Intestinal length of three California pinniped species

Forty-eight intestinal tracts, extracted from both sexes of California sea lions, Harbour seals and Northern elephant seals, were measured. The majority of intestinal tracts were removed from stranded animals that died from various causes. The sea lions and elephant seals, approximately equal in size, were larger than the Harbour seals. All species possess a small intestine which is significantly longer than even the entire gastrointestinal tract of herbivores of comparable size. Elephant seal small intestines, averaging approximately 25 times the seal's body length, were considerably longer than the small intestines of either sea lions (averaged more than 18 times the body length) or Harbour seals (averaged nearly 16 times the body length). However, the large intestines of elephant seals were shorter than either of the other two species. Among the sea lions and Harbour seals the large intestines were approximately equal in length. Sea lions and Harbour seals also showed a close correlation between standard length and total intestinal length. Among elephant seals these two parameters showed greater variability. The functional significance of the extremely long small intestine remains unclear. Certainly, the large body mass and high energy requirements of these animals has contributed to the development of a long intestinal tract. It also appears likely that diet and the high motility rate of digesta influenced the intestinal development. Comparatively, the significantly shorter large intestine of elephant seals probably relates to this species' remarkable capabilities in water conservation and metabolic water retention.     

Histological,histochemical, and ultrastructural investigations on the gastrointestinal system of antarctic seals: Weddell seal (Leptonychotes weddellii) and crabeater seal (Lobodon carcinophagus)

The morphology of the principal sections of the gastrointestinal system of two Antarctic seals with different dietary habits, namely, the Weddell seal (Leptonychotes weddellii) and the crabeater seal (Lobodon carcinophagus), has been investigated. Histologically examined by light microscopy, the tissue layers of the gastrointestinal tract of both seals are almost identical to those observed in most other mammals and no major differences in principle organization could be found between the two seal species. The ultrastructure of the gastric and intestinal epithelial cells has been examined and is also closely comparable to that of these cells in other mammals; however, Paneth cells have not been found in our material. In general, therefore, adaptations of the gastrointestinal tract to the aquatic environment or the diet are not obvious at the morphological levels of organization studied. Histochemical differences are found between the two closely related species; mucins of the surface epithelium in the stomach of Weddell seals are highly sulfated, while those in the crabeater seal are not. Mucous neck cells in Weddell seals contain acid mucosubstances, while those of crabeater seals contain neutral ones. Goblet cells in the small and large intestine in Weddell seals contain both neutral and acid mucosubstances. Both mucin types are detected in the crabeater seal; however, the mucins of the colon in the crabeater seal are more highly sulfated than those in the Weddell seal. The ratio of globet cells to enterocytes in the large intestine of crabeater seals is higher than that in Weddell seals. © 1995 Wiley-Liss, Inc.     

Adenosine 3' , 5'-cyclic monophsphate phosphodiesterase activities in the x-irradiation induced rat small bowel adenocarcinoma.

The adenosine 3′, 5′-cyclic monophosphate phosphodiesterase (PDE) activities were evaluated in X-irradiation induced Holtzman rat small bowell adenocarcinoma and age-matched normal small intestine. Within normal small intestine, PDE activity was optimal at pH 7.4, and highly dependent upon the addition of Mg²⁺ or Mn²⁺. Analyses of the rat small bowel adenocarcinoma revealed significantly elevated PDE activities above the normal small bowel which were found to be relatively constant throughout the length of the ileum and jejunum. These findings suggest that the diminished intracellular adenosine 3′, 5′-cyclic monophosphate levels observed in this lesion (1) may be the consequence of elevated PDE activities.     

尾斑瘰螈主要消化器官组织结构观察

本研究采用组织学方法对尾斑瘰螈(Paramesotriton caudopunctatus)的消化器官进行了显微结构观察。结果表明,尾斑瘰螈食管较短,胃、肠壁组织结构分为黏膜层、黏膜下层、肌层和外膜,小肠前段的黏膜下层缺失。胃黏膜层中有许多胃腺,胃腺细胞胞质含嗜酸性颗粒。小肠前段绒毛细长密集,中段、后段逐渐短小稀疏,在黏膜层的固有膜中没有肠腺分布。肝实质中肝小叶界限不明显,肝小叶内有大量色素颗粒成团分布。     

Corynosoma magdaleni in gray seals from the Gulf of Bothnia,with emended descriptions of Corynosoma strumosum and Corynosoma magdaleni

Because of the likelihood that Corynosoma magdaleni Montreuil, 1958. has been confused with C. strumosum (Rudolphi, 1802) in reports of parasites from seals and to clarify its distribution in the Baltic Sea, acanthocephalans from 26 young gray seals from the southwestern Finnish archipelago (western Baltic Sea) were examined. All harbored C. semerme (Forssell. 1904). In addition to C. semerme, 12 had both C. strumosum and C. magdaleni, 3 had only C. strumosum, and 9 had only C. magdaleni. Most anatomical structures of C. strumosum are similar to, but larger than, those of C. magdaleni. The most conspicuous differences are the longer and more robust trunk of C. strumosum, the routinely longer proboscis (mean, 653 vs. 476 microm) and larger proboscis hook (mean, 69 vs. 58 microm) of C. strumosum, and the greater extent of ventral trunk spines (mean, 61 vs. 47%) in C. magdaleni. In addition, C. strumosum consistently possesses 18 longitudinal rows of proboscis hooks, whereas C. magdaleni has 17-23, with 20 being the usual number by far. In seals aged 3.6 mo, on average, C. strumosum was more prevalent and abundant than was C. magdaleni, whereas in seals of age 2.0-3.0 mo the reverse was true, with C. strumosum being nearly absent. These differences might reveal the age-dependent food habits of the very young seals. No site segregation was found between C. strumosum and C. magdaleni in the small intestine, but they clearly segregated from C. semerme, which occurred mainly in the cecum, large intestine, and rectum. All species matured equally well in gray seals, with 62, 67, and 53% of the C. magdaleni, C. strumosum, and C. semerme, respectively, comprising gravid worms (possessing eggs with fully formed acanthors).     

Food transit times in captive leopard seals (Hydrurga leptonyx)

The passage rate of food through the alimentary tract of three captive, female leopard seals (Hydrurga leptonyx) was assessed. Seals were housed during winter in holding pools with access to water to reduce factors affecting digestion. Three different marker types were used; large and small beads and TiO₂. Animals were checked hourly, and sample collections continued for 270 h after dosing. Individual differences in transit and mean retention times were observed, possibly reflecting inter-digestive emptying times of the stomach and small intestine. Age differences and activity levels may also have been a factor. Leopard seals displayed extended food transit times similar to terrestrial carnivores instead of other pinnipeds. This result suggests an adaptation of digestive system to cope with the opportunistic diet and range of prey types consumed.     

Gross anatomy of the gastrointestinal system of harp seals (Phoca groenlandica)

The gross anatomy of the gastrointestinal system of 12 harp seals ( Phoca groenlandica ) was investigated. Harp seals have a typical carnivore monogastric stomach. The tissue wet weight of the stomach of harp seals represented 27.01 (S.D. 3.99)% ( n = 12) of the total gastrointestinal tract (GI-tract). All animals were killed while resting on the ice, and had empty stomachs, but when expanded with water to a 30cm pressure the stomach contained 0.60 to 1.60 litres, representing 1.00 (S.D. 0.26)% ( n = 12) of the body mass. The small intestine ranged in length from 20.44 to 25.32m, being 14.36 (S.D. 1.58) times the body length, and the tissue wet weight constituted 67.61 (S.D. 4.55)% of the total GI-tract ( n = 12). Both caecum and colon were short, maximally 5 and 78 cm, respectively, being 0.022 (S.D. 0.005) and 0.38 (S.D. 0.06) times the body length ( n = 12). The caecum tissue wet weight was only 0.18 (S.D. 0.04)% of the total GI-tract weight, while the colon tissue wet weight contributed to 5.33 (S.D. 1.19)% ( n = 12). It is concluded that harp seals have relatively long intestines compared to minke whales eating a comparable diet in the North Atlantic Ocean.     

Gut length, food transit time and diving habit in phocid seals

The southern elephant seal (Mirounga leonina) has the ability to dive for 2 h and reach depths of 1200 m. This creature is also exceptional in having a small intestine that is 25 times body length. Krockenberger and Bryden advanced the hypothesis that the long small intestine has developed to compensate for the extended periods with reduced or even abolished intestinal blood perfusion during diving. To test this hypothesis we have measured small-intestinal lengths in crabeater (Lobodon carcinophagus), Weddell (Leptonychotes weddellii), Ross (Ommatophoca rossi), leopard (Hydrurga leptonyx), harp (Phoca groenlandica), ringed (Phoca hispida) and hooded (Cystophora cristata) seals and related them to available data on their maximal dive duration. We found no significant correlation (P > 0.05) between intestinal length relative to body length and diving ability, but we found that small-intestinal internal area was significantly (P < 0.05) related to body length. A crude scanning electron microscopical examination of the small intestines of Weddell, crabeater, hooded and harp seals failed to reveal any gross anatomical differences between small-intestinal surfaces. This suggests that gut dimension in this variety of phocid species with widely differing diving ability is not related to diving habit, but is instead related to body size. The transit time of digesta was determined in two 1-year-old harp seals by use of radiopaque polyethylene rings of 4-mm diameter followed by X-ray examination, as markers for the solid phase passage, and chromium ethylene-diaminetetra acetic acid (Cr-EDTA) as a marker for the liquid phase. The transit time for the Cr-EDTA marker was 6.9 h ± 0.5 SE (range 4.5–8 h, n= 7), while 80% of the polyethylene markers appeared in the colon after 17.6 h ± 1.0 SE (range 14–21.5 h, n= 6) and were sometimes retained in the colon for several hours before defecation. These transit times did not change significantly (P > 0.05) in response to repetitive diving over a period of 8 h. This indicates that the often-used Cr-EDTA is not a good measure for digesta passage time when used alone in seals, and that the hypothesis of Krockenberger and Bryden is most likely wrong. Received: 17 December 1997 / Accepted: 4 May 1998     

Rate of passage of digesta through the alimentary tract of southern elephant seals (Mirounga leonina) (Carnivora: Phocidae)

The inert markers chromium-EDTA (liquid phase marker) and ytterbium nitrate (solid phase marker) were added to the food of three southern elephant seals in Taronga Zoo, Sydney, in a series of nine trials. The enclosures were checked at 15 to 30 minute intervals for up to 60 hours after dosing, and all faeces voided on land were collected (91 samples). Marker concentrations in faecal dry matter were determined and mean retention times calculated from the concentration-time curves.
The faeces were soft to semiliquid, with mean water content of 58% (range 24–80%). The marker concentration curves indicated a rapid rate of food transit through the gastro-intestinal tract in elephant seals compared with other carnivores. The mean time between dosing and first recovery of marker (Initial Recovery Time) was nine hours. This was significantly longer than the figure of 4.8 hours for northern elephant seals reported previously, and possible reasons for the differences are discussed. Mean Retention Time, a better index of rate of passage of ingesta, was 13 hours for the three southern elephant seals. This compares with times of 22 hours for the dog, 15 hours for the raccoon, and 13 hours for the cat, all carnivores with much shorter gastrointestinal tracts, both absolutely and relative to body size, than the southern elephant seal.
It is suggested that the very long small intestine may be an adaptation to foraging at depth, combined with long periods of submergence and the need to ingest large amounts of food when the animal is at sea continuously for weeks or months.     

Expression and localization of Muc4/sialomucin complex (SMC) in the adult and developing rat intestine: implications for Muc4/SMC function

Muc4/sialomucin complex (SMC) is a high molecular mass heterodimeric membrane mucin, encoded by a single gene, and originally discovered in a highly metastatic ascites rat mammary adenocarcinoma. Subsequent studies have shown that it is a prominent component of many accessible and vulnerable epithelia, including the gastrointestinal tract. Immunoblot and immunofluorescence analyses demonstrated that Muc4/SMC expression in the rat small intestine increases from proximal to distal regions and is located predominantly in cells at the base of the crypts. These cells were postulated to be Paneth cells, based on their location, morphology, and secretory granule content. Immunohistochemistry indicated the presence of Muc4/SMC in these granules. Muc4/SMC expression was higher in the rat colon than small intestine and was abundantly present in colonic goblet cells, but not in goblet cells in the small intestine. Immunohistochemistry also suggested the presence of MUC4 in human colonic goblet cells. Biochemical analyses indicated that rat colonic Muc4/SMC is primarily the soluble form of the membrane mucin. Analyses of Muc4/SMC during development of the rat gastrointestinal tract showed its appearance at embryonic day 14 of the esophagus and at day 15 at the surface of the undifferentiated stratified epithelium at the gastroduodenal junction, then later at cell surfaces in the more distal regions of the differentiated epithelium of the small intestine, culminating in expression as an intracellular form in the crypts of the small intestine at about day 21. Limited expression in the colon was observed during development before birth at cell surfaces, with expression as an intracellular form in the goblet cells arising during the second week after birth. These results suggest that membrane mucin Muc4/SMC serves different functions during development of the intestine in the rat, but is primarily a secreted product in the adult animal.     

Morphofunctional transformations of the blood vessels in the transplantation of syngeneic normal tissue and of a tumor

In 360 Fisher rats dynamics of changes in blood vessels, the microcirculatory bed vessels included, have been investigated. An original model of the experiment at implantation of syngenic tissues of the fetus normal intestine and tumorous adenocarcinoma of the small intestine has been used. Specific changes of the blood vessels have been revealed around and in the capsule of the implant, depending on their morphological reorganization. The blood vessels changes can serve as a prognostic sign of possible alterations in the implant structure.     

Habitat selection by ice-associated pinnipeds near St. Lawrence Island,Alaska in March 2001

Aerial surveys of ice-associated pinnipeds were conducted south of St. Lawrence Island in March 2001. The observed distributions of bearded seals (Erignathus barbatus), ribbon seals (Phoca fasciata), ringed seals (P. hispida), spotted seals (P. largha), and walruses (Odobenus rosmarus) were compared to the distributions of ice habitat types and benthic communities. Randomization tests were used to investigate habitat selection for each species. Both ringed seals and walruses preferred large ice floes (>48 m in diameter) that were common in the interior ice pack. Spotted seals favored smaller ice floes (<20 m in diameter) common near the ice edge, and bearded seals avoided large floes and preferred transitional habitat between small and large floes. Ringed seals also seemed to prefer areas with greater than 90% sea ice coverage, and bearded seals preferred 70–90% sea ice coverage while avoiding areas with greater than 90% coverage. All species, except spotted seals, were seen most frequently in a region of high benthic biomass, and randomization tests suggested that bearded seals actively selected that region.     

Summer diet of Weddell Seals (Leptonychotes weddelli) in the eastern and southern Weddell Sea,Antarctica

Summary Stomach and intestine samples from 21 adult Weddell seals were used to study the diet of these seals from the eastern and southern Weddell Sea coast from January to February 1983 and 1985. Fish occurred in all seals, squid in five, octopods in three and Euphausia crystallorophias in one seal. Pleuragramma antarcticum was the predominant fish in the diet, constituting 61.1% of otoliths in 1983 samples and 93.8% in 1985. Aethotaxis mitopteryx, Dissostichus mawsoni, unidentified Trematomus spp. and channichthyids were also recorded. Size and wet weight of P. antarcticum were calculated from uneroded otoliths, found in 6 seal stomachs with liquid food pulp, collected during early morning hours in 1985. Size distribution of P. antarcticum from individual seals was reasonably constant, ranging between 5.0 and 22.0 cm SL; adult fish from about 14.0 to 19.0 cm SL predominated. P. antarcticum in seals from the southern area had a larger median size (16.5 cm SL), than those from further east (15.5 cm SL). Calculated wet weights of all P. antarcticum from individual seal stomachs ranged between 4.7 and 16.9 kg the mean was 12.8 kg. Comparisons with net-hauls from the southern Gould Bay suggest that Weddell seals feed mainly in deeper water layers (>400 m) where adult P. antarcticum occur at higher densities.     

The occurrence of Corynosoma strumosum in the grey seal,Halichoerus grypus,caught off the Atlantic coast of Ireland

The occurrence, location and sex ratio of Corynosoma strumosum (Acanthoceophala: Polymorphidae) from 26 juvenile grey seals, Halichoerus grypus, by-caught from around the Inishkea Islands, Co. Mayo, from March to June 1997 were recorded. The location of C. strumosum within the seal did not vary, with all worms being found in the small intestine. The prevalence of infection was 100%, with no other acanthocephalan species being recorded. The mean abundance was 416 (range 80-846) C. strumosum per seal. There was no significant change in abundance by month. The sex ratio of mature female to mature male parasites was 1.2:1. The lengths of female and male worms did not differ significantly.     

EFFECTS OF RESEARCH HANDLING ON THE ENDANGERED HAWAIIAN MONK SEAL

We examined the effects of research handling on free-ranging endangered Hawaiian monk seals, Monachus schauinslandi , by analyzing differences in subsequent year survival, migration, and condition between handled seals and controls during 1983–1998. Each of 549 handled seals was matched to a control seal of the same age, sex, location, and year. Handling included instrumentation with tel metry devices ( n = 93), blood sampling ( n = 19), and tagging ( n = 437). No significant differences were found between handled seals and their controls in one-year resighting rates, observed migration rates, or condition. Resighting rates of handled and control seals were high (80%-100%). Available sample sizes were sufficient to detect reasonably small (9%-20%) differences in resighting rates had they existed among instrumented or tagged seals and controls (α= 0.05, power = 0.90). Too few seals were captured for blood sampling to detect even large differences in their resighting rates. However, blood samples were drawn from most instrumented seals, and there was no indication that this larger group suffered harmful effects. Duration of restraint during flipper tagging had no effect on subsequent probability of resighting. Our analysis suggests that conservative selection procedures and careful handling techniques have no deleterious effects on Hawaiian monk seals.     

Movements of adult female Weddell seals during the winter months

The focus of this study was the distribution of adult female Weddell seals during winter at the Vestfold Hills. Satellite tracking of Weddell seals had never been done before at this location. Hence, this was a pilot study to evaluate the following methods. We attached satellite transmitters to the lower back, where there was least potential to change the seals’ behaviour or to damage instruments on the ice. Location data were obtained only where the seals hauled out, not necessarily where they were feeding. All locations were within the area of fast-ice that was associated with the Vestfold Hills. There were gaps of up to 30 days in the location data sets. Each instrument (n=3) remained attached and functioning for ca. 6 months. During that time, two of the three seals hauled out within small areas adjacent to, or nearby, open water. The same seals hauled out sporadically. We inferred that these seals foraged offshore whilst returning to fast-ice to rest. If Weddell seals forage beneath dynamic ice but return to stable ice as their preferred resting substrate, then evidence of haulout sites will always be a biased measure of foraging range. Tracking seals in the water may be possible using alternative placement of transmitters. However, there is potential for instruments to interfere with movement (breathing and prey capture). For this reason, we recommend a combination of sensors, diet and tracking haulout sites to research winter foraging.     

Effect of methylcobalamin on methotrexate transport in normal and tumorous tissues

The effect of methylcobalamin on 3H-methotrexate uptake by tumor and normal tissues of mice with mammary adenocarcinoma (Ca-755) was studied. Methylcobalamin stimulated the rate of 3H-methotrexate influx into the tumor and small intestine but did not change its influx into the spleen. The effect was dependent on the dose of methylcobalamin. Comparative analysis of the kinetic differences in 3H-methotrexate influx and efflux in tumor and susceptible host tissues revealed the optimal dose of methylcobalamin 0.01 mg/kg to improve the antitumor drug action.     

EFFECTS OF AN OFFSHORE OIL DEVELOPMENT ON LOCAL ABUNDANCE AND DISTRIBUTION OF RINGED SEALS (PHOCA HISPIDA) OF THE ALASKAN BEAUFORT SEA1

This study investigates how densities of ringed seals were affected by construction and oil production activities at Northstar, an artificial island built in the nearshore Alaskan Beaufort Sea. Intensive and replicated aerial surveys of seals on landfast ice were conducted during six spring seasons: for three seasons before island construction began (1997–1999); after a winter of intensive island construction (2000); and after more limited construction plus drilling (2001) and drilling plus oil production (2002). A Poisson regression model was used to examine seal densities relative to distance from Northstar after allowance for environmental covariates. Post hoc power analysis indicated that the study design and Poisson regression approach had high power to detect small‐scale changes in seal densities near Northstar if such changes had occurred. However, seal densities during spring were not significantly affected by proximity to Northstar in 2000–2002. Habitat, temporal, and weather factors did have significant effects on seal densities. This study shows that effects of the Northstar oil development on local distribution of basking ringed seals are no more than slight, and are small relative to the effects of natural environmental factors. An understanding of environmental effects is essential when assessing potential impacts of industrial activity on ringed seals.     

Purification of a new intestinal anti-proliferative factor from normal human small intestine.

Previous studies suggest that intestinal cell proliferation may be controlled by endogenous mitosis inhibitors. We describe here the isolation of a protein named intestinal anti-proliferative factor (IAF) from human small intestine. Successive DEAE anion exchange, isoelectric focusing and gel filtration chromatographies led to a purified anti-proliferative protein fraction used to produce antibodies. Using these antibodies as affinity chromatography ligand, IAF was purified from human small intestine cytosolic fraction. IAF was a potent inhibitor of adenocarcinoma colon cells (HT-29 D4 line) DNA synthesis and proliferation with 50% inhibition observed at picomolar concentrations. Analyzed on SDS/PAGE under reducing conditions, this protein migrates with an apparent molecular mass of 120 kDa and amino acid sequence of two internal peptides displays no homology with another listed protein. Cell cycle studies showed that the growth inhibitory effect was maximal between mid G1 and early S phases. Moreover, flow cytometry studies demonstrated that IAF inhibited the progression of HT-29 D4 cells from G1 to S phase. Northern blot analysis using a dipeptidyl peptidase i.v. probe revealed that the growth arrest mediated by IAF was not linked to differentiation processes. By Western blotting with polyclonal antibodies against IAF, we found that this protein was not detected in differentiated colonic carcinoma. Our results suggest that IAF might regulate intestinal cell proliferation.