Congruence and responsiveness in the taxonomic compositions of Amazonian aquatic macroinvertebrate and fish assemblages

Hydrobiologia - Stream degradation in Amazonia is outpacing our ability to effectively monitor it for three key reasons: (1) Many changes are cumulative and occur gradually; (2) Scientists have...     

A novel mode of bathing behavior of hummingbirds recorded in the Brazilian ruby Heliodoxa rubricauda and allies (Aves: Trochilidae)

acta ethologica - The Brazilian ruby, Heliodoxa rubricauda, is a forest species of hummingbird endemic to the Atlantic Forest. It belongs to an Andean clade of birds with robust and strong legs and...     

The antennal benzoic acid receptor cell of the female silk moth <Emphasis Type="Italic">Bombyx mori</Emphasis> L.: structure–activity relationship studies with halogen substitutes

Studies on structure–activity relationships were carried out to characterize the response specificity of the benzoic acid cell of the female of the moth Bombyx mori by means of single sensillum electrophysiological recordings. We demonstrated that this cell type responds best to a natural key substance (benzoic acid) and has similar response profiles for less effective compounds, including various halogen substitutes of benzoic acid, benzaldehyde and other derivates of the key compound. Using different halogen substitutes (F, Cl, Br, I), we showed that the cellular response decreases with increasing atomic size of the substitute and that halogen substitutes were most effective in the meta-position. Thus, m-fluor benzoic acid was even more effective than benzoic acid. These results indicate that a critical feature of the stimulus molecule is the inductive effect generated by the halogen substitutes. Increasing the atomic size of the halogen substitute impairs the recognition of the molecule by the receptor cell, possibly due to steric effects. Decreasing the electron density in the aromatic ring improves the receptor response. The benzoic acid receptor cell can be considered as specialist despite not being involved in pheromone detection as it responds maximally to a key substance and has similar response profiles for less effective compounds.     

Gas chromatography/mass spectrometry characterization of urinary metabolites of danazol after oral administration in human

Danazol (17alpha-pregna-2,4-dien-20-yno [2,3-d]-isoxazol-17beta-ol), is a synthetic derivative of ethisterone, structurally related to stanozolol. For this reason its use as doping agent has been investigated. Danazol (Runch) (200 mg) were orally administered to two healthy male volunteers. Urine samples were collected up to 1-week post-dose. Four new metabolites have been identified in addition to the five previously reported. We propose the monitorization of 6beta-hydroxy-2-hydroxymethyl-1,2-dehydroethisterone and 6beta,16epsilon-dihydroxy-2epsilon-hydroxymethyl-ethisterone by free fraction analysis. In a same way, we proposed to detect the principal isomer of a mono-hydroxylated metabolite of 6beta-hydroxy-2epsilon-hydroxymethylethisterone in the conjugated fraction. We conclude that new metabolites can be included for the detection of danazol abuse since the main metabolite ethisterone is excreted relatively fast in urine.     

Galactomannan hydrolysis and mannose metabolism in Cellvibrio mixtus

Galactomannan hydrolysis results from the concerted action of microbial endo-mannanases, manosidases and alpha-galactosidases and is a mechanism of intrinsic biological importance. Here we report the identification of a gene cluster in the aerobic soil bacterium Cellvibrio mixtus encoding enzymes involved in the degradation of this polymeric substrate. The family 27 alpha-galactosidase, termed CmAga27A, preferentially hydrolyse galactose containing polysaccharides. In addition, we have characterized an enzyme with epimerase activity, which might be responsible for the conversion of mannose into glucose. The role of the identified enzymes in the hydrolysis of galactomannan by aerobic bacteria is discussed.     

Regulation of ventilation in the caiman (Caiman latirostris): effects of inspired CO2 on pulmonary and upper airway chemoreceptors

In order to study the relative roles of receptors in the upper airways, lungs and systemic circulation in modulating the ventilatory response of caiman (Caiman latirostris) to inhaled CO₂, gas mixtures of varying concentrations of CO₂ were administered to animals breathing through an intact respiratory system, via a tracheal cannula by-passing the upper airways (before and after vagotomy), or via a cannula delivering gas to the upper airways alone. While increasing levels of hypercarbia led to a progressive increase in tidal volume in animals with intact respiratory systems (Series I), breathing frequency did not change until the CO₂ level reached 7%, at which time it decreased. Despite this, at the higher levels of hypercarbia, the net effect was a large and progressive increase in total ventilation. There were no associated changes in heart rate or arterial blood pressure. On return to air, there was an immediate change in breathing pattern; breathing frequency increased above air-breathing values, roughly to the same maximum level regardless of the level of CO₂ the animal had been previously breathing, and tidal volume returned rapidly toward resting (baseline) values. Total ventilation slowly returned to air breathing values. Administration of CO₂ via different routes indicated that inhaled CO₂ acted at both upper airway and pulmonary CO₂-sensitive receptors to modify breathing pattern without inhibiting breathing overall. Our data suggest that in caiman, high levels of inspired CO₂ promote slow, deep breathing. This will decrease dead-space ventilation and may reduce stratification in the saccular portions of the lung.