Digestive Tract Tissues Research Articles

BTNL2, a Butyrophilin/B7-Like Molecule, Is a Negative Costimulatory Molecule Modulated in Intestinal Inflammation

Butyrophilin-like 2 (BTNL2) is a butyrophilin family member with homology to the B7 costimulatory molecules, polymorphisms of which have been recently associated through genetic analyses to sporadic inclusion body myositis and sarcoidosis. We have characterized the full structure, expression, and function of BTNL2. Structural analysis of BTNL2 shows a molecule with an extracellular region containing two sets of two Ig domains, a transmembrane region, and a previously unreported cytoplasmic tail. Unlike most other butyrophilin members, BTNL2 lacks the prototypical B30.2 ring domain. TaqMan and Northern blot analysis indicate BTNL2 is predominantly expressed in digestive tract tissues, in particular small intestine and Peyer's patches. Immunohistochemistry with BTNL2-specific Abs further localizes BTNL2 to epithelial and dendritic cells within these tissues. Despite its homology to the B7 family, BTNL2 does not bind any of the known B7 family receptors such as CD28, CTLA-4, PD-1, ICOS, or B and T lymphocyte attenuator. Because of its localization in the gut and potential role in the immune system, BTNL2 expression was analyzed in a mouse model of inflammatory bowel disease. BTNL2 is overexpressed during both the asymptomatic and symptomatic phase of the Mdr1a knockout model of spontaneous colitis. In functional assays, soluble BTNL2-Fc protein inhibits the proliferation of murine CD4(+) T cells from the spleen, mesenteric lymph node, and Peyer's patch. In addition, BTNL2-Fc reduces proliferation and cytokine production from T cells activated by anti-CD3 and B7-related protein 1. These data suggest a role for BTNL2 as a negative costimulatory molecule with implications for inflammatory disease.

The contribution of pathologic diagnosis and research of the faculty members engaged in teaching histology and embryology to undergraduate medical studies

The theoretical and practical aspects of teaching are generally defined by the curriculum, but professional experience plays an important role as well. The teaching experience of the faculty members is developed through health services, education and research. THE DEPARTMENT OFHISTOLOGY AND EMBRIOLOGY: This paper reviews the activities of the teaching staff of the Department of Histology and Embryology, pointing to the importance of pathologic diagnostics and research. It underlines the necessity of using some non-standard histologic staining methods on some tissues, organs and pathogens, as well as the results of experimental studies of the endocrine system. The experimental tumor models are used to demonstrate the interdependence of the endocrine and immune systems. Modalities and possibilities of regeneration of the digestive tract and connective tissue mucosa are explained This paper also deals with histologic criteria used for assessment of fetal age and in the diagnosis of developmental malformations. Linear and stereologic methods, used in quantification of normal morphology, the degree of pathologic changes, and regeneration of normal structures in the courses of and after therapy, are given. The authors particularly emphasized the importance of above-mentioned activities in the teaching of Histology and Embryology to undergraduate students.

Down-regulation of FHIT inhibits apoptosis of colorectal cancer: Mechanism and clinical implication

Fragile histidine triad (FHIT) gene, a candidate tumor suppressor gene located at 3p14.2, has been shown to be involved in carcinogenesis of many human tissues, including digestive tract tissues. However, the expression and role of FHIT in the initiation and the development of the colorectal cancer (CRC) are poorly understood. In our present study, we have demonstrated that the FHIT gene exhibits significantly decreased expression in human CRC compared to colorectal adenoma and normal colorectal tissue by tissue microarray (TMA). The positive of FHIT gene expression in normal colorectal tissue, adenoma and adenocarcinoma were 93.75%, 68.75% and 46.25%, respectively. We showed that decreased FHIT expression was significantly correlated with the progression of colorectal carcinoma (P<0.05) as well as differentiation and lymph node metastasis (P<0.05). Two somatic mutations in the FHIT gene were also detected in human CRC. The presence of these mutations correlated significantly with decreased FHIT expression in the human CRC. In addition, we identified decreased FHIT expression resulting in apoptosis inhibition and decreasing apoptosis associated with abnormal levels of some pro- and anti-apoptotic proteins (Bax, Bcl-2 and Survivin) by TUNEL and TMA. Our results demonstrated that the mutation in the FHIT gene significantly reduced FHIT expression in human CRC. Both TUNEL and TMA experiments demonstrated significantly inhibited apoptosis by down-regulation of Bax and up-regulation of Survivin and Bcl-2. Collectively, these studies identify the mechanism by which an important tumor suppressor gene, FHIT, inactivated specifically in human CRC, and contributes to our understanding of the mechanism of colorectal carcinogenesis.

Absorption and Digestive Tract Metabolism of 2-Hydroxy-4-Methylthiobutanoic Acid in Lambs

Anabolic availability of the hydroxyl methionine analog, 2-hydroxy-4-methylthiobutanoic acid (HMTBA), given as oral doses to lambs, was quantified both directly as appearance in the portal vein and as synthesis to Met by digestive tract tissues. Eight lambs, prepared with vascular catheters in the mesenteric and portal veins plus the aorta, received twice daily for 7 d either 0.46g or 2g of HMTBA. On d 7, [1-13C]HMTBA was supplied as 1 oral dose while [methyl-2H3]Met was infused into the jugular vein. Peak absorption as HMTBA occurred 70 to 90min after the oral dose. All digestive tract tissues converted HMTBA to Met, equivalent to 24% of the Met provided by the diet for the larger HMTBA dose. Overall, total availability of HMBTA averaged 17.9% of the dose (range 10.6 to 27.9%), with 12.5% (range 7 to 22%) as absorbed HMBTA and the remainder as Met synthesized by digestive tract tissues. Release of 13CO2 into the portal vein accounted for another 23% of the dose. In all digestive tract tissues, the d-isomer was present in a smaller proportion than in the dose. In terms of whole-body kinetics, HMTBA loss from the plasma followed first-order kinetics, with a mean biological half-life of 76min. Using this value, a simple model was devised to estimate HMTBA absorption based on peripheral plasma samples. When compared with direct measures of absorption, the model gave a slope of 0.81 (R2=0.68) and offers a practical means to test HMTBA availability to animals.

Bovine lactoferrin: benefits and mechanism of action against infectionsThis paper is one of a selection of papers published in this Special Issue, entitled 7th International Conference on Lactoferrin: Structure, Functions, and Applications, and has undergone the Journal's usual peer review process.

Ingestion of bovine lactoferrin (bLF) has been reported to show anti-infective, anti-cancer, and anti-inflammatory effects. In particular, it has become evident that oral bLF had a beneficial effect on infections of both digestive and nondigestive tract tissue in various animal models. Furthermore, the effects of bLF have been indicated in clinical studies on patients with Helicobacter pylori infection, chronic hepatitis C, tinea pedis, and other diseases. Immunomodulation in the intestine and systemic sites has been suggested to mediate the protective effects of oral bLF against infection. Recently, we demonstrated the beneficial effects of oral bLF in influenza virus infected mice. BLF administration reduced the lung consolidation score and the number of infiltrating leukocytes in bronchoalveolar lavage fluid. We also investigated the effect of oral bLF on the transcription of genes related to immunity in the small intestine of mice using the quantitative RT-PCR method. We found that intake of bLF increased the expression of IL-12p40, IFN-beta, and NOD2. Thus, oral bLF activates the transcription of important immune-related genes in the small intestine, and such transcriptional activation may promote systemic host immunity.

Malabsorption syndrome in broilers

Malabsorption syndrome (MAS) is a multifactorial disease that causes intestinal disorders in broilers due to infection of the gastrointestinal tract with different infectious agents. The exact aetiology is unknown, although several viruses are isolated from MAS affected chickens. None of these isolated infectious agents alone inducted the malabsorption syndrome. MAS in broilers is characterised by poor growth and lesions in the GI-tract, mainly in the small intestine. Experimentally, MAS can be induced in one-day old broilers by oral inoculation of homogenates obtained from digestive tract tissues of MAS affected broilers. Susceptibility to the MAS syndrome differs between broiler lines. The susceptibility to MAS is correlated with the severity of the lesions, apoptosis and heterophil infiltration of the jejunum. Susceptibility to MAS is also related to the frequency of CD4 and CD8 positive T-cells in the intestinal villus and the mRNA expression level of different cytokines in control and in MAS induced broilers. With the use of micro-arrays differences in gene expression levels between broiler lines that differ in MAS susceptibility were observed. From these experiments genes that are immune and food absorption related were identified. If some of these genes or the T-cell population in the gut and the other MAS susceptible related parameters could predict or prevent MAS susceptibility in broilers needs to be further investigated but can be interestingly for breeding programmes.

Contribution of Infection to Increased Mortality in Women After Cardiac Surgery

Women have higher mortality rates after coronary artery bypass graft (CABG) surgery compared with men. Explanations for this sex difference are controversial. The objective of this study was to assess whether infection contributes to the increased risk of mortality in women. We conducted a cohort study of 9218 Michigan Medicare beneficiaries hospitalized for CABG surgery. The prevalence of infection at any site during hospitalization was determined. Patients were followed up for 100 days after surgery to assess vital status. Analyses were conducted using proportional hazards regression and population attributable risk. Women hospitalized for CABG surgery were more likely to have an infection than men (16.1% vs 9.8%, P<.001), regardless of age, race, type of admission, hospital volume, or presence of comorbidities. Infections of the respiratory tract, urinary tract, digestive tract, and skin and subcutaneous tissue were more common in women than in men. The risk of death in men increased 3-fold with infection, whereas the risk in women increased 1.8-fold. The interaction between infection and sex on mortality was significant after adjusting for age, type of admission, and presence of comorbidities (P = .008). The unadjusted percentage of deaths attributable to female sex was 13.9%, which decreased to 0.3% when adjusted for infection. Of the excess deaths in women, 96% could be accounted for by the differential distribution of infection between the sexes. The increased risk of mortality after CABG surgery in women may be explained by underlying differences in the prevalence of infection among men and women.

The rodlet cells of teleostean fish: their potential role in host defence in relation to the role of mast cells/eosinophilic granule cells

The distribution and potential function of the rodlet cells of teleosts were studied by microscopic observations on tissue samples from the digestive tract and adjacent tissues, including the bulbus arteriosus. Fish representing 3–5 genera from each of the families Salmonidae, Cyprinidae, Gadidae and Labridae were included in the study. Great individual variations in the distribution of rodlet cells were found in all species of salmonids, gadids and labrids. The cells seemed to be absent in some individuals of a species and were associated with different epithelial tissues in others, but were not found in vascular endothelia. Their occurrence was common in all salmonids caught in their natural environment, whereas those in aquaculture, kept under controlled conditions with respect to water quality, showed extremely few rodlet cells. In species of the cyprinid family, the picture was different. Rodlet cells were consistently present under the endothelium of the bulbus arteriosus, and were very numerous at this location in individuals infected with blood flukes. In other epithelial tissues of cyprinids, rodlet cells were encountered in fairly high numbers, but in some tissues of individuals from all species they were occasionally absent. In all of the studied families rodlet cells seemed to be recruited when helminths affected epithelial tissues. Mast cells/eosinophilic granule cells were consistently very numerous in tissues of the intestine of cyprinids and labrids. In gadids, mast cells/eosinophilic granule cells seemed to be absent. Present evidence points to a role for the rodlet cells in defence functions, e.g. in combating helminths, and the suggestion earlier made for mast cells/eosinophilic granule cells, that evolution has created a “standing force” in particular tissues of teleosts consistently exposed to pathogens, whereas an efficient “mobilization force” has been an advantage in those living in more pathogen-free environments, may also be applied to rodlet cells, explaining the differences between teleostean families with respect to their distribution pattern.

Distinguishing malignant from normal stomach tissues and its in vivo, in situ measurement in operating process using FTIR Fiber-Optic techniques

Gastric tissue samples were studied using mid-IR fiber-optic attenuated total reflectance (ATR) spectroscopy. FTIR spectra of 90 tissue samples from 48 patients, including 32 normal and 58 malignant tissue samples, were chosen as examples. Malignancy was usually characterized by the absence of CH and C=O bands, a weak amide II band near 1545 cm-1, a shift of the amide I band to lower wave number, a decrease in the ∼1450 cm-1 peak to less than the ∼ 1400 cm-1 peak. Subtraction spectra indicate that the amide I and amide II bands of normal and malignant tissues have larger differences in peak positions and relative intensities. The statistical analysis results confirm this conclusion. The results indicate that FTIR fiber optic techniques provide important information about cancerous tissue of the stomach, which can be used to differentiate the malignant tissue from the normal tissue. Based on the above results we successfully realize the detection of the tumor tissues of digestive tract in vivo and in situ. And the results of detection cancer near operating room and in vivo and in situ in the operating room are consistent with the conclusions for the samples stored in liquid N2, which is the basis for the clinical application.

Étude descriptive des bactériémies dans un hôpital gériatrique universitaire

Objectives. - To describe clinical features, microbiologic characteristics and outcome of bacteremia in the elderly patients hospitalized in a geriatric hospital. Patients and methods. - All episodes of bacteremia diagnosed from January 1 st to December 31 st 1998 were analysed, excluding false-positive cases due to skin contamination. The hospital comprises 1084 geriatric beds distributed as 111 in acute care (ACF), 333 in rehabilitation and intermediate-care (RICF), and 516 in long-term-care facilities (LTCF). Results. - Sixty-six episodes of bacteremia were observed in 65 patients. Among them 59 (89%) were nosocomial bacteremia distributed as 20 in ACF, 29 in RICF and 10 in LTCF (rates of 0.6, 0.35, and 0.05 episodes per 1000 patient-days, respectively.). Escherichia coli and Staphylococcus aureus were the main bacterial species involved in 31% and 28% of the cases, respectively. E. coli strains were 50% resistant to amoxicillin and 41% resistant to co-amoxiclav, and 68% of S. aureus strains were resistant to methicillin. Portals of entry were urinary tract (44%), respiratory tract (14%), digestive tract (11%), and soft tissue (8%). The same bacterial strain as in bacteremia was isolated from a peripheric site in 30 cases (47%), most of them being urines. For 15% cases, portal of entry cannot be determined. Mortality associated to nosocomial bacteremia was 25%, and death was significantly associated to MRSA, urinary or intravascular devices, chronic wounds and inappropriate antibiotic prescription. Conclusion. - In geriatric hospitals, bacteremia are mainly nosocomial cases. Prevention should focus on indwelling devices and antibiotic resistance.

Genetic characterization of a polymorphic dipeptidyl aminopeptidase of Apis mellifera

Dipeptidyl aminopeptidase (DAP) activity towards L-leucylglycine-β-naphthylamide (Leu-Gly NA) was characterized in pupae and adult extracts of Apis mellifera. Enzyme activity was more conspicuous in pupae than in adult extracts and it seemed to be concentrated in digestive tract tissues. Two genetically determined electrophoretic variants were observed in honeybee samples from the USA and Chile; in Brazilian Africanized bees, two additional variants were observed. Segregational analyses showed no close linkage between Dap and Est-1, Lap D, Pgm-1, cd, and Ac loci of Apis mellifera. dipeptydil aminopeptidase / genetic variation / developmental distribution / tissue distribution / Apis mellifera

A STUDY ON THE FEEDING ECOLOGY OF CHITONS USING ANALYSIS OF GUT CONTENTS AND FATTY ACID MARKERS

Diet composition and food sources of five species of chiton coexisting in the same biotope on a rockyboulder reef were studied using a combination of two methods: gut contents analysis and analysis of marker fatty acids composition in the digestive tract tissue. Despite the common food supply, there was considerable interspecific selection in consumption. In the gut contents of Ischnochiton hakodadensis, Tonicella granulata and Mopalia retifera, diatoms as well as fragments of red calcareous algae (Corallinaceae) and other macrophytes dominated. Harpacticoid and amphipod crustaceans were most frequent in the digestive tract of the chiton Placiphorella borealijaponica. The meiobenthic prey of Lepidozona albrechti was mostly harpacticoids, nematodes, ostracods, acarins and foraminiferans. In large L. albrechti, juvenile cirripedes constituted up to 95% of the gut contents. For all the investigated chitons, the fatty acid composition of total lipids in the digestive tract was determined for the first time. The species I. hakodadensis, T. granulata and M. retifera were characterized by a 16:0/16:1n-7 ratio � 1 and an 18:1n-9/18:1n-7 ratio � 1 along with a low content of the acid 22:6n-3. In contrast, the content of the acid 22:6n-3 in the lipids of the other two chiton species (L. albrechti and P. borealijaponica) was higher and the 16:0/16:1n-7 ratio � 1 and the 18:1n-9/18:1n-7 ratio � 1. The marker fatty acid distributions suggested that diatoms prevailed in the diet of I. hakodadensis, T. granulata and M. retifera, i.e. the three chiton species were mainly herbivorous. This was in agreement with the gut content data, and differentiated them from the other two chitons L. albrechti and P. borealijaponica which were carnivorous, as indicated by analysis of both marker fatty acid composition and gut contents. The share of macrophytes and insignificant bacterial contribution to the chiton diets as well as the possibility of shifts in the feeding strategy of chitons were discussed.

A Predominant Role of Acyl-CoA:monoacylglycerol Acyltransferase-2 in Dietary Fat Absorption Implicated by Tissue Distribution, Subcellular Localization, and Up-regulation by High Fat Diet

Acyl-CoA:monoacylglycerol acyltransferase-2 (MGAT2) catalyzes the synthesis of diacylglycerol and differs from the MGAT1 and MGAT3 in tissue distribution at the mRNA level. In addition to the small intestine, MGAT2 mRNA is also expressed at high levels in human liver, the lower gastrointestinal tract, and the mouse kidney, but the physiological significance of such expression has not yet been studied. Using an affinity-purified antibody, the present study investigated the expression of murine MGAT2 protein along the intestinal tract, determined its subcellular localization, and studied its regulation by diet and in db/db mouse. Results demonstrate a high level of MGAT2 expression in the small intestine in a proximal-to-distal gradient that correlated well with both MGAT enzyme activity and fat absorption pattern. In contrast, MGAT2 protein was not detectable in other sections of the digestive tract, including stomach, cecum, colon, and rectum, or other mouse tissues such as kidney, liver, and adipocytes. Immunohistological studies provided direct evidence that the enzyme is expressed not only in the villi, but also in the crypt regions of the small intestine, which suggests that MGAT2 expression occurs prior to the maturation of enterocytes. MGAT2 is localized in the endoplasmic reticulum (ER) in both MGAT2-transfected COS-7 and Caco-2 cells, indicating that the ER is the primary site for dietary fat re-synthesis. MGAT2 expression appeared not to be affected by diabetes in the db/db mouse, however, the total intestinal MGAT activity was significantly enhanced. Finally, an up-regulation of both MGAT2 protein expression and MGAT activity was observed in mice fed a high fat diet, implicating a role of MGAT2 in diet-induced obesity. Taken together, our data suggest a predominant role of MGAT2 in dietary fat absorption.

Intermittent fasting during winter and spring affects body composition and reproduction of a migratory duck

We compared food intake, body mass and body composition of male and female black ducks (Anas rubripes) during winter (January-March). Birds were fed the same complete diet ad libitum on consecutive days each week without fasting (control; nine male; nine female) or with either short fasts (2 day x week(-1); nine male; nine female), or long fasts (4 day x week(-1); eleven male; twelve female). We continued treatments through spring (March-May) to measure the effect of intermittent fasts on body mass and egg production. Daily food intake of fasted birds was up to four times that of unfasted birds. Weekly food intake of males was similar among treatments (364 g x kg(-1) x week(-1)) but fasted females consumed more than unfasted females in January (363 g x kg(-1) x week(-1) vs. 225 g x kg(-1) x week(-1)). Although both sexes lost 10-14% body mass, fasted females lost less mass and lipid than unfasted females during winter. Total body nitrogen was conserved over winter in both sexes even though the heart and spleen lost mass while the reproductive tract and liver gained mass. Intermittent fasting increased liver, intestinal tissue and digesta mass of females but not of males. Fasting delayed egg production in spring but did not affect size, fertility or hatching of the clutch. Females on long fasts were still heavier than controls after laying eggs. Thus black ducks combine flexibility of food intake with plasticity of digestive tract, liver and adipose tissue when food supply is interrupted during winter. Females modulate body mass for survival and defer reproduction when food supply is interrupted in spring.

Localization of Zn-binding protein in the digestive tract tissue of common carp

: The concentrations of Zn and sulfhydryl (SH) groups in the digestive tract tissue of common carp and some aquatic animals were studied. It was found that Zn and bound SH groups could be used as indicators for detecting the Zn-binding protein in the digestive tract tissue of common carp. The digestive tract tissue of the fish underwent subcellular fractionation, and it was found that the nuclei/cell debris fraction contained most of the DNA (85%), Na+/K+-ATPase (82%), organic phosphate (90%) and the Zn-binding protein (79%), but only part of the 5′-nucletidase and alkaline phosphatase (<23%). The nuclei/cell debris fraction of the digestive tract tissue of common carp was treated with either collagenase type I or type IV, and subfractionated by sucrose density centrifugation. It was found that treatment with collagenase type IV could release more than 50% of the Zn-binding protein, Na+/K+-ATPase and organic phosphate from collagen. Sections of digestive tract tissue of common carp were stained for Zn. It was observed that Zn can be found mainly on the edge of the epithelial layer, and everywhere in the ‘membrane-like’ portion of the submucosal and muscular layers. It is proposed that most of the Zn-binding protein in the digestive tract tissue of common carp is located on the basolateral plasma membranes of the epithelial cells and on the surrounding muscle cells that are attached to the collagen type IV of basal laminae.

High Zn concentration in the digestive tract tissues of common carp &lt;i&gt;cyprinus carpio&lt;/i&gt;

High Zn concentration in the digestive tract tissues of common carp &lt;i&gt;cyprinus carpio&lt;/i&gt;

Metal levels in eviscerated tissue of shallow-water deposit-feeding holothurians

Concentrations of six metals (Al, Cu, Mn, Ni, Pb, Zn) were determined in eviscerated digestive tract tissues of the sedimentivorous holothurians Holothuria mexicana and Isostichopus badionotus from 28 stations in the Morrocoy National Park (MNP), Venezuela. Eviscerated tissues of large individuals of both species (contracted length ≥20 and 15 cm, respectively) exhibited significantly higher metal concentrations than small individuals at the two biotopes under study. In comparison with the adjoining sediments, the holothurians enriched Cu, Ni, Pb and Zn. Concentrations of metals in small specimens (CL ≤10 cm) of I. badionotus tissues were higher than in H. mexicana (CL ≤15). Mean concentrations of Cu, Pb and Ni in H. mexicana and I. badionotus tissues were higher than reported values for other resident marine invertebrates in the MNP, as well as deep-sea holothurians, and also exceeded legal reference and maximum recommended values. This study hints that holothurians, which in this project have shown their potential as biomonitors, may provide a pathway to several metals for transfer from mangrove sediments. These metals might pose ex situ public health risks, since a sporadic furtive fishery of holothurians is currently under way in the study area for export to Far East markets.

T lymphocyte and fibroblast interactions: the case of skin involvement in systemic sclerosis and other examples.

Morphogenesis, tissue repair, and wound healing are accomplished through regulated metabolic changes which occur at both stromal and parenchymal levels. Resident or newly recruited fibroblasts are directly responsible for the synthesis of the extracellular matrix (ECM), and consequently for the optimal composition of the stroma. The balance between ECM synthesis and degradation by fibroblasts needs to be finely tuned to maintain the physiological characteristics of involved tissues. The interplay between fibroblasts and chemotactically recruited inflammatory cells controls this balance. In fibrotic processes, any abnormality in this controlled interplay may result in excessive and altered ECM deposition. Although the events leading to fibrosis might be different in different pathological events and characteristic of each disease or of each organ, in the majority of the cases inflammatory cells of hematopoietic origin play an essential role in the regulatory processes and may be responsible for dysregulated ECM deposition. The aim of this review is the analysis of the role of T cells in the regulation/dysregulation of ECM metabolism by fibroblasts. Recent progress made in this area of research has shown that the relationship between T cells and fibroblasts is highly dynamic. In this context, it is important to recognize that T cells characteristically considered as belonging to the adaptive arm, may nevertheless act, in some conditions, as cells of the innate arm of the immune system and deliver regulatory signals with no need for specific antigen recognition. The disease model which is characterized by varying degrees of fibrosis involving the skin, lung, digestive tract and other tissues, and which we will use for most of this discussion, is systemic sclerosis (SSc), also known as scleroderma.

Zinc and zinc binding substances in the tissues of common carp

Extraordinarily high concentrations of zinc (300–500 μg/(g fresh tissue)) are often found in the digestive tract tissue of common carp Cyprinus carpio, and high zinc concentrations (typically >100 μg/(g fresh tissue)) are also found in the kidney, gill, skeletal tissues, and spleen. In the present study, we found that only about 40% of the zinc in the digestive tract tissue of common carp could be extracted by water. However, 0.01 M citrate buffer, pH 6.2 could extract over 90% of the zinc. Subcellular zinc distribution in the tissues of common carp, grass carp Ctenopharyngodon idellus, silver carp Aristichthys nobilis, and tilapia Oreochromis aureus were compared. It was found that zinc concentrations in the cytosol, microsomal and mitochondrial fractions were approximately the same for all four species, being only about 16, 5, and 4 μg/(g fresh tissue), respectively. However, zinc concentrations in the nuclei/cell debris fraction of common carp tissue were much higher (46–370 μg/(g fresh tissue)) than the <14 μg/(g fresh tissue) found in the other three species. From this we conclude that neither water-soluble zinc proteins nor metallothionein could account for the high levels of zinc found in common carp tissues. A preliminary biochemical investigation suggests that the main zinc binding substance(s) in the nuclei/cell debris fraction of digestive tract tissue of common carp was probably a membrane protein(s).

Cloning and Identification of the Gene Gob-5, Which Is Expressed in Intestinal Goblet Cells in Mice

By using the large-scalein situhybridization system (Analytical Biochemistry(1997) 254, 23–30), we isolated the cDNA gob-5, which is expressed in the intestinal goblet cells in mice. The transcript was also found to be abundantly expressed in small intestine, colon, stomach, and uterus and slightly expressed in trachea tissue. The gob-5 cDNA was shown to be 3 kb in size. After screening digestive tract tissues using ourin situhybridization method we demonstrate that gob-5 is expressed in mucous cells. The deduced amino acid sequence is similar to the gene which encodes the epithelial chloride channel in the bovine trachea.