colored light spectra (maximum wavelength absorbance): white (full light spectrum), blue (∼452 nm), green (∼516 nm), yellow (∼520 nm) or red (∼628 nm). The effects of light on feeding, latency to begin feeding, growth and feed conversion were measured during the last 4 weeks of the study (i.e., after acclimation). We found that red light stimulates feeding, as in humans, most likely by affecting central control centers, but the extra feeding is not converted into growth.     

Effect of group size on the aggression strategy of an extirpating stingless bee, Trigona spinipes

Summary. Group aggression influences communication and defense strategies in many social insect communities. Such aggression plays a particularly significant role in the lives of stingless bees, important native Neotropical pollinators, in which the battle for food resources can be deadly and critical to colony survival. However, the effects of group size on individual aggression levels and the spatio-temporal aggression strategy of communal aggressors have not been fully explored. We therefore investigated how group size affects the aggression levels and the spatio-temporal attack strategy (which body parts, and the amount of time spent in attacking each part) in close combats between Trigona spinipes foragers and a natural competitor, Melipona rufiventris. In all trials, T. spinipes foragers competitively excluded M. rufiventris foragers from nearby feeders, exhibiting four levels of aggressive behavior ranging from threat displays to prolonged grappling and decapitation. Surprisingly, aggression levels and spatial strategy corresponded to the size of group attacks. Larger groups of attackers used individually lower aggression levels than small groups of attackers. Smaller groups also attacked appendages linked to escape (legs and wings) with greater frequency than larger groups, which focused on vital central body areas (abdomen, thorax, and head). Increased aggression corresponded to increased risks for attackers and the attacked. All combatants engaging at the highest level of aggression died (100% mortality). Thus the dominance style of T. spinipes may minimize attack risk and maximize victim harm with finely tuned hostility.Received 22 May 2004; revised 18 August 2004; accepted 26 October 2004.     

Subsets of Memory CD4+ T Cell and Bactericidal Antibody Response to Neisseria meningitidis Serogroup C after Immunization of HIV-Infected Children and Adolescents

Meningococcal disease is endemic in Brazil, with periodic outbreaks and case fatality rates reach as high as 18 to 20% of cases. Conjugate vaccines against meningococci are immunogenic in healthy children. However, we have previously shown a poor bactericidal antibody response to a Men C conjugate vaccine in Brazilian HIV-infected children and adolescents after a single vaccine administration. The goal of the present work was to investigate associations between bactericidal antibody response induced by MenC vaccine and the frequency and activation profile (expression of CD38, HLA-DR and CCR5 molecules) of total CD4⁺ memory T cell sub-populations in HIV-1-infected children and adolescents. Responders to vaccination against MenC had a predominance (about 44%) of CD4⁺ T_INTERMEDIATE subset followed by T_TRANSITIONAL memory subset (23 to 26%). Importantly, CD4⁺ T_INT frequency was positively associated with bactericidal antibody response induced by vaccination. The positive correlation persisted despite the observation that the frequency T_INT CD38⁺HLA-DR⁺ was higher in responders. In contrast, CD4⁺ T_{CENTRAL MEMORY} (T_CM) subset negatively correlated with bactericidal antibodies. In conclusion, these data indicate that less differentiated CD⁺ T cells, like T_CM may be constantly differentiating into intermediate and later differentiated CD4⁺ T cell subsets. These include CD4 T_INT subset which showed a positive association with bactericidal antibodies.     

Metabolic effects of antidiabetic drugs on adipocytes and adipokine expression

Several classes of antidiabetic agents have been developed that achieve their hypoglycemic outcomes via various molecular mechanisms. Adipose tissue is a major metabolic and energy-storing tissue and plays an important role in many metabolic pathways, including insulin signaling and insulin sensitivity. Adipose tissue monitors and regulates whole body homeostasis via production and release of potent proteins, such as adipokine and adiponectin, into the circulation. Therefore, any agent that can modulate adipocyte metabolism can, in turn, affect metabolic and glucose homeostatic pathways. Antidiabetic drugs are not only recognized primarily as hypoglycemic agents but may also alter adipose tissue itself, as well as adipocyte-derived adipokine expression and secretion. In the current review, we present the major evidence concerning routinely used antidiabetic agents on adipocyte metabolism and adipokine expression.     

Burrow ornamentation in the fiddler crab (Uca leptodactyla): female mate choice and male–male competition

Non-biological ornamentation is found in the nests and burrows of different kinds of animals. We evaluated here whether sand hoods constructed by male fiddler crabs (Uca leptodactyla) are one of the signals used by males to attract females during courtship. We observed females when they were walking among the males, and we quantified the proportion of females that visited male burrows with and without ornamentation and the choice to stay in a male’s burrow. Females visited more burrows with hoods than burrows without hoods, and they chose significantly more builder males. Male investment in ornamentation nevertheless decreased when the proportion of females increased in the area. Male investment was not correlated with the proportion of non-builder males nearby, but was positively correlated with overall density. The density sex ratio, however, was more male-biased in high-density than in low-density areas suggesting that even if building attracts females, the function could be related to male competition for mates.     

Molecular Modeling and Physicochemical Properties of Supramolecular Complexes of Limonene with α- and β-Cyclodextrins

This study evaluated three different methods for the formation of an inclusion complex between alpha- and beta-cyclodextrin (α- and β-CD) and limonene (LIM) with the goal of improving the physicochemical properties of limonene. The study samples were prepared through physical mixing (PM), paste complexation (PC), and slurry complexation (SC) methods in the molar ratio of 1:1 (cyclodextrin:limonene). The complexes prepared were evaluated with thermogravimetry/derivate thermogravimetry, infrared spectroscopy, X-ray diffraction, complexation efficiency through gas chromatography/mass spectrometry analyses, molecular modeling, and nuclear magnetic resonance. The results showed that the physical mixing procedure did not produce complexation, but the paste and slurry methods produced inclusion complexes, which demonstrated interactions outside of the cavity of the CDs. However, the paste obtained with β-cyclodextrin did not demonstrate complexation in the gas chromatographic technique because, after extraction, most of the limonene was either surface-adsorbed by β-cyclodextrin or volatilized during the procedure. We conclude that paste complexation and slurry complexation are effective and economic methods to improve the physicochemical character of limonene and could have important applications in pharmacological activities in terms of an increase in solubility.     

Feeding Behavior of a Crab According to Cheliped Number

Cheliped loss through autotomy is a common reflexive response in decapod crustaceans. Cheliped loss has direct and indirect effects on feeding behavior which can affect population dynamics and the role of species in the community. In this study, we assessed the impact of autotomy (0, 1, or 2 cheliped loss) on feeding behavior in the crab Pachygrapsus transversus, an omnivorous and abundant species that inhabits subtropical intertidal rocky shores along the South Atlantic Ocean. Autotomy altered crab feeding patterns and foraging behavior; however, the time spent foraging on animal prey or algae was not affected. These results indicate a plasticity of feeding behavior in P. transversus, allowing them to maintain feeding when injured.     

The impact of soybean expansion on mammal and bird,in the Balsas region,north Brasilian Cerrado

In order to analyse the impact of land use change, it is particularly important to know how organisms use resources distributed across a heterogeneous landscape. The main objective of this study is to analyse the potential impact of land use change on bird and mammal fauna, by using a coupled model approach. The CLUE (Conversion of Land Use and its Effects) model has been applied to obtain the spatial pattern of land use change for a scenario with soybean expansion in the Cerrado of Maranhão State in Brazil. These land use change maps were used as the input for the LEDESS (Landscape Ecological Decision and Evaluation Support System) model to evaluate the impact of habitat fragmentation on mammal and bird species. The scenarios demonstrated that high quality habitat for all studied species will be lost in the future when current trends in agricultural expansion continue, but these changes will have species-specific impacts. The most relevant ecological impact under the explored scenarios was habitat fragmentation expressed by the increase the number of habitat clusters. The coupled model approach of LEDESS and CLUE made it possible to project the spatial impact of soybean expansion on habitat dynamics in the studied region. This model approach can help to design effective ecological infrastructure to facilitate species survival and to implement an effective habitat network in the Balsas region.     

Influence of plant growth regulators and water stress on ramet induction,rosette engrossment,and fructan accumulation in <Emphasis Type="Italic">Agave tequilana</Emphasis> Weber var. Azul

Agave tequilana Weber var. Azul plants reproduce asexually by producing ramets. Continuous production of ramets throughout the vegetative cycle of the parent delays the time of harvesting of heads for tequila production. Little is known about the factors influencing their emergence. Heads are engrossed rosettes where fructans are stored. We show here that, in plantlets grown in vitro, growth regulators such as 2,4-dichlorophenoxyacetic acid (2,4-D), a combination of 1-naphthaleneacetic acid (NAA)/6-benzyladenine (BA), or abscisic acid (ABA) increased the production of ramets, whereas BA, NAA, gibberellic acid (GA₃), glycerol, or a combination of glycerol/ABA decreased ramet production. Plantlets that developed ramets did not form heads. Head formation was improved on solid media in the presence of BA, NAA, the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC), or the water stress inducer polyethylene glycol (PEG). Basal Murashige–Skoog (MS) liquid media also enhanced rosette engrossment, which was further increased by addition of ACC or PEG. In contrast, CoCl₂, an ethylene biosynthesis inhibitor, reduced rosette engrossment. Furthermore, heads from A. tequilana plantlets grown in tissue culture in MS media, or in MS media supplemented with NAA, ACC or PEG, showed fructan concentrations 10–30 times higher than in leaves from greenhouse-grown plants. Our results indicated that BA, NAA, water stress, and ethylene are critical regulators of rosette engrossment, whereas asexual reproduction in A. tequilana seems to be controlled by a complex hormonal network.     

Poverty,dirt, infections and non-atopic wheezing in children from a Brazilian urban center

Background

The causation of asthma is poorly understood. Risk factors for atopic and non-atopic asthma may be different. This study aimed to analyze the associations between markers of poverty, dirt and infections and wheezing in atopic and non-atopic children.

Methods

1445 children were recruited from a population-based cohort in Salvador, Brazil. Wheezing was assessed using the ISAAC questionnaire and atopy defined as allergen-specific IgE ≥0.70 kU/L. Relevant social factors, environmental exposures and serological markers for childhood infections were investigated as risk factors using multivariate multinomial logistic regression.

Results

Common risk factors for wheezing in atopic and non-atopic children, respectively, were parental asthma and respiratory infection in early childhood. No other factor was associated with wheezing in atopic children. Factors associated with wheezing in non-atopics were low maternal educational level (OR 1.49, 95% CI 0.98-2.38), low frequency of room cleaning (OR 2.49, 95% CI 1.27-4.90), presence of rodents in the house (OR 1.48, 95% CI 1.06-2.09), and day care attendance (OR 1.52, 95% CI 1.01-2.29).

Conclusions

Non-atopic wheezing was associated with risk factors indicative of poverty, dirt and infections. Further research is required to more precisely define the mediating exposures and the mechanisms by which they may cause non-atopic wheeze.