Expression Profiles of Digestive Genes in the Gut and Salivary Glands of Tarnished Plant Bug (Hemiptera: Miridae).

Host plant preference of agricultural pests may shift throughout the growing season, allowing the pests to persist on wild hosts when crops are not available. Lygus Hahn (Hemiptera: Miridae) bugs are severe pests of cotton during flowering and fruiting stages, but can persist on alternative crops, or on weed species. Diversity of digestive enzymes produced by salivary glands and gut tissues play a pivotal role in an organism's ability to utilize various food sources. Polyphagous insects produce an array of enzymes that can process carbohydrates, lipids, and proteins. In this study, the digestive enzyme repertoire of the tarnished plant bug, Lygus lineolaris (Palisot de Beauvois), was identified by high-throughput sequencing followed by cDNA cloning and sequencing. This study identified 87 digestive genes, including 30 polygalacturonases (PG), one ß-galactosidase, three α-glucosidases, six ß-glucosidases, 28 trypsin-like proteases, three serine proteases, one apyrase-like protease, one cysteine protease, 12 lipases, and two transcripts with low similarity to a xylanase A-like genes. RNA-Seq expression profiles of these digestive genes in adult tarnished plant bugs revealed that 57 and 12 genes were differentially expressed in the salivary gland and gut (≥5-fold, P ≤ 0.01), respectively. All polygalacturonase genes, most proteases, and two xylanase-like genes were differentially expressed in salivary glands, while most of the carbohydrate and lipid processing enzymes were differentially expressed in the gut. Seven of the proteases (KF208689, KF208697, KF208698, KF208699, KF208700, KF208701, and KF208702) were not detected in either the gut or salivary glands.

Genome-Wide Analyses Provide Insights into the Scavenging Lifestyle of the Striped Hyena (Hyaena hyaena).

Hyenas (family Hyaenidae) occupy a variety of different niches, of which the striped hyena (Hyaena hyaena) scavenges mainly on the carcasses of animals. We compared its genome with the genomes of nine other mammals, focusing on similarities and differences in chemoreception, detoxification, digestive, and immune systems. The results showed that the striped hyena's immune and digestive system-related gene families have significantly expanded, which was likely to be an adaptive response to its scavenging lifestyle. In addition, 88 and 26 positive selected genes (PSGs) were identified in the immune system and digestive system, respectively, which may be the molecular basis for immune defense system to effectively resist pathogen invasion. Functional enrichment analysis of PSGs revealed that most of them were involved in the immune regulation process. Among them, eight specific missense mutations were found in two PSGs (MHC class II antigen DOA and MHC class II antigen DOB), suggesting important reorganization of the immune system in the striped hyena. Moreover, we identified one cathelicidin gene and four defensin genes in the striped hyenas by genome mining, which have high-efficiency and broad-spectrum antimicrobial activity. Of particular interest, a striped hyena-specific missense mutation was found in the cathelicidin gene. PolyPhen-2 classified the missense mutation as a harmful mutation, which may have aided in immune adaptation to carrion feeding. Our genomic analyses on the striped hyena provided insights into its success in the adaptation to the scavenging lifestyle.

Digestion-related proteins in the tobacco hornworm, Manduca sexta.

Food digestion is vital for the survival and prosperity of insects. Research on insect digestive enzymes yields knowledge of their structure and function, and potential targets of antifeedants to control agricultural pests. While such enzymes from pest species are more relevant for inhibitor screening, a systematic analysis of their counterparts in a model insect has broader impacts. In this context, we identified a set of 122 digestive enzyme genes from the genome of Manduca sexta, a lepidopteran model related to some major agricultural pests. These genes encode hydrolases of proteins (85), lipids (20), carbohydrates (16), and nucleic acids (1). Gut serine proteases (62) and their noncatalytic homologs (11) in the S1A subfamily are encoded by abundant transcripts whose levels correlate well with larval feeding stages. Aminopeptidases (10), carboxypeptidases (10), and other proteases (3) also participate in dietary protein digestion. A large group of 11 lipases as well as 9 esterases are probably responsible for digesting lipids in diets. The repertoire of carbohydrate hydrolases (16) is relatively small, including two amylases, three maltases, two sucrases, two α-glucosidases, and others. Lysozymes, peptidoglycan amidases, and ß-1,3-glucanase may hydrolyze peptidoglycans and glucans to harvest energy and defend the host from microbes on plant leaves. One alkaline nuclease is associated with larval feeding, which is likely responsible for hydrolyzing denatured DNA and RNA undergoing autolysis at a high pH of midgut. Proteomic analysis of the ectoperitrophic fluid from feeding larvae validated at least 131 or 89% of the digestive enzymes and their homologs. In summary, this study provides for the first time a holistic view of the digestion-related proteins in a lepidopteran model insect and clues for comparative research in lepidopteran pests and beyond.

Differential gene expression patterns and colocalization of ATP-gated P2X6/P2X4 ion channels during rat small intestine ontogeny.

Gene coding for ATP-gated receptor ion channels (P2X1-7) has been associated with the developmental process in various tissues; among these ion channel subtypes, P2X6 acts as a physiological regulator of P2X4 receptor functions when the two receptors form heteroreceptors. The P2X4 receptor is involved in pain sensation, the inflammatory process, and body homeostasis by means of Mg(2+) absorption through the intestine. The small intestine is responsible for the absorption and digestion of nutrients; throughout its development, several gene expressions are induced that are related to nutrients received, metabolism, and other intestine functions. Previous work has shown a differential P2X4 and P2X6 protein distribution in the small intestine of newborn and adult rats; however, it is not well-known at what age the change in the relationship between the gene and protein expression occurs and whether or not these receptors are colocalized. In this work, we evaluate P2X4 and P2X6 gene expression patterns by qPCR from embryonic (E18, P0, P7, P17, P30) to adult age in rat gut, as well as P2X6/P2X4 colocalization using qRT-PCR and confocal immunofluorescence in proximal and distal small intestine sections. The results showed that P2X6 and P2X4 gene expression levels of both receptors decreased at the embryonic-perinatal transition, whereas from ages P17 to P30 (suckling-weaning transition) both receptors increased their gene expression levels. Furthermore, P2X4 and P2X6 proteins were expressed in a different way during rat small intestine development, showing a higher colocalization coefficient at age P30 in both intestine regions. Those results suggest that purinergic receptors may play a role in intestinal maturation, which is associated with age and intestinal region.

Midgut Transcriptome of the Cockroach Periplaneta americana and Its Microbiota: Digestion, Detoxification and Oxidative Stress Response.

The cockroach, Periplaneta americana, is an obnoxious and notorious pest of the world, with a strong ability to adapt to a variety of complex environments. However, the molecular mechanism of this adaptability is mostly unknown. In this study, the genes and microbiota composition associated with the adaptation mechanism were studied by analyzing the transcriptome and 16S rDNA pyrosequencing of the P. americana midgut, respectively. Midgut transcriptome analysis identified 82,905 unigenes, among which 64 genes putatively involved in digestion (11 genes), detoxification (37 genes) and oxidative stress response (16 genes) were found. Evaluation of gene expression following treatment with cycloxaprid further revealed that the selected genes (CYP6J1, CYP4C1, CYP6K1, Delta GST, alpha-amylase, beta-glucosidase and aminopeptidase) were upregulated at least 2.0-fold at the transcriptional level, and four genes were upregulated more than 10.0-fold. An interesting finding was that three digestive enzymes positively responded to cycloxaprid application. Tissue expression profiles further showed that most of the selected genes were midgut-biased, with the exception of CYP6K1. The midgut microbiota composition was obtained via 16S rDNA pyrosequencing and was found to be mainly dominated by organisms from the Firmicutes phylum, among which Clostridiales, Lactobacillales and Burkholderiales were the main orders which might assist the host in the food digestion or detoxification of noxious compounds. The preponderant species, Clostridium cellulovorans, was previously reported to degrade lignocellulose efficiently in insects. The abundance of genes involved in digestion, detoxification and response to oxidative stress, and the diversity of microbiota in the midgut might provide P. americana high capacity to adapt to complex environments.

Genetic Ablation of the ClC-2 Cl- Channel Disrupts Mouse Gastric Parietal Cell Acid Secretion.

The present studies were designed to examine the effects of ClC-2 ablation on cellular morphology, parietal cell abundance, H/K ATPase expression, parietal cell ultrastructure and acid secretion using WT and ClC-2-/- mouse stomachs. Cellular histology, morphology and proteins were examined using imaging techniques, electron microscopy and western blot. The effect of histamine on the pH of gastric contents was measured. Acid secretion was also measured using methods and secretagogues previously established to give maximal acid secretion and morphological change. Compared to WT, ClC-2-/- gastric mucosal histological organization appeared disrupted, including dilation of gastric glands, shortening of the gastric gland region and disorganization of all cell layers. Parietal cell numbers and H/K ATPase expression were significantly reduced by 34% (P<0.05) and 53% (P<0.001) respectively and cytoplasmic tubulovesicles appeared markedly reduced on electron microscopic evaluation without evidence of canalicular expansion. In WT parietal cells, ClC-2 was apparent in a similar cellular location as the H/K ATPase by immunofluorescence and appeared associated with tubulovesicles by immunogold electron microscopy. Histamine-stimulated [H+] of the gastric contents was significantly (P<0.025) lower by 9.4 fold (89%) in the ClC-2-/- mouse compared to WT. Histamine/carbachol stimulated gastric acid secretion was significantly reduced (range 84-95%, P<0.005) in ClC-2-/- compared to WT, while pepsinogen secretion was unaffected. Genetic ablation of ClC-2 resulted in reduced gastric gland region, reduced parietal cell number, reduced H/K ATPase, reduced tubulovesicles and reduced stimulated acid secretion.

Chagas disease in the State of Amazonas: history, epidemiological evolution, risks of endemicity and future perspectives

Chagas disease (CD) is a parasitic infection that originated in the Americas and is caused by Trypanosoma cruzi. In the last few years, the disease has spread to countries in North America, Asia and Europe due to the migration of Latin Americans. In the Brazilian Amazon, CD has an endemic transmission, especially in the Rio Negro region, where an occupational hazard was described for piaçaveiros (piassaba gatherers). In the State of Amazonas, the first chagasic infection was reported in 1977, and the first acute CD case was recorded in 1980. After initiatives to integrate acute CD diagnostics with the malaria laboratories network, reports of acute CD cases have increased. Most of these cases are associated with oral transmission by the consumption of contaminated food. Chronic cases have also been diagnosed, mostly in the indeterminate form. These cases were detected by serological surveys in cardiologic outpatient clinics and during blood donor screening. Considering that the control mechanisms adopted in Brazil's classic transmission areas are not fully applicable in the Amazon, it is important to understand the disease behavior in this region, both in the acute and chronic cases. Therefore, the pursuit of control measures for the Amazon region should be a priority given that CD represents a challenge to preserving the way of life of the Amazon's inhabitants.

Biochemical, transcriptomic and proteomic analyses of digestion in the scorpion Tityus serrulatus: insights into function and evolution of digestion in an ancient arthropod.

Scorpions are among the oldest terrestrial arthropods and they have passed through small morphological changes during their evolutionary history on land. They are efficient predators capable of capturing and consuming large preys and due to envenomation these animals can become a human health challenge. Understanding the physiology of scorpions can not only lead to evolutionary insights but also is a crucial step in the development of control strategies. However, the digestive process in scorpions has been scarcely studied. In this work, we describe the combinatory use of next generation sequencing, proteomic analysis and biochemical assays in order to investigate the digestive process in the yellow scorpion Tityus serrulatus, mainly focusing in the initial protein digestion. The transcriptome generated database allowed the quantitative identification by mass spectrometry of different enzymes and proteins involved in digestion. All the results suggested that cysteine cathepsins play an important role in protein digestion. Two digestive cysteine cathepsins were isolated and characterized presenting acidic characteristics (pH optima and stability), zymogen conversion to the mature form after acidic activation and a cross-class inhibition by pepstatin. A more elucidative picture of the molecular mechanism of digestion in a scorpion was proposed based on our results from Tityus serrulatus. The midgut and midgut glands (MMG) are composed by secretory and digestive cells. In fasting animals, the secretory granules are ready for the next predation event, containing enzymes needed for alkaline extra-oral digestion which will compose the digestive fluid, such as trypsins, astacins and chitinase. The digestive vacuoles are filled with an acidic proteolytic cocktail to the intracellular digestion composed by cathepsins L, B, F, D and legumain. Other proteins as lipases, carbohydrases, ctenitoxins and a chitolectin with a perithrophin domain were also detected. Evolutionarily, a large gene duplication of cathepsin L occurred in Arachnida with the sequences from ticks being completely divergent from other arachnids probably due to the particular selective pressures over this group.

Transcriptomic analysis of the lesser spotted catshark (Scyliorhinus canicula) pancreas, liver and brain reveals molecular level conservation of vertebrate pancreas function.

BACKGROUND: Understanding the evolution of the vertebrate pancreas is key to understanding its functions. The chondrichthyes (cartilaginous fish such as sharks and rays) have often been suggested to possess the most ancient example of a distinct pancreas with both hormonal (endocrine) and digestive (exocrine) roles. The lack of genetic, genomic and transcriptomic data for cartilaginous fish has hindered a more thorough understanding of the molecular-level functions of the chondrichthyan pancreas, particularly with respect to their "unusual" energy metabolism (where ketone bodies and amino acids are the main oxidative fuel source) and their paradoxical ability to both maintain stable blood glucose levels and tolerate extensive periods of hypoglycemia. In order to shed light on some of these processes, we carried out the first large-scale comparative transcriptomic survey of multiple cartilaginous fish tissues: the pancreas, brain and liver of the lesser spotted catshark, Scyliorhinus canicula. RESULTS: We generated a mutli-tissue assembly comprising 86,006 contigs, of which 44,794 were assigned to a particular tissue or combination of tissues based on mapping of sequencing reads. We have characterised transcripts encoding genes involved in insulin regulation, glucose sensing, transcriptional regulation, signaling and digestion, as well as many peptide hormone precursors and their receptors for the first time. Comparisons to mammalian pancreas transcriptomes reveals that mechanisms of glucose sensing and insulin regulation used to establish and maintain a stable internal environment are conserved across jawed vertebrates and likely pre-date the vertebrate radiation. Conservation of pancreatic hormones and genes encoding digestive proteins support the single, early evolution of a distinct pancreatic gland with endocrine and exocrine functions in jawed vertebrates. In addition, we demonstrate that chondrichthyes lack pancreatic polypeptide (PP) and that reports of PP in the literature are likely due cross-reaction with PYY and/or NPY in the pancreas. A three hormone islet organ is therefore the ancestral jawed vertebrate condition, later elaborated upon only in the tetrapod lineage. CONCLUSIONS: The cartilaginous fish are a great untapped resource for the reconstruction of patterns and processes of vertebrate evolution and new approaches such as those described in this paper will greatly facilitate their incorporation into the rank of "model organism".

RNA-seq analysis reveals significant transcriptome changes in turbot (Scophthalmus maximus) suffering severe enteromyxosis.

BACKGROUND: Enteromyxosis caused by the intestinal myxozoan parasite Enteromyxum scophthalmi is a serious threat for turbot (Scophthalmus maximus, L.) aquaculture, causing severe catarrhal enteritis leading to a cachectic syndrome, with no therapeutic options available. There are still many aspects of host-parasite interaction and disease pathogenesis that are yet to be elucidated, and to date, no analysis of the transcriptomic changes induced by E. scophthalmi in turbot organs has been conducted. In this study, RNA-seq technology was applied to head kidney, spleen and pyloric caeca of severely infected turbot with the aim of furthering our understanding of the pathogenetic mechanisms and turbot immune response against enteromyxosis. RESULTS: A huge amount of information was generated with more than 23,000 identified genes in the three organs, amongst which 4,762 were differently expressed (DE) between infected and control fish. Associate gene functions were studied based on gene ontology terms and available literature, and the most interesting DE genes were classified into five categories: 1) immune and defence response; 2) apoptosis and cell proliferation; 3) iron metabolism and erythropoiesis; 4) cytoskeleton and extracellular matrix and 5) metabolism and digestive function. The analysis of down-regulated genes of the first category revealed evidences of a connexion failure between innate and adaptive immune response, especially represented by a high number of DE interferon-related genes in the three organs. Furthermore, we found an intense activation of local immune response at intestinal level that appeared exacerbated, whereas in kidney and spleen genes involved in adaptive immune response were mainly down-regulated. The apoptotic machinery was only clearly activated in pyloric caeca, while kidney and spleen showed a marked depression of genes related to erythropoiesis, probably related to disorders in iron homeostasis. The genetic signature of the causes and consequences of cachexia was also demonstrated by the down-regulation of the genes encoding structural proteins and those involved in the digestive metabolism. CONCLUSIONS: This transcriptomic study has enabled us to gain a better understanding of the pathogenesis of enteromyxosis and identify a large number of DE target genes that bring us closer to the development of strategies designed to effectively combat this pathogen.

The novel structure of the cockroach allergen Bla g 1 has implications for allergenicity and exposure assessment.

BACKGROUND: Sensitization to cockroach allergens is a major risk factor for asthma. The cockroach allergen Bla g 1 has multiple repeats of approximately 100 amino acids, but the fold of the protein and its biological function are unknown. OBJECTIVE: We sought to determine the structure of Bla g 1, investigate the implications for allergic disease, and standardize cockroach exposure assays. METHODS: nBla g 1 and recombinant constructs were compared by using ELISA with specific murine IgG and human IgE. The structure of Bla g 1 was determined by x-ray crystallography. Mass spectrometry and nuclear magnetic resonance spectroscopy were used to examine the ligand-binding properties of the allergen. RESULTS: The structure of an rBla g 1 construct with comparable IgE and IgG reactivity to the natural allergen was solved by x-ray crystallography. The Bla g 1 repeat forms a novel fold with 6 helices. Two repeats encapsulate a large and nearly spherical hydrophobic cavity, defining the basic structural unit. Lipids in the cavity varied depending on the allergen origin. Palmitic, oleic, and stearic acids were associated with nBla g 1 from cockroach frass. One unit of Bla g 1 was equivalent to 104 ng of allergen. CONCLUSIONS: Bla g 1 has a novel fold with a capacity to bind various lipids, which suggests a digestive function associated with nonspecific transport of lipid molecules in cockroaches. Defining the basic structural unit of Bla g 1 facilitates the standardization of assays in absolute units for the assessment of environmental allergen exposure.

HlCPL-A, a cathepsin L-like cysteine protease from the ixodid tick Haemaphysalis longicornis, modulated midgut proteolytic enzymes and their inhibitors during blood meal digestion.

Ticks employ a battery of proteases to digest the contents of host blood meals. Host hemoglobin degradation is facilitated by proteolytic networks in the midgut, the first major region of the body where ingested blood comes into contact with the tick's internal tissues. Our previous studies indicated that HlCPL-A, a cathepsin L-like cysteine protease isolated from the midgut of the ixodid tick Haemaphysalis longicornis, is a potent hemoglobinase, and plays important roles in the digestion of blood acquired from a host. In this paper, we report the effects of silencing of the HlCPL-A gene in H. longicornis using RNA interference (RNAi). We observed that the survival of HlCPL-A-silenced ticks was reduced compared with that of controls during blood digestion, most likely due to the compromised ability of ticks to digest blood. The morphological analysis results of midgut lumen were different between HlCPL-A-silenced ticks and controls, indicating that HlCPL-A plays a crucial role in hemolysis in the midgut of ticks. The expression level was analyzed using quantitative RT-PCR-based endogenous expression approach. Compared to that in malE double stranded RNA (dsRNA)-treated ticks, in the midgut of HlCPL-A dsRNA-treated ticks, some proteases and inhibitors related to the hemoglobin digestive cascade were up-regulated while the others were down-regulated. These results suggest that HlCPL-A is related to the multi-enzyme cascade and protease network for hemoglobin digestion. These findings suggest that the hemoglobin digestive cascade may assemble in the midgut of ticks.

Microarray analysis of high-glucose diet-induced changes in mRNA expression in jejunums of C57BL/6J mice reveals impairment in digestion, absorption.

Long term intake of high-glucose diet (HGD) may induce many diseases such as dyslipidemia, fatty liver and diabetes disease. Most of the research for molecular mechanisms of the association between HGD and the above diseases focus on the metabolism of glucose and lipid. However, there are few studies on molecular mechanism of the effect of HGD on digestion and absorption. We used HGD (containing 20% glucose) to feed C57BL/6J mice for 4 weeks, detected the expressions of 13,098 genes in jejunums of C57BL/6J mice with DNA microarray. Microarray analysis showed the expression of genes related to digestive enzyme, gastrointestinal peptide and nutrient transporters were significantly changed, which indicated that HGD induced the suppression of digestive enzyme gene expression, attenuation of alimentary tract movement and nutrient transportation. In one word, the microarray analysis suggested that HGD impaired the function of digestion and absorption in jejunum of C57BL/6J mice. We validated our microarray findings by conducting real-time RT-PCR assays on selected genes and detecting the activities of disaccharidases such as lactase, maltase and sucrase in jejunum of C57BL/6J mice.

RNA interference-mediated knock-down of Bla g 1 in the German cockroach, Blattella germanica L., implicates this allergen-encoding gene in digestion and nutrient absorption.

We used RNA interference (RNAi) to silence the expression of a gene encoding Bla g 1, a human allergen produced by the German cockroach, Blattella germanica L., to study its function in cockroach physiology. Females injected with 1 microg of double-stranded RNA contained 64% less Bla g 1 protein and Bla g 1 mRNA abundance was reduced by 91.4% compared to sham-injected females. Bla g 1 knockdown slowed the pace of weight gain, midgut growth, and colleterial gland and basal oocyte maturation, resulting in delayed egg case formation and lower fecundity. Exogenous juvenile hormone treatments rescued reproduction in RNAi-treated females, suggesting that Bla g 1 silencing lowered endogenous juvenile hormone, probably by reducing food intake and nutrient absorption.

Legumains from the hard tick Haemaphysalis longicornis play modulatory roles in blood feeding and gut cellular remodelling and impact on embryogenesis.

The biology and vectorial capacity of haematophagous ticks are directly related to effective blood feeding and digestion. The midgut-associated proteases in ticks are involved in the blood (Hb) digestion cascade, the molecular mechanisms of which are yet poorly understood. Our previous studies indicated that Haemaphysalis longicornis midgut-specific asparaginyl endopeptidases/legumains, HlLgm and HlLgm2, act in the Hb digestion cascade. Here, we investigated the potential of these enzymes in blood feeding and digestion, midgut remodelling and reproduction of ticks by employing RNA interference (RNAi) techniques. Injection of HlLgm- and HlLgm2 gene-specific double-stranded RNAs into unfed adult female H. longicornis caused gene-specific transcriptional and translational disruptions. RNAi impacted on tick blood feeding leading to death of the feeding ticks, failure of ticks to reach repletion and significant reductions in engorged tick body weight. Histological examination revealed that deletion of legumains resulted in damage to the midgut tissues and disruption of normal cellular remodelling during feeding. Gene knock-down also caused significantly delayed onset of oviposition, reduced number of eggs and, most strikingly, structurally deformed eggs that failed to hatch suggesting imperfect embryogenesis. Synergistic impacts of RNAi were reflected on all parameters evaluated when HlLgm and HlLgm2 were silenced together. These findings suggest that legumains may play modulatory roles in blood feeding and digestion, midgut cellular remodelling and embryogenesis in H. longicornis. Deletion of legumains in H. longicornis would help in controlling the tick population and thereby transmission of diseases to their hosts.

Digestibilidade aparente da dieta e balanço do nitrogênio em suínos de diferentes grupos genéticos com ou sem restrição alimentar / Apparent digestibility of the diet and nitrogen balance in different genetic groups of pigs fed ad libitum or restricted

Um experimento foi realizado com o objetivo de estudar a digestibilidade aparente da dieta e o balanço do nitrogênio em suínos de diferentes grupos genéticos com ou sem restrição alimentar. Foram utilizados 24 suínos machos castrados de três linhagens híbridas comerciais (Agroceres, Dalland e Embrapa), com peso vivo médio inicial de 47,95kg e final de 52,11kg. Os animais foram alojados em gaiolas metabólicas mantidas em ambiente semi-climatizado. Foi utilizado um fatorial 3 x 2 (três linhagens híbridas comerciais com ou sem restrição alimentar), com quatro repetições cada, sendo o animal a unidade experimental. Os grupos genéticos e a restrição alimentar não influenciaram (P>0,05) a digestibilidade aparente da matéria seca, da proteína bruta, do extrato etéreo e a metabolizibilidade da energia. No entanto, a restrição de 20 por cento em relação à alimentação à vontade reduziu (P<0,05) em 20 por cento a excreção urinária, 17 por cento da excreção fecal e 19 por cento da retenção de nitrogênio. Os grupos genéticos comerciais estudados apresentam digestibilidade, metabolização da energia e balanço do nitrogênio semelhantes. A restrição de 20 por cento no consumo de ração não afeta a digestibilidade aparente dos nutrientes e a metabolização da energia.

Changes of in vivo gastrointestinal motor pattern in pacemaker-deficient (WsRC-Ws/Ws) rats.

In vitro studies on pacemaker-deficient W-mutants have revealed a disappearance of rhythmic contraction in their gastrointestinal tracts. Their contractile force has not been diminished, however. In contrast, W-mutants often present dysmoility-like symptoms with distension of the gastrointestinal tract in vivo. Gastrointestinal motility of W-mutant rats was examined in vivo by an extraluminal strain-gauge force transducer method. We examined a normal gastrointestinal motor pattern in the rats with two distinct motor phases, digestive and interdigestive. Moreover, we detected a failure to form an interdigestive contractile complex in pacemaker-deficient rats. The interdigestive motor activity of the gastrointestinal tract is important for cleaning gastrointestinal tract in preparation for the next meal. The impairment of the interdigestive contractile complex may be related to the dysmoility-like symptoms of W-mutant rats in vivo.

Herencia de la mala digestión de lactosa / Heredity in lactose maldigestion

Se revisan los datos publicados sobre la posibilidad de que la mala disgestión de la lactosa del tipo adulto sea de naturaleza hereditaria. Tanto la variabilidad étnica de la frecuencia de esta característica, así como los estudios en gemelos y sobre todo las investigaciones en familias, sugieren que se trata efectivamente de un problema genético. De hecho, los estudios en familias, incluyendo el realizado en México, indican que la mala digestión de lactosa se hereda en forma autosómica recesiva