Diet and phylogeny shape the gut microbiota of Antarctic seals: a comparison of wild and captive animals

The gut microbiota of mammals underpins the metabolic capacity and health of the host. Our understanding of what influences the composition of this community has been limited primarily to evidence from captive and terrestrial mammals. Therefore, the gut microbiota of southern elephant seals, Mirounga leonina, and leopard seals, Hydrurga leptonyx, inhabiting Antarctica were compared with captive leopard seals. Each seal exhibited a gut microbiota dominated by four phyla: Firmicutes (41.5 ± 4.0%), Fusobacteria (25.6 ± 3.9%), Proteobacteria (17.0 ± 3.2%) and Bacteroidetes (14.1 ± 1.7%). Species, age, sex and captivity were strong drivers of the composition of the gut microbiota, which can be attributed to differences in diet, gut length and physiology and social interactions. Differences in particular prey items consumed by seal species could contribute to the observed differences in the gut microbiota. The longer gut of the southern elephant seal provides a habitat reduced in available oxygen and more suitable to members of the phyla Bacteroidetes compared with other hosts. Among wild seals, 16 ‘core’ bacterial community members were present in the gut of at least 50% of individuals. As identified between southern elephant seal mother–pup pairs, ‘core’ members are passed on via vertical transmission from a young age and persist through to adulthood. Our study suggests that these hosts have co‐evolved with their gut microbiota and core members may provide some benefit to the host, such as developing the immune system. Further evidence of their strong evolutionary history is provided with the presence of 18 shared ‘core’ members in the gut microbiota of related seals living in the Arctic. The influence of diet and other factors, particularly in captivity, influences the composition of the community considerably. This study suggests that the gut microbiota has co‐evolved with wild mammals as is evident in the shared presence of ‘core’ members.     

The shape and dynamics of the Leptospiraceae

Most swimming bacteria produce thrust by rotating helical filaments called flagella. Typically, the flagella stick out into the external fluid environment; however, in the spirochetes, a unique group that includes some highly pathogenic species of bacteria, the flagella are internalized, being incased in the periplasmic space; i.e., between the outer membrane and the cell wall. This coupling between the periplasmic flagella and the cell wall allows the flagella to serve a skeletal, as well as a motile, function. In this article, we propose a mathematical model for spirochete morphology based on the elastic interaction between the cell body and the periplasmic flagella. This model describes the mechanics of the composite structure of the cell cylinder and periplasmic flagella and accounts for the morphology of Leptospiraceae. This model predicts that the cell cylinder should be roughly seven times stiffer than the flagellum. In addition, we explore how rotation of the periplasmic flagellum deforms the cell cylinder during motility. We show that the transition between hook-shaped and spiral-shaped ends is purely a consequence of the change in direction of the flagellar motor and does not require flagellar polymorphism.     

The emerging shape of the ESCRT machinery

The past two years have seen an explosion in the structural understanding of the endosomal sorting complex required for transport (ESCRT) machinery that facilitates the trafficking of ubiquitylated proteins from endosomes to lysosomes via multivesicular bodies (MVBs). A common organization of all ESCRTs is a rigid core attached to flexibly connected modules that recognize other components of the MVB pathway. Several previously unsuspected key links between multiple ESCRT subunits, phospholipids and ubiquitin have now been elucidated, which, together with the detailed morphological analyses of ESCRT-depletion phenotypes, provide new insights into the mechanism of MVB biogenesis.     

High density electromyography data of normally limbed and transradial amputee subjects for multifunction prosthetic control

Pattern recognition based control of powered upper limb myoelectric prostheses offers a means of extracting more information from the available muscles than conventional methods. By identifying repeatable patterns of muscle activity across multiple muscle sites rather than relying on independent EMG signals it is possible to provide more natural, reliable control of myoelectric prostheses. The purposes of this study were to (1) determine if participants can perform distinctive muscle activation patterns associated with multiple wrist and hand movements reliably and (2) to show that high density EMG can be applied individually to determine the electrode location of a clinically acceptable number of electrodes (maximally eight) to classify multiple wrist and hand movements reliably in transradial amputees. Eight normally limbed subjects (five female, three male) and four transradial amputee subjects (two traumatic and congenital) subjects participated in this study, which examined the classification accuracies of a pattern recognition control system. It was found that tasks could be classified with high accuracy (85-98%) with normally limbed subjects (10-13 tasks) and with amputees (4-6) tasks. In healthy subjects, reducing the number of electrodes to eight did not affect accuracy significantly when those electrodes were optimally placed, but did reduce accuracy significantly when those electrodes were distributed evenly. In the amputee subjects, reducing the number of electrodes up to 4 did not affect classification accuracy or the number of tasks with high accuracy, independent of whether those remaining electrodes were evenly distributed or optimally placed. The findings in healthy subjects suggest that high density EMG testing is a useful tool to identify optimal electrode sites for pattern recognition control, but its use in amputees still has to be proven. Instead of just identifying the electrode sites where EMG activity is strong, clinicians will be able to choose the electrode sites that provide the most important information for classification.     

The role of animals in the epidemiology of the mycoses

The role that animals play in the epidemiology of human mycoses is discussed here. It can be divided as follows:Animals as vectors of mycoses — This role is especially important as far as dermatophytozoonoses are concerned, these being of both the urban type, mainly due to Microsporum canis, and of the rural type, mainly due to Trichophyton verrucosum. These dermatophytozoonoses are emerging problems in present, modern pathology, especially in urban areas. These conditions may also be responsible for important occupational diseases for livestock, rabbit and laboratory attendants. Both domestic animals and wildlife are often asymptomatic carriers.Animal substrates as growths factor for pathogenic fungi — The fact that bird or bat feces may contain factors that favour the growth of some fungous organisms in the environment has long been recognized. It is established fact that soil animalization (i.e., the addition of such debris as hair, skin scales, droppings and other organic matters) create an environmental medium suitable for the growth of geophilic fungi such as Histoplasma capsulatum, Cryptococcus neoformans and M. gypseum.Possible role of animals in the recycling of fungi from foodstuffs and environment — The possible role of animals in determining human pathology has become an emerging problem for which new data are accumulating both on pathogenic fungi and mycotoxins.The use of animals in monitoring mycoses — Animals may reveal the presence of a pathogen in a given area. This phenomenon has been exploited to monitor the natural occurrence of various mycoses (e.g., coccidioidomycosis, histoplasmosis, dermatomycoses) in different regions. The use of sentinel animals (i.e., the introduction of susceptible animals in certain environments to detect the presence of a pathogen) has not been duly exploited.     

The gastric mucus of domestic animals

The gastric mucus of different domestic mammals shows a certain pattern of reactions which is typical for the species but not for the respective gland. There is no "mucoid" as an uniform specific mucus substance and a greater plurality in the composition of the secretions as it is reflected by the classification in acid and neutral mucins. A classification of the glands as to the secretion is problematical and further consideration is necessary.     

The collagen content of selected animals

The collagen contents of a selected group of animals have been determined and considered in relation to a hypothesis that animals which changed from phosphoarginine to other phosphagens had a selective advantage in converting arginine to proline for the synthesis of connective tissue.