Immunohistochemical observations of the endocrine pancreas during metamorphosis of the sea lamprey,Petromyzon marinus L.

Summary Light-microscopic immunohistochemistry was used to localize insulin- and somatostatin-immunoreactive cells within developing endocrine pancreatic tissue of metamorphosing lampreys, Petromyzon marinus. The extrahepatic common bile duct and a portion of the intrahepatic bile duct develop into the caudal portion of the endocrine pancreas. The cranial pancreas is composed of follicles originating in the intestinal and diverticular epithelia, thus following the method of formation of pancreatic follicles from gut epithelium in larvae. In both the cranial and caudal portions, and in an intermediate cord of isolated follicles which connect these two major masses, insulin-immunoreactive cells appear first and are followed by cells showing somatostatin-immunoreactivity. In all stages of metamorphosis individual endocrine cells demonstrate immunoreactivity to a single hormone. Biliary atresia in lamprey may have some adaptive significance in providing cells that produce a caudal endocrine pancreas.Supported by NSERC of Canada grant No. A5945 and MRC of Canada grant No. MA8629 to JHY     

Effect of acetaminophen on hepatic content and biliary efflux of glutathione disulfide in mice

The increased expiration of ethane and pentane by mice treated with hepatotoxic doses of acetaminophen suggests the possibility of oxidant mechanisms associated with the necrosis. However, studies in rats are not consistent with oxidant stress mechanisms causing the damage, because acetaminophen given to rats does not increase GSSG efflux, a sensitive index of intrahepatic oxidant stress. To compare the extent of oxidant stress generated by acetaminophen in mice versus rats, hepatic content and biliary efflux of GSSG and GSH in mice have been examined. Bile was collected from anesthetized male ICR mice before and after intraperitoneal administration of acetaminophen (325 mg/kg, 2.15 mmol/kg), t-butyl hydroperoxide (TBHP) (1.5 mmol/kg), diethyl maleate (400 mg/kg, 2.33 mmol/kg, in corn oil) or saline (control) and GSH and GSSG were measured by the enzymatic recycling method of Tietze. An increase in biliary GSSG efflux was produced by t-butyl hydroperoxide, but not by the other agents. Biliary GSH/GSSG ratios decreased in acetaminophen-treated animals, presumably reflecting the marked depletion of hepatic GSH, since a similar decrease was observed with non-hepatotoxic doses of diethyl maleate. The failure of acetaminophen to increase the hepatic content or biliary efflux of GSSG in ICR mice is not consistent with the view that oxidant stress mechanisms cause the damage, despite the increases in alkanes expired after acetaminophen administration in this specific animal model.     

Mathematical modelling of runoff and material transport from drainage areas into recipient water bodies

This paper describes a set of mathematical models to calculate runoff, soil erosion and chemical substance yields for drainage areas. The models represent different degrees of complexity and details of describing hydrological and hydrochemical processes. The availability of initial information and the requirements of the task determine the choice of a model for each particular case. These models have been written as PC/AT programs, to enable their use by a wide range of specialists. The models have been tested in different physical and geographical conditions, e.g. in some small watersheds on the Karelian Isthmus, west of Lake Ladoga, and in experimental catchment areas located in the Valdai Hills area in the southern part of Lake Ladoga drainage area. In further applications the drainage area models have been combined with models of the recipient water body, to obtain a single model of a watershed-lake system. The results of tests have proved that the models can be used for evaluation, simulation and forecasting of the processes of rainfall and snowmelt runoff, infiltration, evaporation, water erosion and pollutant wash-off from drainage areas.     

Salmonella typhimurium acrB-like gene: identification and role in resistance to biliary salts and detergents and in murine infection

Abstract Salmonella serotype typhimurium transpositional mutants altered in resistance to biliary salts and detergents were isolated previously. We have characterized further the LX1054 mutant strain, the most sensitive of them. The chromosomal DNA segment flanking transposon insertion was cloned and sequenced. The highest level of identity was found for the acrB (formerly acrE ) gene of Escherichia coli , a gene encoding a drug efflux pump of the Acr family. LX1054 exhibited a reduced capacity to colonize the intestinal tract. After passages in mice, the mutant strain lost the sensitive phenotype. In vitro, a resumption of growth appeared after 17 h of culture in medium with cholate or other tested biological or chemical detergents. Then, the acquired resistant phenotype seemed stable. The data suggested a role of S. typhimurium acrB -like gene in resistance to biliary salts and detergents and in mice intestinal colonization. However, the local and transient sensitivity observed in vivo, and the in vitro adaptations suggest that several detergent-resistance mechanisms operate in S. typhimurium .     

Four fish species new to the Omo-Turkana basin,with comments on the distribution ofNemacheilus abyssinicus (Cypriniformes: Balitoridae) in Ethiopia

Four fish species,Pollimyrus isidori (Mormyridae),Barbus paludinosus, Labeo forskalii (Cyprinidae), andNemacheilus abyssinicus (Balitoridae), new to the Omo-Turkana basin, were recorded from the Gojeb River, a tributary of the Omo River (south-western Ethiopia). Occurrence of the latter species in the upper reaches of the Blue Nile and of the Omo drainage substantiates the belonging of the upper parts of these water systems to the Abyssinian highlands ichthyofaunal province.     

Estimating regional carbon stocks and spatially covarying edaphic factors using soil maps at three scales

Most estimates of regional and global soil carbon stocks are based on extrapolations of mean soil C contents for broad categories of soil or vegetation types. Uncertainties exist in both the estimates of mean soil C contents and the area over which each mean should be extrapolated. Geographic information systems now permit spatially referenced estimates of soil C at finer scales of resolution than were previously practical. We compared estimates of total soil C stocks of the state of Maine using three methods: (1) multiplying the area of the state by published means of soil C for temperate forests and for Spodosols; (2) calculating areas of inclusions of soil taxa in the 1:5,000,000 FAO/UNESCO Soils Map of the World and multiplying those areas by selected mean carbon contents; and (3) calculating soil C for each soil series and map unit in the 1:250,000 State Soil Geographic Data Base (STATSGO) and summing these estimates for the entire state. The STATSGO estimate of total soil C was between 23% and 49% higher than the common coarse scale extrapolations, primarily because STATSGO included data on Histosols, which cover less than 5% of the area of the state, but which constitute over one-third of the soil C. Spodosols cover about 65% of the state, but contribute less than 39% of the soil C. Estimates of total soil C in Maine based on the FAO map agreed within 8% of the STATSGO estimate for one possible matching of FAO soil taxa with data on soil C, but another plausible matching overestimated soil C stocks. We also compared estimates from the 1:250,000 STATSGO database and from the 1:20,000 Soil Survey Geographic Data Base (SSURGO) for a 7.5 minute quadrangle within the state. SSURGO indicated 13% less total soil C than did STATSGO, largely because the attribute data on depths of soil horizons in SSURGO are more specific for this locality. Despite localized differences, the STATSGO database offers promise of scaling up county soil survey data to regional scales because it includes attribute data and estimates of areal coverage of C-rich inclusions within map units. The spatially referenced data also permit examination of covariation of soil C stocks with soil properties thought to affect stabilization of soil C. Clay content was a poor predictor of soil C in Maine, but drainage class covaried significantly with soil C across the state.     

Reducing acidic discharges from coastal wetlands in eastern Australia

Much of eastern Australia's coastal lowlands are underlain by Holocene sulfidic sediments. Large areas have been drained for agriculture. Drained, sulfidic sediments oxidize and produce highly acidic discharge (pH<4) with significant impacts on estuarine ecosystems. The rate of production of acid from drained floodplains is between 100 to 300 kg H₂SO₄ /ha/y and hundreds of tonnes of H₂SO₄ can be discharged in a single flood from the floodplain. Generation and export of acidity is controlled by the water balance of the floodplain, the characteristics of the drainage system and the distribution of sulfides. Evapotranspiration by native plants and crops plays a dominant role in the oxidation of sediments in dry periods. In wet periods, upland discharges to floodplains dominate the water balance. Drain spacing and drain depth are critical factors in the export of acidity into coastal streams. Amelioration of acidic outflows requires an understanding of the interaction between chemical and hydrological processes in sulfidic landscapes. Redesign of drainage systems to manage surface waters and reduce drain density with the treatment of drains with lime offer promise for treating acidic discharge and reducing impacts. Reflooding of drained, partially oxidized floodplains with freshwater may not be a panacea because of the large volumes of acid stored in the soil, a lack of labile organic matter in the sediments needed to reduce sulfate and irreversible changes to the soil due to oxidation. Tidal brackish water reflooding of unproductive acidified lowlands offers promise for rehabilitating wetlands. Sulfidic wetlands which are still undrained should remain so unless all acidic discharge can be treated.     

Fluctuations of the soil environment and fine root growth in a young Sitka spruce plantation

Summary From soil cores extracted at 5 day intervals from 3 May to 6 August it was found that the biomass of fine roots in a Sitka spruce plantation, 14 years old, fluctuated with maxima in late May and mid July. The earlier peak coincides with increasing soil temperatures during a period of high incident precipitation and the latter developed when the soil profile was rewetted. Fine root biomass and soil moisture tension (SMT) were significantly and negatively correlated in three of four soil horizons. Root mortality occurred whenever incident precipitation failed to maintain soil moisture tension near zero. In the very open pored horizons the critical SMT for root death was unexpected small, <0.1 bars; in the peat horizons it wasc 0.2 bars.     

A scanning electron microscopic study of the liver of the monkey Macaca speciosa

Summary The bile canalicular network of the monkey was studied by fracturing fixed liver tissue and examination by scanning electron microscopy. Bile canaliculi do not differ remarkably from those described in other species. Their course and luminal diameter vary, depending on their position in the liver lobule. In one specimen the continuity of a canaliculus with a terminal bile ductule (canal of Hering) is presented. Several constrictions occur in this part of the ductular lumen. The interlobular bile duct wall shows two kinds of niches. A single cilium arises from a primary niche. The walls of secondary niches contain numerous primary niches. Simple columnar epithelium lines the common bile duct, the main pancreatic duct and the gallbladder. A common feature is the presence of microplicae on their lateral cell surfaces.

---

Zusammenfassung Das Netzwerk der Gallekanälchen beim Affen wird durch Brechen von fixiertem Lebergewebe sichtbar. Strukturen der Portalfelder und der extrahepatischen Gänge werden durch Schneiden von Gewebe dargestellt. DieGallekanälchenunterscheidensichnichtwesentlich von den bei anderen Spezies beschriebenen. Ihr unterschiedlicher Verlauf und Lumendurchmesser hängen von ihrer intralobulären Lage ab. Die Kontinuität eines Gallekanälchens mit einem Ductulus (Heringscher Kanal) wird in einem Fall dargestellt. Im ductulären Lumen kommen mehrere Konstriktionen vor. Die Wand der interlobulären Gallengänge weist zwei Arten von Nischen auf. Eine Einzelzilie kommt aus den primären Nischen. Sekundäre Nischen bestehen aus mehreren primären Nischen. Einschichtiges hochprismatisches Epithel kleidet den Ductus choledochus, den Ductus pancreaticus und die Gallenblase aus. Ein gemeinsames Merkmal ihrer lateralen Zelloberflächen sind Mikroplicae.

     

Tissue distribution,metabolism, and elimination of perfluorooctanoic acid in male and female rats

The elimination, tissue distribution, and metabolism of [1-¹⁴C]perfluorooctanoic acid (PFOA) was examined in male and female rats for 28 days after a single ip dose (9.4 μmol/kg, 4 mg/kg). A sex difference in urinary elimination of PFOA-derived ¹⁴C was observed. Female rats eliminated PFOA-derived radioactivity rapidly in the urine with 91% of the dose being excreted in the first 24 hr. In the same period, male rats eliminated only 6% of the administered ¹⁴C in the urine. The sex-related difference in urinary elimination resulted in the observed difference in the whole-body elimination half-life (t_1/2) of PFOA in males (t_1/2 = 15 days) and females (t_1/2 < 1 day). Analysis of PFOA-derived ¹⁴C in tissues showed that the liver and plasma of male rats and the liver, plasma, and kidney of female rats were the primary tissues of distribution. The relatively high concentration of PFOA in the male liver was further examined using an in situ nonrecirculating liver perfusion technique. It was shown that 11% of the PFOA infused was extracted by the liver in a single pass. The ability of the liver to eliminate PFOA into bile was examined in rats whose renal pedicles were ligated to alleviate sex differences in the urinary excretion of PFOA. In a 6-hr period following IP administration of PFOA, there was no apparent difference in biliary excretion, where both males and females eliminated less than 1% of the PFOA dose via this route. We hypothesized that the sex difference in the persistence of PFOA was due to a more rapid formation of a PFOA-containing lipid (i.e., a PFOA-containing mono-, di-, or triacylglycerol, cholesteryl ester, methyl ester, or phospholipid) in the male rat. Also, the increased urinary elimination of PFOA in females may have been due to increased metabolism to a PFOA-glucuronide or sulfate ester. However, no evidence that PFOA is conjugated to form a persistent hybrid lipid was obtained, nor were polar metabolites of PFOA in urine or bile detected. In addition, daily urinary excretion of fluoride in male and female rats before or after PFOA treatment were similar, suggesting that the parent compound is not defluorinated. Thus, the more rapid elimination of PFOA from female rats is not due to formation of a PFOA metabolite.