scholarly journals Diversity of MHC IIB genes and parasitism in hybrids of evolutionarily divergent cyprinoid species indicate heterosis advantage

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Andrea Šimková ◽  
Lenka Gettová ◽  
Kristína Civáňová ◽  
Mária Seifertová ◽  
Michal Janáč ◽  
...  
Keyword(s):  
Seasonal Effect ◽  
Parasite Communities ◽  
Histocompatibility Complex ◽  
Interspecies Hybrids ◽  
Allele Expression ◽  
In The Wild ◽  
Species Specific ◽  
Mhc Alleles ◽  
Mhc Iib ◽  
Mhc Supertypes

AbstractThe genes of the major histocompatibility complex (MHC) are an essential component of the vertebrate immune system and MHC genotypes may determine individual susceptibility to parasite infection. In the wild, selection that favors MHC variability can create situations in which interspecies hybrids experience a survival advantage. In a wild system of two naturally hybridizing leuciscid fish, we assessed MHC IIB genetic variability and its potential relationships to hosts’ ectoparasite communities. High proportions of MHC alleles and parasites were species-specific. Strong positive selection at specific MHC codons was detected in both species and hybrids. MHC allele expression in hybrids was slightly biased towards the maternal species. Controlling for a strong seasonal effect on parasite communities, we found no clear associations between host-specific parasites and MHC alleles or MHC supertypes. Hybrids shared more MHC alleles with the more MHC-diverse parental species, but expressed intermediate numbers of MHC alleles and positively selected sites. Hybrids carried significantly fewer ectoparasites than either parent species, suggesting a hybrid advantage via potential heterosis.

scholarly journals Natural Selection on MHC IIb in Parapatric Lake and Stream Stickleback: Balancing, Divergent, Both, or Neither?

2016 ◽  
Author(s):  
William E. Stutz ◽  
Daniel I. Bolnick
Keyword(s):  
Allelic Variation ◽  
Balancing Selection ◽  
Divergent Selection ◽  
Parasite Communities ◽  
Mhc Genes ◽  
Mhc Polymorphism ◽  
Novel Strategy ◽  
Spatially Varying ◽  
Mhc Alleles ◽  
Mhc Iib

AbstractMajor histocompatibility (MHC) genes encode proteins that play a central role in vertebrates’ adaptive immunity to parasites. MHC loci are among the most polymorphic in vertebrates’ genomes, inspiring many studies to identify evolutionary processes driving MHC polymorphism within populations, and divergence between populations. Leading hypotheses include balancing selection favoring rare alleles within populations, and spatially divergent selection. These hypotheses do not always produce diagnosably distinct predictions, causing many studies of MHC to yield inconsistent or ambiguous results. We suggest a novel strategy to distinguish balancing versus divergent selection on MHC, taking advantage of natural admixture between parapatric populations. With divergent selection, immigrant alleles will be more infected and less fit because they are susceptible to novel parasites in their new habitat. With balancing selection, locally-rare immigrant alleles will be more fit (less infected). We tested these contrasting predictions using threespine stickleback from three replicate pairs of parapatric lake and stream habitats. We found numerous positive and negative associations between particular MHC IIβ alleles and particular parasite taxa. A few allele-parasite comparisons supported balancing selection, others supported divergent selection between habitats. But, there was no overall tendency for fish with immigrant MHC alleles to be more or less heavily infected. Instead, locally rare MHC alleles (not necessarily immigrants) were associated with heavier infections. Our results illustrate the complex relationship between MHC IIβ allelic variation and spatially varying multi-species parasite communities: different hypotheses may be concurrently true for different allele-parasite combinations.

scholarly journals The Domestication of Evolution

1983 ◽  
Vol 10 (4) ◽  
pp. 283-292 ◽  
Author(s):  
Raymond P. Coppinger ◽  
Charles Kay Smith
Keyword(s):  
Life History ◽  
Sexual Maturity ◽  
Domestic Animals ◽  
Stable Environment ◽  
In The Wild ◽  
Species Specific

A coming ‘Age of Interdependent Forms’ seems destined to mark the success of what could be called ‘despecialized/interspecific fitness’ among neotenic strains (perpetuating juvenile traits) of species such as humans and domestic animals. Humans as well as the first domesticants underwent a neotenic evolution in the wild during the repeated interglacial periods which, acting on a number of mammalian forms, selected against adult species-specific ancestral adaptations to a stable environment. Neotenic species continue to look and behave more like ancestral youths than adults—even after sexual maturity and throughout their life-history. As they retain lifelong youthful dependency motivations, they can easily, under suitable conditions, become interdependent forms. By the time of melting of the last Pleistocene glacier, all the domestic partners had already become more dependency-prone than formerly, and were behaviourally despecialized enough to form the alliance that is now changing the order of Nature.

scholarly journals Transposable Elements in the Organization and Diversification of the Genome of Aegilops speltoides Tausch (Poaceae, Triticeae)

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Olga Raskina
Keyword(s):  
Transposable Elements ◽  
Mobile Element ◽  
Plant Genome ◽  
Aegilops Speltoides ◽  
Genome Architecture ◽  
Different Types ◽  
In The Wild ◽  
Species Specific ◽  
Current Species

Repetitive DNA—specifically, transposable elements (TEs)—is a prevailing genomic fraction in cereals that underlies extensive genome reshuffling and intraspecific diversification in the wild. Although large amounts of data have been accumulated, the effect of TEs on the genome architecture and functioning is not fully understood. Here, plant genome organization was addressed by means of cloning and sequencing TE fragments of different types, which compose the largest portion of the Aegilops speltoides genome. Individual genotypes were analyzed cytogenetically using the cloned TE fragments as the DNA probes for fluorescence in situ hybridization (FISH). The obtained TE sequences of the Ty1-copia, Ty3-gypsy, LINE, and CACTA superfamilies showed the relatedness of the Ae. speltoides genome to the Triticeae tribe and similarities to evolutionarily distant species. A significant number of clones consisted of intercalated fragments of TEs of various types, in which Fatima (Ty3-gypsy) sequences predominated. At the chromosomal level, different TE clones demonstrated sequence-specific patterning, emphasizing the effect of the TE fraction on the Ae. speltoides genome architecture and intraspecific diversification. Altogether, the obtained data highlight the current species-specific organization and patterning of the mobile element fraction and point to ancient evolutionary events in the genome of Ae. speltoides.

bHLH transcription factor MyoD affects myosin heavy chain expression pattern in a muscle-specific fashion

2001 ◽  
Vol 280 (2) ◽  
pp. C408-C413 ◽  
Author(s):  
David J. Seward ◽  
John C. Haney ◽  
Michael A. Rudnicki ◽  
Steven J. Swoap
Keyword(s):  
Gene Expression ◽  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Biceps Brachii ◽  
Bhlh Transcription Factor ◽  
Hindlimb Unweighting ◽  
Protein Pool ◽  
In The Wild ◽  
Myod Gene ◽  
Mhc Iib

A strong correlative pattern between MyoD gene expression and myosin heavy chain IIB (MHC IIB) gene expression exists. To test whether this correlative relationship is causative, MHC gene expression in muscles from MyoD(−/−) mice was analyzed. The MHC IIB gene was not detectable in the MyoD(−/−) diaphragm, whereas the MHC IIB protein made up 10.0 ± 1.7% of the MHC protein pool in the wild-type (WT) mouse diaphragm. Furthermore, the MHC IIA protein was not detectable in the MyoD(−/−) biceps brachii, and the MHC IIB protein was overexpressed in the masseter. To examine whether MyoD is required for the upregulation of the MHC IIB gene within slow muscle after disuse, MyoD(−/−) and WT hindlimb musculature was unweighted. MyoD(−/−) exhibited a diminished response in the upregulation of the MHC IIB mRNA within the soleus muscle as a result of the hindlimb unweighting. Collectively, these data suggest that MyoD plays a role in the MHC profile in a muscle-specific fashion.

scholarly journals Assessing the Psychological Priorities for Optimising Captive Asian Elephant (Elephas maximus) Welfare

Animals ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 39 ◽  
Author(s):  
Jake Stuart Veasey
Keyword(s):  
Cognitive Processes ◽  
Management Strategies ◽  
Asian Elephant ◽  
Evolutionary Significance ◽  
Identification System ◽  
Asian Elephants ◽  
In Captivity ◽  
In The Wild ◽  
Human Care ◽  
Species Specific

The welfare status of elephants under human care has been a contentious issue for two decades or more in numerous western countries. Much effort has gone into assessing the welfare of captive elephants at individual and population levels with little consensus having been achieved in relation to both the welfare requirements of captive elephants, or their absolute welfare status. A methodology capable of identifying the psychological priorities of elephants would greatly assist in both managing and assessing captive elephant welfare. Here, a Delphi-based Animal Welfare Priority Identification System© (APWIS©) is trialled to evaluate the reliability of the methodology and to determine the welfare significance of individual behaviours and cognitive processes for Asian elephants (Elaphus maximus). APWIS© examines the motivational characteristics, evolutionary significance and established welfare impacts of individual behaviours and cognitive processes of each species being assessed. The assessment carried out here indicates appetitive behaviours essential for survival in the wild, together species-specific social and cognitive opportunities are likely to be important to the welfare of Asian elephant in captivity. The output of this assessment, for the first time, provides comprehensive species-specific psychological/welfare priorities for Asian elephants that should be used to inform husbandry guidelines, habitat design and management strategies and can also provide a valuable reference tool for Asian elephant welfare assessment. The effective application of these insights could lead to substantive improvements in captive Asian elephant welfare.

Multiple sclerosis: MHC associations and therapeutic implications

2005 ◽  
Vol 7 (3) ◽  
pp. 1-17 ◽  
Author(s):  
Samantha Holmes ◽  
Manuel A. Friese ◽  
Christian Siebold ◽  
E. Yvonne Jones ◽  
John Bell ◽  
...  
Keyword(s):  
Multiple Sclerosis ◽  
Major Histocompatibility Complex ◽  
T Cell Receptors ◽  
Molecular Basis ◽  
Structural Studies ◽  
Specific Level ◽  
Therapeutic Implications ◽  
Mhc Molecules ◽  
Histocompatibility Complex ◽  
Mhc Alleles

Multiple sclerosis (MS) is an autoimmune disease with an important genetic component. The strongest genetic association is with the major histocompatibility complex (MHC) region. Several MHC alleles predispose to the disease, the most prominent of which are certain alleles in the HLA-DR2 haplotype. Functional and structural studies have helped to explain the molecular basis of these associations. Although there is currently no curative treatment for MS, an increased understanding of the disease has aided the design of immunotherapies that act on the immune system more specifically than the longstanding drugs. Many of these therapies work at the antigen-specific level, disrupting the interaction between T-cell receptors and MHC molecules that leads to disease.

Development of a diagnostic molecular marker for Philonema spp. (Nematoda; Dracunculoidea) infecting salmonids in British Columbia

1995 ◽  
Vol 52 (S1) ◽  
pp. 129-133 ◽  
Author(s):  
L. Després ◽  
M.L. Adamson ◽  
T.E. McDonald
Keyword(s):  
British Columbia ◽  
Sockeye Salmon ◽  
Pcr Amplification ◽  
Base Substitution ◽  
Rainbow Trout Oncorhynchus Mykiss ◽  
Nematode Parasites ◽  
Rdna Sequences ◽  
Morphological Criteria ◽  
In The Wild ◽  
Species Specific

We developed a species specific DNA probe based on differential PCR amplification that distinguishes two congeneric nematode parasites of salmonids in British Columbia: Philonema agubernaculum Simon and Simon, 1936, usually parasitic in lake resident rainbow trout, Oncorhynchus mykiss; and P. oncorhynchi Kuitunen-Ekbaum, 1933, parasitic in anadromous sockeye salmon, O. nerka. The region differentially amplified was the D3 expansion domain of the 28S rDNA. Sequences of the two species differ in two parts of the domain, one a single base substitution and the other a three base duplication in P. oncorhynchi. A primer specific to P. oncorhynchi (amplifying P. oncorhynchi, not P. agubernaculum) was defined in the duplication region. Using differential amplification, we showed that sockeye smolts are infected with P. agubernaculum, although returning adults harbour only P. oncorhynchi. This technique could conceivably be used to quantify the frequency of heterologous infections in the wild, before infecting worms are identifiable at the species level based on morphological criteria.

An intergeneric hybrid in the family Phocoenidae

1998 ◽  
Vol 76 (1) ◽  
pp. 198-204 ◽  
Author(s):  
Robin W Baird ◽  
Pamela M Willis ◽  
Tamara J Guenther ◽  
Paul J Wilson ◽  
Bradley N White
Keyword(s):  
Dna Sequences ◽  
Parental Species ◽  
Intergeneric Hybrid ◽  
Harbour Porpoise ◽  
Colour Pattern ◽  
Phocoena Phocoena ◽  
Female Fetus ◽  
The Family ◽  
In The Wild ◽  
Species Specific

A 60-cm female fetus recovered from a Dall's porpoise (Phocoenoides dalli) found dead in southern British Columbia was fathered by a harbour porpoise (Phocoena phocoena). This is the first report of a hybrid within the family Phocoenidae and one of the first well-documented cases of cetacean hybridization in the wild. In several morphological features, the hybrid was either intermediate between the parental species (e.g., vertebral count) or more similar to the harbour porpoise than to the Dall's porpoise (e.g., colour pattern, relative position of the flipper, dorsal fin height). The fetal colour pattern (with a clear mouth-to-flipper stripe, as is found in the harbour porpoise) is similar to that reported for a fetus recovered from a Dall's porpoise to off California. Hybrid status was confirmed through genetic analysis, with species-specific repetitive DNA sequences of both the harbour and Dall's porpoise being found in the fetus. Atypically pigmented porpoises (usually traveling with and behaving like Dall's porpoises) are regularly observed in the area around southern Vancouver Island. We suggest that these abnormally pigmented animals, as well as the previously noted fetus from California, may also represent hybridization events.

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