Changes in the composition and physiological and biochemical properties of fungi during passage through the digestive tract of earthworms

It was established that the biomass of fungal mycelium decreased by 30–50% during passage through the intestine of the Aporrectodea caliginosa and Lumbricus terrestris earthworms, while its content in empty intestines was 40–60% less than in the soil. It was found that the amount of mycelium increases again in three-day-old coprolites due to the rapid growth of the species. It was demonstrated that the physiological activity of fungi (estimated according to the time of the appearance of colonies on the medium and probability of propagation) is lower in the intestine content, digestive tract, and fresh excrement of the worms than in the soil. It was noted that the activity and diversity of organic substrates (utilized by fungi), as well as proteolytic activity is lower in fungal isolates from the intestine than from the soil. It was registered that the death of a part of the fungi occurs in the worm intestine, while the physiological state changes in the animals withstanding the effect of the digestive medium.     

The yeast spore wall enables spores to survive passage through the digestive tract of Drosophila

In nature, yeasts are subject to predation by flies of the genus Drosophila. In response to nutritional starvation Saccharomyces cerevisiae differentiates into a dormant cell type, termed a spore, which is resistant to many types of environmental stress. The stress resistance of the spore is due primarily to a spore wall that is more elaborate than the vegetative cell wall. We report here that S. cerevisiae spores survive passage through the gut of Drosophila melanogaster. Constituents of the spore wall that distinguish it from the vegetative cell wall are necessary for this resistance. Ascospores of the distantly related yeast Schizosaccharomyces pombe also display resistance to digestion by D. melanogaster. These results suggest that the primary function of the yeast ascospore is as a cell type specialized for dispersion by insect vectors.     

Influence of the load of nylon capsules on their passage through the digestive tract and specific gravity

The passage and specific gravity of nylon capsules were evaluated in five trials. In individual trials, different lactating cows were fed the same diet consisting of maize silage, alfalfa hay and concentrate. In each trial the different feeds (or no feed) were used to fill the capsules. The capsules were made of nylon cloth (42 microm pore size, 10 mm external diameter). The different weights of the load (L1-L5) were obtained using a combination of 2 and 3 mm stainless steel balls. The highest recovery of the capsules was obtained with the L3 and L4 loads (91.4 and 92.3%, resp.). After 14 hours of incubation in the rumen, the calculated values of functional specific gravity of the capsules ranged from 0.92 to 2.05 g x cm(-3). It was concluded that L3 (one 2 mm and one 3 mm ball) was the suitable weight of the load.     

Loss of graft-versus-host reactivity of mouse lymphocytes during serial passage through irradiated allogeneic hosts

Lymphoid cells which are injected into heavily x-irradiated allogeneic mice proliferate in the recipient spleens and exhibit immunological reactivity against cells of recipient genotype. We have tested whether the immunological reactivity of such cells can be further increased by injections into irradiated secondary and tertiary hosts of the same genotype. Cellular immunity of the cells was measured in a graft-vs-host test which is based on the principle that lymphocytes can inhibit the proliferation of allogeneic bone marrow cells in the spleens of irradiated recipients.Cells obtained from lymph nodes or thymi exhibited an increased graft-vs-host reactivity after five days' residence in the spleens of irradiated allogeneic mice. Attempts to sensitize these cells further by injection into secondary and tertiary irradiated recipients of the same genotype resulted in a progressive loss of their graft-vs-host reactivity. Cell counts in the spleens indicated that the proliferative activity was highest for nonsensitized and lowest for sensitized cell populations, indicating that the decline in immunological activity may be due to a decreased proliferative activity of the cells as a result of the response to the specific antigens.     

Snails can survive passage through a bird’s digestive system

Aim Predation is generally viewed as a factor that limits the distribution of animal prey species. However, in certain instances, such as seed dispersal, predation may enhance the dispersal capability of prey species. In a prior study, we found that land snails are preyed upon by the Japanese white‐eye (Zosterops japonicus) and the brown‐eared bulbul (Hypsipetes amaurotis) in the Ogasawara Islands. In this paper we provide experimental and field evidence indicating that land snails could potentially be dispersed through bird predation. Location Hahajima Island of the Ogasawara Islands in the western Pacific. Methods Experimentation was first performed to test whether the land snail Tornatellides boeningi could remain alive after being swallowed and passed through the bird digestive system. Next, in order to investigate the potential role of internal bird transport and dispersal of this snail, we investigated the relationship between the distribution of population genetic diversity in the snail and the regional geographical abundance of predatory birds. The population genetic structure of T. boeningi and isolation by distance were inferred with Arlequin . The association between nucleotide diversity in T. boeningi populations and population density of predators was examined using a generalized linear mixed model. We conducted a likelihood ratio test for the full model and for another model that removed the fixed effect. Results Of the 119 snails fed to Japanese white‐eyes and 55 snails fed to brown‐eared bulbuls, 14.3% and 16.4% of the snails, respectively, passed through the gut alive. Additionally, one snail gave birth to juveniles after emerging from a bird’s gut. Significant heterogeneity among the populations of T. boeningi on Hahajima was indicated using AMOVA; however, there was no evidence of isolation by distance. A positive correlation was found between levels of mitochondrial DNA variation among and within T. boeningi populations and the density of Japanese white‐eyes in the wild. Main conclusions Bird predation appears to be a method of dispersal for T. boeningi, and our results suggest that bird‐mediated dispersal plays a role in land snail population structure.     

Duroquinone reduction during passage through the pulmonary circulation

The lungs can substantially influence the redox status of redox-active plasma constituents. Our objective was to examine aspects of the kinetics and mechanisms that determine pulmonary disposition of redox-active compounds during passage through the pulmonary circulation. Experiments were carried out on rat and mouse lungs with 2,3,5,6-tetramethyl-1,4-benzoquinone [duroquinone (DQ)] as a model amphipathic quinone reductase substrate. We measured DQ and durohydroquinone (DQH2) concentrations in the lung venous effluent after injecting, or while infusing, DQ or DQH2 into the pulmonary arterial inflow. The maximum net rates of DQ reduction to DQH2 in the rat and mouse lungs were approximately 4.9 and 2.5 micromol. min(-1).g dry lung wt(-1), respectively. The net rate was apparently the result of freely permeating access of DQ and DQH2 to tissue sites of redox reactions, dominated by dicumarol-sensitive DQ reduction to DQH2 and cyanide-sensitive DQH2 reoxidation back to DQ. The dicumarol sensitivity along with immunodetectable expression of NAD(P)H-quinone oxidoreductase 1 (NQO1) in the rat lung tissue suggest cytoplasmic NQO1 as the dominant site of DQ reduction. The effect of cyanide on DQH2 oxidation suggests that the dominant site of oxidation is complex III of the mitochondrial electron transport chain. If one envisions DQ as a model compound for examining the disposition of amphipathic NQO1 substrates in the lungs, the results are consistent with a role for lung NQO1 in determining the redox status of such compounds in the circulation. For DQ, the effect is conversion of a redox-cycling, oxygen-activating quinone into a stable hydroquinone.     

Maturational changes in the survivability and fertility of fowl sperm during their passage through the male reproductive tract

The objective of this study was to examine whether domestic fowl (Gallus domesticus) sperm undergo maturation in their capacity for survival and fertilization in the male reproductive tract. Sperm collected from the testis, epididymis and the proximal, middle and distal vas deferens were simultaneously stored in vitro in minimum essential medium (MEM) at 39°C for 0, 3 and 6h, and at 4°C for 24 and 48h. Sperm membrane integrity was measured using the dual fluorescent stain SYBR-14/propidium iodide (PI). Aliquots of sperm from the various sites were subjected to artificial insemination (AI) into the uteri of hens to assess the duration of sperm survival in the oviduct and to determine the fertility status of the sperm. Testicular sperm exhibited a very low capacity to survive under in vitro liquid storage conditions, irrespective of the storage temperature used, and in the oviduct, and they had a low ability to fertilize the ovum. On the contrary, sperm from the distal vas deferens had a higher survival rate during in vitro storage periods, a longer life span in the oviduct, and high fertility. Survival and fertilizing capacity of the sperm recovered from the testes increased gradually (P<0.05) from the testes to the distal vas deferens. In conclusion, we suggest that fowl sperm may undergo functional maturation through a process of gradual changes in their survival and fertilization capacities during their passage through the successive parts of the male reproductive tract.     

Survival of Lactobacillus casei in the human digestive tract after consumption of fermented milk

A human trial was carried out to assess the ileal and fecal survival of Lactobacillus casei DN-114 001 ingested in fermented milk. Survival rates were up to 51.2% in the ileum and 28.4% in the feces. The probiotic bacterium has the capacity to survive during its transit through the human gut.     

Survival, physiology, and lysis of Lactococcus lactis in the digestive tract.

The survival and the physiology of lactococcal cells in the different compartments of the digestive tracts of rats were studied in order to know better the fate of ingested lactic acid bacteria after oral administration. For this purpose, we used strains marked with reporter genes, the luxA-luxB gene of Vibrio harveyi and the gfp gene of Aequora victoria, that allowed us to differentiate the inoculated bacteria from food and the other intestinal bacteria. Luciferase was chosen to measure the metabolic activity of Lactococcus lactis in the digestive tract because it requires NADH, which is available only in metabolically active cells. The green fluorescent protein was used to assess the bacterial lysis independently of death. We report not only that specific factors affect the cell viability and integrity in some digestive tract compartments but also that the way bacteria are administrated has a dramatic impact. Lactococci which transit with the diet are quite resistant to gastric acidity (90 to 98% survival). In contrast, only 10 to 30% of bacteria survive in the duodenum. Viable cells are metabolically active in each compartment of the digestive tract, whereas most dead cells appear to be subject to rapid lysis. This property suggests that lactococci could be used as a vector to deliver specifically into the duodenum the proteins produced in the cytoplasm. This type of delivery vector would be particularly appropriate for targeting digestive enzymes such as lipase to treat pancreatic deficiencies.     

Functional properties of free and encapsulated Lactobacillus reuteri DPC16 during and after passage through a simulated gastrointestinal tract

Lactobacillus reuteri DPC16 is a probiotic bacterium that has strong antimicrobial activities on pathogens, mainly due to its ability to produce reuterin, an antimicrobial compound. The objective of this study was to examine the ability of an encapsulation technique to protect the functional properties of cells of L. reuteri DPC16 during passage through a simulated GI tract. The functional properties of the cells were studied before and after passage through the tract. An alginate-skim milk encapsulation system was used to deliver the probiotic bacterium through the simulated GI tract, allowing for the release of the cells into the simulated colonic fluid. The cells were then isolated and cultured. The recovered cells showed no diminution in functional properties, including their growth kinetics, ability to adhere to epithelial cells and ability to inhibit the adhesion of E. coli to epithelial cells. The bacteriostatic and bactericidal properties of the recovered cells against some pathogens were significantly greater (P < 0.05) than those of the original cells. Production of reuterin by the recovered cells was significantly greater than that of the original cells when cultured in MRS medium in the absence of its metabolic precursor, glycerol. The results demonstrate significant consequences for the application of the encapsulation technique to protect and/or enhance the functional properties of the probiotic cells.