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Veterinary Research 2009Leishmania spp. are polarized single-celled eukaryotic parasites, the perpetuation of which relies on two other organisms they "use" as hosts. One of the Leishmania host... (Review)
Review
Leishmania spp. are polarized single-celled eukaryotic parasites, the perpetuation of which relies on two other organisms they "use" as hosts. One of the Leishmania host organisms is a blood-feeding female sand fly, the second host being a mammal that acts as a blood source for the female sand fly. Leishmania-hosting sand flies transmit the metacyclic promastigote developmental stage to the mammal skin. While many mammals are known to act as sand fly blood sources, only some of these mammals are/ will be "used" as Leishmania hosts. This host status means that skin as well as skin-distant tissues and cell lineages (mononuclear phagocytes and fibroblasts) of these mammals are rapidly and continuously remodelled as niches where Leishmania will deploy its developmental programs: it is noteworthy that without the deployment of the developmental program underlying Leishmania transmission from the mammal to the blood-searching and blood-feeding sand flies, the perpetuation of Leishmania will be suspended. While post genomic approaches are providing insight about some features of Leishmania major, Leishmania infantum/chagasi and Leishmania braziliensis, such approaches are not yet available for the natural hosts (wild rodents, wild sand flies) these Leishmania species "use" as hosts.
Topics: Animals; Female; Host-Parasite Interactions; Humans; Leishmania; Mammals; Psychodidae
PubMed: 19379663
DOI: 10.1051/vetres/2009021 -
Current Biology : CB Jul 2021Mammal evolution in the Mesozoic was thought to be heavily constrained by competition and predation by dinosaurs. A new study suggests that placental mammals remained...
Mammal evolution in the Mesozoic was thought to be heavily constrained by competition and predation by dinosaurs. A new study suggests that placental mammals remained constrained for several million years after non-avian dinosaurs perished, perhaps due to competition from archaic mammals.
Topics: Animals; Biological Evolution; Dinosaurs; Female; Fossils; Mammals; Placenta; Pregnancy
PubMed: 34256913
DOI: 10.1016/j.cub.2021.05.003 -
Proceedings of the National Academy of... Feb 2017Genome size in mammals and birds shows remarkably little interspecific variation compared with other taxa. However, genome sequencing has revealed that many mammal and...
Genome size in mammals and birds shows remarkably little interspecific variation compared with other taxa. However, genome sequencing has revealed that many mammal and bird lineages have experienced differential rates of transposable element (TE) accumulation, which would be predicted to cause substantial variation in genome size between species. Thus, we hypothesize that there has been covariation between the amount of DNA gained by transposition and lost by deletion during mammal and avian evolution, resulting in genome size equilibrium. To test this model, we develop computational methods to quantify the amount of DNA gained by TE expansion and lost by deletion over the last 100 My in the lineages of 10 species of eutherian mammals and 24 species of birds. The results reveal extensive variation in the amount of DNA gained via lineage-specific transposition, but that DNA loss counteracted this expansion to various extents across lineages. Our analysis of the rate and size spectrum of deletion events implies that DNA removal in both mammals and birds has proceeded mostly through large segmental deletions (>10 kb). These findings support a unified "accordion" model of genome size evolution in eukaryotes whereby DNA loss counteracting TE expansion is a major determinant of genome size. Furthermore, we propose that extensive DNA loss, and not necessarily a dearth of TE activity, has been the primary force maintaining the greater genomic compaction of flying birds and bats relative to their flightless relatives.
Topics: Animals; Birds; DNA; DNA Transposable Elements; Evolution, Molecular; Genome; Genome Size; Genomics; Mammals; Phylogeny
PubMed: 28179571
DOI: 10.1073/pnas.1616702114 -
Biochemistry. Biokhimiia Dec 2017Programmed (adaptive) aging refers to the idea that mammals, including humans and other complex organisms, have evolved mechanisms that purposely cause or allow... (Review)
Review
Programmed (adaptive) aging refers to the idea that mammals, including humans and other complex organisms, have evolved mechanisms that purposely cause or allow senescence or otherwise internally limit their lifespans in order to obtain an evolutionary advantage. Until recently, programmed aging had been thought to be theoretically impossible because of the mechanics of the evolution process. However, there is now substantial theoretical and empirical support for the existence of programmed aging in mammals. Therefore, a comprehensive approach to medical research on aging and age-related diseases must consider programmed aging mechanisms and the detailed nature of such mechanisms is of major importance. Theories of externally regulated programmed aging suggest that in mammals and other complex organisms, genetically specified senescence mechanisms detect local or temporary external conditions that affect the optimal lifespan for a species population and can adjust the lifespans of individual members in response. This article describes why lifespan regulation in response to external conditions adds to the evolutionary advantage produced by programmed aging and why a specific externally regulated programmed aging mechanism provides the best match to empirical evidence on mammal senescence.
Topics: Aging; Animals; Biological Clocks; Biological Evolution; Humans; Longevity; Mammals; Reproduction; Stress, Physiological
PubMed: 29486694
DOI: 10.1134/S0006297917120033 -
PloS One 2013Marine mammals have greatly benefitted from a shift from resource exploitation towards conservation. Often lauded as symbols of conservation success, some marine mammal...
Marine mammals have greatly benefitted from a shift from resource exploitation towards conservation. Often lauded as symbols of conservation success, some marine mammal populations have shown remarkable recoveries after severe depletions. Others have remained at low abundance levels, continued to decline, or become extinct or extirpated. Here we provide a quantitative assessment of (1) publicly available population-level abundance data for marine mammals worldwide, (2) abundance trends and recovery status, and (3) historic population decline and recent recovery. We compiled 182 population abundance time series for 47 species and identified major data gaps. In order to compare across the largest possible set of time series with varying data quality, quantity and frequency, we considered an increase in population abundance as evidence of recovery. Using robust log-linear regression over three generations, we were able to classify abundance trends for 92 spatially non-overlapping populations as Significantly Increasing (42%), Significantly Decreasing (10%), Non-Significant Change (28%) and Unknown (20%). Our results were comparable to IUCN classifications for equivalent species. Among different groupings, pinnipeds and other marine mammals (sirenians, polar bears and otters) showed the highest proportion of recovering populations, likely benefiting from relatively fast life histories and nearshore habitats that provided visibility and protective management measures. Recovery was less frequent among cetaceans, but more common in coastal than offshore populations. For marine mammals with available historical abundance estimates (n = 47), larger historical population declines were associated with low or variable recent recoveries so far. Overall, our results show that many formerly depleted marine mammal populations are recovering. However, data-deficient populations and those with decreasing and non-significant trends require attention. In particular, increased study of populations with major data gaps, including offshore small cetaceans, cryptic species, and marine mammals in low latitudes and developing nations, is needed to better understand the status of marine mammal populations worldwide.
Topics: Animals; Conservation of Energy Resources; Mammals; Marine Biology; Population Dynamics
PubMed: 24205025
DOI: 10.1371/journal.pone.0077908 -
Biological Reviews of the Cambridge... Apr 2019Autophagy is primarily an efficient intracellular catabolic pathway used for degradation of abnormal cellular protein aggregates and damaged organelles. Although... (Review)
Review
Autophagy is primarily an efficient intracellular catabolic pathway used for degradation of abnormal cellular protein aggregates and damaged organelles. Although autophagy was initially proposed to be a cellular stress responder, increasing evidence suggests that it carries out normal physiological roles in multiple biological processes. To date, autophagy has been identified in most organs and at many different developmental stages, indicating that it is not only essential for cellular homeostasis and renovation, but is also important for organ development. Herein, we summarize our current understanding of the functions of autophagy (which here refers to macroautophagy) in the mammalian life cycle.
Topics: Animals; Autophagosomes; Autophagy; Life Cycle Stages; Lysosomes; Mammals; Stem Cells
PubMed: 30239126
DOI: 10.1111/brv.12464 -
Parasites & Vectors Jun 2022Ixodid ticks are important vectors for zoonotic pathogens, with Ixodes ricinus being the most important in Europe. Rodents are hosts of immature life stages of I....
BACKGROUND
Ixodid ticks are important vectors for zoonotic pathogens, with Ixodes ricinus being the most important in Europe. Rodents are hosts of immature life stages of I. ricinus ticks and are considered main reservoirs for tick-borne pathogens, e.g. Borrelia burgdorferi. The aim of this study was to analyse the prevalence as well as genospecies and sequence type (ST) diversity of Borrelia burgdorferi sensu lato in ticks and small mammals from central Germany and to elaborate on the influence of environmental and/or individual host and vector factors on Borrelia prevalence.
METHODS
After species identification, 1167 small mammal skin samples and 1094 ticks from vegetation were screened by B. burgdorferi sensu lato real-time polymerase chain reaction, and positive samples were characterized by multilocus sequence typing. Generalized linear (mixed) models were used to estimate how seasonality, small mammal species/tick life stage and habitat affect individual infection status.
RESULTS
In total, 10 small mammal species and three tick species, Ixodes ricinus, Ixodes inopinatus (both considered members of the I. ricinus complex) and Dermacentor reticulatus, were investigated. Borrelia DNA was detected in eight host species, i.e. the striped field mouse (Apodemus agrarius), the yellow-necked field mouse (Apodemus flavicollis), the wood mouse (Apodemus sylvaticus), the water vole (Arvicola amphibius), the bank vole (Clethrionomys glareolus), the field vole (Microtus agrestis), the common vole (Microtus arvalis), and the common shrew (Sorex araneus). Two species were Borrelia negative, the greater white-toothed shrew (Crocidura russula) and the pygmy shrew (Sorex minutus). The average prevalence was 6.2%, with two genospecies detected, Borrelia afzelii and Borrelia garinii, and at least three STs that had not been previously reported in small mammals. Borrelia prevalence in small mammals did not differ between seasons. Six genospecies of Borrelia-Borrelia afzelii, Borrelia valaisiana, Borrelia garinii, Borrelia lusitaniae, Borrelia spielmanii, and Borrelia burgdorferi sensu stricto-and 25 STs of Borrelia, of which 12 have not been previously described at all and five have not been previously reported in Germany, were detected in 13% of I. ricinus complex ticks. Prevalence was highest in adult females (25.3%) and lowest in nymphs (11.4%). Prevalence was significantly higher in ticks from grassland (16.8%) compared to forests (11.4%).
CONCLUSIONS
The high level of small mammal diversity in this region of Germany seems to be reflected in a wide variety of genospecies and STs of B. burgdorferi.
Topics: Animals; Arvicolinae; Borrelia; Borrelia burgdorferi; Borrelia burgdorferi Group; Ecosystem; Female; Ixodes; Lyme Disease; Mice; Murinae; Shrews
PubMed: 35672762
DOI: 10.1186/s13071-022-05326-3 -
The Journal of Veterinary Medical... Jun 2014The olfactory receptor organs and their primary centers are classified into several types. The receptor organs are divided into fish-type olfactory epithelium (OE),...
The olfactory receptor organs and their primary centers are classified into several types. The receptor organs are divided into fish-type olfactory epithelium (OE), mammal-type OE, middle chamber epithelium (MCE), lower chamber epithelium (LCE), recess epithelium, septal olfactory organ of Masera (SO), mammal-type vomeronasal organ (VNO) and snake-type VNO. The fish-type OE is observed in flatfish and lungfish, while the mammal-type OE is observed in amphibians, reptiles, birds and mammals. The MCE and LCE are unique to Xenopus and turtles, respectively. The recess epithelium is unique to lungfish. The SO is observed only in mammals. The mammal-type VNO is widely observed in amphibians, lizards and mammals, while the snake-type VNO is unique to snakes. The VNO itself is absent in turtles and birds. The mammal-type OE, MCE, LCE and recess epithelium seem to be descendants of the fish-type OE that is derived from the putative primitive OE. The VNO may be derived from the recess epithelium or fish-type OE and differentiate into the mammal-type VNO and snake-type VNO. The primary olfactory centers are divided into mammal-type main olfactory bulbs (MOB), fish-type MOB and mammal-type accessory olfactory bulbs (AOB). The mammal-type MOB first appears in amphibians and succeeds to reptiles, birds and mammals. The fish-type MOB, which is unique to fish, may be the ancestor of the mammal-type MOB. The mammal-type AOB is observed in amphibians, lizards, snakes and mammals and may be the remnant of the fish-type MOB.
Topics: Animals; Olfactory Mucosa; Phylogeny; Receptors, Odorant; Species Specificity; Vertebrates; Vomeronasal Organ
PubMed: 24531771
DOI: 10.1292/jvms.13-0650 -
Anatomical Record (Hoboken, N.J. : 2007) Mar 2022The sense of taste is associated with the evaluation of food and other environmental parameters such as salinity. In aquatic mammals, anatomic and behavioral evidence of...
The sense of taste is associated with the evaluation of food and other environmental parameters such as salinity. In aquatic mammals, anatomic and behavioral evidence of the use of taste varies by species and genomic analysis of taste receptors indicates an overall reduction and, in some cases, complete loss of intact bitter and sweet taste receptors. However, the receptors used by taste buds in the oral cavity are found on cells in other areas of the body and play an important role in immune responses. In the respiratory tract, an example of such cells is solitary chemosensory cells (SCCs) which have bitter and sweet taste receptors. The bitter receptors detect chemicals given off by pathogens and initiate an innate immune response. Although many aquatic mammals may not have a role for taste in the assessment of food, they likely would benefit from the added protection that SCCs provide, especially considering respiratory diseases are a problem for many aquatic mammals. While evidence indicates that some species do not possess functional bitter receptors for taste, many do have intact bitter receptor genes and it is important for researchers to be aware of all roles for these receptors in homeostasis. Through a better understanding of the anatomy and physiology of aquatic mammal's respiratory systems, better treatment and management is possible.
Topics: Animals; Immunity, Innate; Mammals; Receptors, G-Protein-Coupled; Taste; Taste Buds
PubMed: 34264538
DOI: 10.1002/ar.24708 -
Conservation Physiology 2023Over the past several decades, scientists have constructed bioenergetic models for marine mammals to assess potential population-level consequences following exposure to...
Over the past several decades, scientists have constructed bioenergetic models for marine mammals to assess potential population-level consequences following exposure to a disturbance, stressor, or environmental change, such as under the Population Consequences of Disturbance (pCOD) framework. The animal's metabolic rate (rate of energy expenditure) is a cornerstone for these models, yet the cryptic lifestyles of marine mammals, particularly cetaceans, have limited our ability to quantify basal (BMR) and field (FMR) metabolic rates using accepted 'gold standard' approaches (indirect calorimeter via oxygen consumption and doubly labeled water, respectively). Thus, alternate methods have been used to quantify marine mammal metabolic rates, such as extrapolating from known allometric relationships (e.g. Kleiber's mouse to elephant curve) and developing predictive relationships between energy expenditure and physiological or behavioral variables. To understand our current knowledge of marine mammal metabolic rates, we conducted a literature review (1900-2023) to quantify the magnitude and variation of metabolic rates across marine mammal groups. A compilation of data from studies using 'gold standard' methods revealed that BMR and FMR of different marine mammal species ranges from 0.2 to 3.6 and 1.1 to 6.1 x Kleiber, respectively. Mean BMR and FMR varied across taxa; for both measures odontocete levels were intermediate to higher values for otariids and lower values of phocids. Moreover, multiple intrinsic (e.g. age, sex, reproduction, molt, individual) and extrinsic (e.g. food availability, water temperature, season) factors, as well as individual behaviors (e.g. animal at water's surface or submerged, activity level, dive effort and at-sea behaviors) impact the magnitude of these rates. This review provides scientists and managers with a range of reliable metabolic rates for several marine mammal groups as well as an understanding of the factors that influence metabolism to improve the discernment for inputs into future bioenergetic models.
PubMed: 37790839
DOI: 10.1093/conphys/coad077