Arterial acid-base status during digestion and following vascular infusion of NaHCO3 and HCl in the South American rattlesnake, Crotalus durissus

Digestion is associated with gastric secretion that leads to an alkalinisation of the blood, termed the alkaline tide. Numerous studies on different reptiles and amphibians show that while plasma bicarbonate concentration ([HCO3-](pl)) increases substantially during digestion, arterial pH (pHa) remains virtually unchanged, due to a concurrent rise in arterial PCO2 (PaCO2) caused by a relative hypoventilation. This has led to the suggestion that postprandial amphibians and reptiles regulate pHa rather than PaCO2.Here we characterize blood gases in the South American rattlesnake (Crotalus durissus) during digestion and following systemic infusions of NaHCO3 and HCl in fasting animals to induce a metabolic alkalosis or acidosis in fasting animals. The magnitude of these acid-base disturbances were similar in magnitude to that mediated by digestion and exercise. Plasma [HCOT] increased from 18.4+/-1.5 to 23.7+/-1.0 mmol L-1 during digestion and was accompanied by a respiratory compensation where PaCO2 increased from 13.0+/-0.7 to 19.1+/-1.4 mm Hg at 24 h. As a result, pHa decreased slightly, but were significantly below fasting levels 36 h into digestion. Infusion of NaHCO3 (7 mmol kg(-1)) resulted in a 10 mmol L-1 increase in plasma [HCO3-] within 1 h and was accompanied by a rapid elevation of pHa (from 7.58+/-0.01 to 7.78+/-0.02). PaCO2, however, did not change following HCO3- infusion, which indicates a lack of respiratory compensation. Following infusion of HCl (4 mmol kg(-1)), plasma pHa decreased by 0.07 units and [HCO3-](pl) was reduced by 4.6 mmol L-1 within the first 3 h. PaCO2, however, was not affected and there was no evidence for respiratory compensation.Our data show that digesting rattlesnakes exhibit respiratory compensations to the alkaline tide, whereas artificially induced metabolic acid-base disturbances of same magnitude remain uncompensated. It seems difficult to envision that the central and peripheral chemoreceptors would experience different stimuli during these conditions. One explanation for the different ventilatory responses could be that digestion induces a more relaxed state with low responsiveness to ventilatory stimuli. (C) 2005 Elsevier B.V. All rights reserved.

In situ hybridization of bat chromosomes with human (TTAGGG)n probe, after previous digestion with Alu I

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Ruminal parameters analyzed in remaining digestion residue of roughages in the in vitro/gas system

O desempenho animal é a medida mais direta de se avaliar a qualidade dos alimentos. Entretanto, dados de desempenho são insuficientes para se detectar as possíveis interações que possam ocorrer no ambiente ruminal. O objetivo do presente trabalho foi avaliar os possíveis efeitos associativos nas concentrações de ácidos graxos voláteis (AGVs), nitrogênio amoniacal (N-NH3) e pH da fração líquida remanescente da digestão da matéria seca (MS) de volumosos exclusivos (cana-de-açúcar= CN; capim-elefante com 60 dias= CP60 e 180 dias= CP180 de crescimento; e silagem de milho= SIL) e suas combinações (cana-de-açúcar+silagem de milho= CNSIL; cana-de-açúcar+capim-elefante-60d= CNCP60; cana-de-açúcar+capim-elefante-180d= CNCP180; silagem de milho+capim-elefante-60d= SILCP60; silagem de milho+capim-elefante-180d= SILCP180) na proporção de 50% na MS, que levam a resultados de desempenhos positivos ou negativos de bovinos. As concentrações de AGVs, N-NH3 e pH dos tratamentos foram: CN= 56,9 mmol L-1, 50,1 mg dL-1, 5,7; CNSIL= 61,4 mmol L-1, 50,7 mg dL-1, 5,8; CNCP60= 54,7 mmol L-1, 47,6 mg dL-1, 5,8; CNCP180= 45,4 mmol L-1, 49,4 mg dL-1, 6,0; SIL= 57,2 mmol L-1, 54,0 mg dL-1, 5,8; SILCP60= 57,1 mmol L-1, 53,1 mg dL-1, 5,9; SILCP180= 55,9 mmol L-1, 52,3 mg dL-1, 6,0; CP60= 58,1 mmol L-1, 49,4 mg dL-1, 5,9; CP180= 44,0 mmol L-1, 46,4 mg dL-1, 6,1. Os carboidratos não estruturais e amido, aliados à fibra e proteína, contribuíram para que ocorresse o efeito associativo positivo na mistura 50:50 cana/silagem. Isso pode ter propiciado os melhores resultados de desempenho em bovinos devido ao elevado padrão fermentativo.

Ultrastructural evidences of the occurrence of digestion and absorption of organic solutes in bees ileum (Melipona quadrifasciata anthidioides - Hymenoptera, Apidae)

The ultrastructural aspects of the ileum of Melipona quadrifasciata anthidioides, a stingless bee whose workers obtain their protein requirements from pollen, present morphological evidences of digestion and absorption. These evidences are represented by special relationships between food particles and the bacterial nora present and between their assemblage and the ileum wall, mainly in the ileum three anterior fourths. The apical features of the epithelium also are indicative of organic material absorption.

Analytical procedure for total mercury determination in fishes and shrimps by chronopotentiometric stripping analysis at gold film electrodes after microwave digestion

A method for the total mercury determination in fish and shrimps employing chronopotentiometric stripping analysis on gold film electrodes is described. Fish and shrimp tissues were digested using a microwave oven equipped with closed vessels. We developed a microwave heating program which decomposed all the samples employing diluted nitric acid and hydrogen peroxide. The proposed method was validated by analyzing a certified reference material and then applied for different fish species from fresh water and seawater acquired in local markets of São Paulo city, Brazil. The Brazilian legislation establishes 0.5 and 1 mg per kilogram of fish as upper limit of mercury for omnivorous and predator species, respectively. Except for blue shark tissues, the mercury content was situated below 0.5 mu g g(-1) for all the analyzed samples. The detection limit of the proposed method was calculated as 5 ng g(-1) of sample utilizing 5 minutes of electrodeposition (+300 mV vs. Ag/AgCl) on the gold electrode. (c) 2006 Elsevier Ltd. All rights reserved.

Effect of anaerobic digestion and initial pH on metal bioleaching from sewage sludge

The effects of anaerobic digestion and initial pH on the bioleaching of metals from sewage sludge were investigated in shake flask experiments. A strain of Acidithiobacillus thiooxidans was employed in the assays using secondary and anaerobic sludges, which resulted in similar solubilization yields of the metals chromium, copper, lead, nickel, and zinc for both the sludges investigated. The effect of initial pH (7.0 and 4.0) on metal bioleaching was assayed by using the anaerobic sludge inoculated with indigenous sulfur-oxidizing thiobacilli. Although the time required to reach the end of the experiment (final pH close to 1.0) was shortened at initial pH of 4.0, final metal solubilization was not significantly different for both initial pH values, resulting in higher solubilization yields for copper, nickel, and zinc (higher than 80%). Chromium and lead presented solubilization yields close to 50%. The results obtained in this work showed that the metal bioleaching process can be applied to sewage sludge regardless of the type of sludge and without the requirement of pH adjustment.

Chitinolytic activities in the gut of Aedes aegypti (Diptera : Culicidae) larvae and their role in digestion of chitin-rich structures

Mosquito larvae are believed to be capable of digesting chitin, an insoluble polysaccharide of N-acetylglucosamine, for their nutritional benefit. Studies based on physiological and biochemical assays were conducted in order to detect the presence of chitinase activities in the gut of the detritus-feeding Aedes aegypti larvae. Larvae placed for 24 h in suspensions of chitin azure were able to digest the ingested chitin. Semi-denaturing PAGE using glycol chitin and two fluorogenic substrate analogues showed the presence of two distinct chitinase activities: an endochitinase that catalyzed the hydrolysis of chitin and an endochitinase that cleaved the short substrates [4MU(GlcNAc)(3)] and [4MU(GlcNAc)(2)] that hydrolyzed the chitobioside [4MU(GlcNAc)(2)]. The endochitinase had an extremely broad pH-activity against glycol chitin and chitin azure, pH ranging from 4.0 to 10.0. When the substrate [4MU(GlcNAc)(3)] was used, two activities were observed at pH ranges 4.0-6.0 and 8.0-10.0. Chitinase activity against [4MU(GlcNAc)(3)] was detected throughout the gut with the highest specific activity in the hindgut. The pH of the gut contents was determined by observing color changes in gut after feeding the larvae with color indicator dyes. It was observed a correlation between the pH observed in the gut of feeding larvae (pH 10-6.0) and the optimum pH for gut chitinase activities. In this work, we report that gut chitinases may be involved in the digestion of chitin-containing structures and also in the partial degradation of the chitinous peritrophic matrix in the hindgut. (C) 2003 Elsevier B.V. All rights reserved.

GENETIC INTERRELATIONSHIPS OF PROTEOLYTIC CLOSTRIDIUM-BOTULINUM TYPE-A, TYPE-B, AND TYPE-F AND OTHER MEMBERS OF THE CLOSTRIDIUM-BOTULINUM COMPLEX AS REVEALED BY SMALL-SUBUNIT RIBOSOMAL-RNA GENE-SEQUENCES

The phylogenetic interrelationships of members of the Clostridium botulinum complex of species was investigated by direct sequencing of their 16S rRNA genes. Comparative analysis of the 16S rRNA sequences demonstrated the presence of four phylogenetically distinct lineages corresponding to: i) proteolytic C. botulinum types Al B, and F, and C. sporogenes, ii) saccharolytic types B, E and F, iii) types C and D and C. novyi type A, and iv) type G and C. subterminale. The phylogenetic groupings obtained from the 16S rRNA were in complete agreement with the four divisions recognised within the 'species complex' on the basis of phenotypic criteria.

The thermogenesis of digestion in rattlesnakes

Some snakes have a feeding regime characterized by the infrequent ingestion of relatively large meals, causing impressive increments in post-prandial metabolism. Metabolism remains elevated for many days, while digestion proceeds, resulting in considerable investment of time and energy. Snakes actively adjust thermoregulatory behavior to raise their body temperature during digestion, exhibiting a post-prandial thermophilic response that accelerates digestion at the expense of higher metabolic rates. In the present study, we investigated the possibility that endogenously derived heat, originating as a byproduct of the post-prandial increase in metabolism, could itself contribute to the elevated body temperature during digestion in the South American rattlesnake Crotalus durissus. We assessed heat production, at a constant environmental temperature, by taking infrared (IR) images of snakes during fasting and after being fed meals varying from 10% to 50% of their own body masses. Our results show clearly that digesting rattlesnakes have significantly increased body temperatures, even when precluded from adjusting their thermoregulatory behavior. The feeding-derived thermogenesis caused the surface body temperature of rattlesnakes to increase by 0.9-1.2degreesC, a temperature change that will significantly affect digestive performance. The alterations in body temperature following feeding correlated closely with the temporal profile of changes in post-prandial metabolism. Moreover, the magnitude of the thermogenesis was greater for snakes fed large meals, as was the corresponding metabolic response. Since IR imaging only assesses surface temperatures,, the magnitude of the thermogenesis and the changes in deep core temperature could be even more pronounced than is reported here.

Neo-clerodane diterpenoid, a new metalloprotease snake venom inhibitor from Baccharis trimera (Asteraceae): anti-proteolytic and anti-hemorrhagic properties

Many plants are used in traditional medicine as active agents against various effects induced by snakebite. Few attempts have been made however to identify the nature of plain natural products with anti-ophidian properties. Baccharis trimera (Less) DC (Asteraceae), known in Brazil as carqueja. has been popularly used to treat liver diseases. rheumatism. diabetes, as well as digestive, hepatic and renal disorders. The active component was identified as 7alpha-hydroxy-3,13-clerodadiene-16,15:18,19-diolide, C20H28O5, (clerodane diterpenoid, Bt-CD). We report now the anti-proteolytic and anti-hemorrhagic propenies against snake venoms of a Bt-CD inhibitor from B. trimera. Bt-CD exhibited full inhibition of hemorrhage and proteolytic activity caused by Bothrops snake venoms. The inhibitor was able to neutralize the hemorrhagic, fibrinogenolytic and caseinolytic activities of class P-I and III metalloproteases isolated from B. neuwiedi and B. jararacussu venoms. No inhibition of the coagulant activity was observed. Bt-CD also partially inhibited the edema induced by other crude venoms, metallopronteases, basic and acidic phospholipases A(2). To further elucidate the inhibitory specificity of Bt-CD against metalloproteases isolated from snake venoms, a deeper understanding of its Structure and function is necessary. Furthermore, the potential use of these inhibitors to complement anti-venom as an alternative treatment of snakebite envenomations needs to be evaluated in future Studies. (C) 2004 Elsevier B.V.. All rights reserved.

Effect of age on seed digestion in parrots (Amazona aestiva)

The objective of this study was to compare the capacity of adult (more than 3 yr old) and young (less than 1 yr old) true parrots to digest seeds that are normally included in their diet in captivity, particularly soybean, sunflower, and corn. All the seeds were offered for 5 d with an interval of 15 d between different diets. The seeds of soybean and corn were boiled for 15 min and soaked in water at ambient temperature for 12 h before being fed to the birds. There were no differences in the digestibilities of crude protein and fats (ether extract) among animals, but the digestibilities of dry matter and crude fiber by the adult animals were higher than those of the young ones. The digestibility of carbohydrate (nitrogen-free extract) by adult birds was higher only for sunflower seeds. It is concluded that the capacity of parrots to digest fiber may change according to the age of the animal. Since the digestion of fiber depends on the action of microorganisms, these results suggest that the colonization of the gastrointestinal tract is delayed or very slow in young parrots.

Sequencing wasp venom peptides by endopeptidase digestion and nested collision-induced dissociation/post-source decay methods

A method incorporating nested collision-induced dissociation/post-source decay (CID/PSD) combined with endopeptidase digestion is described as an approach to determine the sequence of N-terminally modified peptides. The information from immonium and related ions observed in the CID/PSD spectrum was used for the selection of a suitable endopeptidase for the digestion of peptides. Rapid and reliable assignment of peptide sequence was performed by the comparison of CID/PSD spectra of both intact and endopeptidese-digested peptide fragments, since the assignments of the observed fragment ions to either N- or C-terminal ions can thus be carried out unambiguously. This nested CID/PSD method was applied to the sequence determination of two peptides from the solitary wasps Anoplius samariensis and Batozonellus maculifrons (pompilid wasps), which could not be sequenced by the Edman method due to N-terminal modification. Copyright (C) 2002 John Wiley Sons, Ltd.

Role of different proteolytic pathways in degradation of muscle protein from streptozotocin-diabetic rats

In vitro rates of overall proteolysis and the activities of four different proteolytic pathways (lysosomal, Ca2+ dependent, ATP dependent, and ATP independent), as well as rates of protein synthesis, were measured in soleus and extensor digitorum longus (EDL) muscles from streptozotocin- diabetic rats. In the acute phase (1-3 days) of diabetes, there was an increase in overall proteolysis that coincided with an increased activity of the Ca2+-dependent pathway in both soleus and EDL and of the ATP-dependent pathway in EDL. After longer periods (5-10 days) of diabetes, the overall rate of protein degradation decreased and reached values similar to or even lower than those of controls as a result of a reduction in the activities of Ca2+-dependent and ATP-dependent pathways. No change was detected at any time interval in the activity of the intralysosomal proteolytic system in muscles from diabetic animals. Rates of protein synthesis were already reduced 24 h after diabetes induction and decreased further thereafter. Insulin treatment restored to normal the activities of the proteolytic pathways and rates of protein synthesis.

Relationship of venom ontogeny and diet in Bothrops

We studied ontogenetic changes in venom toxicity of the pitvipers Bothrops jararaca and B. alternatus in order to evaluate the relationship between venom action and diet. Toxicity tests (LD50) were performed for the venoms of adult and juvenile snakes on mice and bullfrog froglets, which represented endothermic and ectothermic prey respectively. The venom of juveniles of B. jararaca, but not of B. alternatus, had a higher toxicity on anurans than that of adults. This finding is consistent with the feeding habits of these two species, because juveniles of B. jararaca feed mainly on small anurans and lizards, shifting to endothermic prey at maturity, whereas B. alternatus preys mainly on endotherms throughout its life. Venom toxicity in endotherms was higher for adults of B. jararaca compared to juveniles, a feature not observed for B. alternatus. It is proposed that prey death/immobilization is the main function of the venom of juvenile snakes. As the snake grows, the digestive role of venom may become increasingly important, because adults prey upon large and bulky prey. The importance of adult venoms in prey digestion is reflected in their higher proteolytic activity.