Hot and sour: parasite adaptations to honeybee body temperature and pH

Host temperature and gut chemistry can shape resistance to parasite infection. Heat and acidity can limit trypanosomatid infection in warm-blooded hosts and could shape infection resistance in insects as well. The colony-level endothermy and acidic guts of social bees provide unique opportunities to study how temperature and acidity shape insect–parasite associations. We compared temperature and pH tolerance between three trypanosomatid parasites from social bees and a related trypanosomatid from poikilothermic mosquitoes, which have alkaline guts. Relative to the mosquito parasites, all three bee parasites had higher heat tolerance that reflected body temperatures of hosts. Heat tolerance of the honeybee parasite Crithidia mellificae was exceptional for its genus, implicating honeybee endothermy as a plausible filter of parasite establishment. The lesser heat tolerance of the emerging Lotmaria passim suggests possible spillover from a less endothermic host. Whereas both honeybee parasites tolerated the acidic pH found in bee intestines, mosquito parasites tolerated the alkaline conditions found in mosquito midguts, suggesting that both gut pH and temperature could structure host–parasite specificity. Elucidating how host temperature and gut pH affect infection—and corresponding parasite adaptations to these factors—could help explain trypanosomatids' distribution among insects and invasion of mammals.

Hot and sour: parasite adaptations to honey bee body temperature and pH

Host temperature and gut chemistry can shape resistance to parasite infection. Heat and acidity can limit trypanosomatid infection in warm-blooded hosts, and could shape infection resistance in insects as well. The colony-level endothermy and acidic guts of social bees provide unique opportunities to study how temperature and acidity shape insect-parasite associations. We compared temperature and pH tolerance between three trypanosomatid parasites from social bees and a related trypanosomatid from poikilothermic mosquitoes, which have alkaline guts. Relative to the mosquito parasites, all three bee parasites had higher heat tolerance that reflected levels of endothermy in hosts. Heat tolerance of the honey bee parasite Crithidia mellificae was exceptional for its genus, implicating honey bee endothermy as a filter of parasite establishment. The lesser heat tolerance of the emerging Lotmaria passim suggests possible spillover from a less endothermic host. Whereas both honey bee parasites tolerated the acidic pH's found in bee intestines, mosquito parasites tolerated the alkaline conditions found in mosquito midguts, suggesting that both gut pH and temperature could structure host-parasite specificity. Elucidating how host temperature and gut pH affect infection—and corresponding parasite adaptations to these factors—could help explain trypanosomatids' distribution among insects and invasion of mammals. Keywords : thermal performance curve, metabolic theory of ecology, infectious disease ecology, thermoregulation, Apis mellifera, Leishmania

Use of feed additives in animal agriculture: gut response in broilers

Feed additives such as enzymes, probiotics, prebiotics and acidifiers are few examples of suitable alternatives to in – feed antibiotics in animal agriculture due to the ban of antibiotic use. However, the Nigerian poultry industry still experiences cases of antibiotic use. The gut benefits of alternatives to antibiotics often culminate in improved growth performance but there are or may be certain gut responses that attribute to the observed performance of poultry birds. In order to ascertain this, an experiment was conducted to evaluate the effect of antibiotic administration and enzyme supplementation on gut pH and bacteria counts. One hundred and fifty day-old broiler chicks were randomly distributed to three dietary treatments having five replicates and 10 birds per replicate. The experiment lasted forty – two (42) days and was arranged as a completely randomized design. A maize- soybean meal diet not supplemented with antibiotic or enzyme served as the control. Birds fed diet II had antibiotic (Dicoxin plus ®) administered to them. Birds fed diet III had their diets supplemented with enzyme (Roxazyme G2G®). Results indicated pH of the crop to be significantly (P<0.01) reduced by feed additive. The pH of the Ileum was least (5.65) under antibiotic administration but was not significantly different (p>0.05) different that of birds fed control and enzyme supplemented diet. Gizzard pH was acidic but not significantly (P>0.05) across all the treatments. Lactobacillus and Coliform counts were significant (P<0.05) affected by feed additive addition. It can be concluded that feed additive impact on gut pH can influence the type and population of bacteria present in the gastrointestinal tract.

Blood Digestion by Trypsin-Like Serine Protease in the Lyme Disease Vector Tick, Ixodes Scapularis

Ixodes scapularis is the major vector of Lyme disease in the eastern United States. This species undergoes a life cycle consisting of eggs and three active stages: larva, nymph, and adult. Each active life stage takes a blood meal either for developing and molting to the next stage (larvae and nymphs) or for oviposition (adult females). This protein rich blood meal is the only food taken by Ixodes ticks. Most studies on blood digestion in ticks have shown that the initial stages of blood digestion are carried out by cathepsin proteases within endosomes of acidic digestive cells. However, in other hematophagous arthropods, the serine protease trypsin plays an important role in early protein degradation. In this study, we determined transcript expression of I. scapularis cathepsins and serine proteases, some with previously characterized roles in blood digestion. Gut pH was also determined and a trypsin-benzoyl-D, L-arginine 4-nitoanilide assay was used to measure active trypsin levels during blood digestion. Our data suggest that trypsin levels increase significantly after blood feeding and peaked in larvae, nymphs, and adults at 3, 1, and 1 days post host detachment, respectively. In addition, alkaline gut pH (8.0) conditions after I. scapularis blood feeding were similar to those required for trypsin activity in other arthropods suggesting these enzymes have an important and previously overlooked role in I. scapularis blood digestion.

Microbiota supplementation with Bifidobacterium and Lactobacillus modifies the preterm infant gut microbiota and metabolome

Supplementation with members of the early-life microbiota or ‘probiotics’ is becoming increasingly popular to attempt to beneficially manipulate the preterm gut microbiota. We performed a large longitudinal study comprising two preterm groups; 101 orally supplemented with Bifidobacterium and Lactobacillus (Bif/Lacto) and 133 non-supplemented (Control) matched by age, sex, birth-mode, and diet. 16S rRNA metataxonomic profiling on stool samples (n = 592) indicated a predominance of Bifidobacterium, and a reduction of pathobionts in the Bif/Lacto group. Metabolic phenotyping found a parallel increase in fecal acetate and lactate in the Bif/Lacto group compared to the Control group, which positively correlated with Bifidobacterium abundance consistent with the ability of the supplemented Bifidobacterium strain to metabolize human milk oligosaccharides and reduced gut pH. This study demonstrates that microbiota supplementation can modify the preterm microbiome and the gastrointestinal environment to more closely resemble that of a full-term infant.