Literatura científica selecionada sobre o tema "Polymorphisme alaire"

Abstract Honey bee populations from the island of Cyprus were analyzed using microsatellite and mitochondrial DNA markers. A total of 268 colonies were sampled in Cyprus, at six different locations-Kyrenia, Katydata, Flassou, Alabra, Troulloi, and Alassa-covering a wide area of the island. Results showed that the Cyprian honey bee Apis mellifera cypria could be distinguished from other Apis mellifera subspecies based on a „double pattern“ of mitochondrial DNA belonging to the C1 lineage and microsatellite DNA belonging to the O lineage. All populations were homogeneous, except the population from Kyrenia, probably due to the introduction of queens or colonies belonging to the C2, C6, and M7 lineages.

Les supergènes, des régions génétiques où des loci coadaptés sont transmis comme une seule unité mendélienne, jouent un rôle crucial dans la mise en place des polymorphismes complexes mais démêler la complexité de leur évolution et de leur maintien reste un défi de taille. Les fourmis offrent un contexte unique pour mettre en évidence de nouveau supergènes et étudier les principes généraux régissant leur mise en place et leur évolution puisqu'elles présentent de grandes variations inter et intra-espèces dans tous les aspects de leur organisation sociale et qu'un nombre inhabituellement élevé de supergènes a déjà été mis en évidence dans différentes espèces. Notamment, dans cinq lignées différentes un supergène en lien avec l'organisation sociale des colonies, c'est-à-dire le nombre de reines accouplées par colonie, a été mis en évidence. Cependant, son origine et son maintien restent à élucider clairement et de nouveaux modèles sont nécessaires. L'espèce de fourmi Myrmecina graminicola suscite un intérêt particulier pour l'étude des supergènes chez les insectes sociaux puisqu'elle présente à la fois un polymorphisme social (présence de colonies monogynes et de colonies polygynes) et un polymorphisme alaire (présences de reines ailées et de reines aptères).Dans cette thèse, nous avons exploré la présence de supergènes chez M. graminicola, en lien notamment avec ces deux polymorphismes. Dans le premier chapitre, à l'aide de données de reséquençage, nous avons mis en évidence la présence d'un supergène lié au polymorphisme social (~10 Mb) daté de ~1 Ma en déséquilibre de liaison avec un supergène lié au polymorphisme alaire (~110 kb) apparu plus récemment (~ 0,4 Ma). Dans le deuxième chapitre, nous avons étudié les liens entre les traits d'histoire de vie des deux principaux types de colonies retrouvés dans cette espèce, à savoir les colonies monogynes avec des reines ailées et les colonies polygynes avec des reines aptères. Nous avons montré que ces deux types de colonies ne différaient pas quant au nombre d'ouvrières et de larves au moment de l'échantillonnage. Une fois élevées en laboratoire, nous avons observé que ces deux types de colonies produisaient un nombre similaire de nymphes et d'adultes mais que les colonies polygynes produisaient plus d'œufs et de nouvelles larves que les colonies monogynes. Dans le troisième chapitre, nous avons exploré la possibilité qu'il existe dans cette espèce d'autres supergènes non liés directement à la socialité ou à la présence/absence d'ailes. Nous avons identifié un troisième supergène (~7 Mb) et démontré qu'il n'était pas associé au sex ratio des colonies. Dans l'ensemble, cette thèse révèle la présence de trois supergènes chez la fourmi M. graminicola, dont un lié au polymorphisme social, un autre au polymorphisme alaire, et propose des pistes sur les mécanismes contribuant au maintien de ces polymorphismes<br>Supergenes, genetic regions where coadapted loci are inherited as a single Mendelian unit, play a crucial role in establishing complex polymorphisms. However, unraveling the complexity of their evolution and maintenance remains a significant challenge. Ants offer a unique context to identify new supergenes and study the general principles governing their establishment and evolution due to their extensive inter- and intra-species variations in all aspects of social organization. Notably, in five different lineages, a supergene related to colony social organization, specifically the number of mated queens per colony, has been identified. However, its origin and maintenance remain to be clearly elucidated, and new models are needed. The ant species Myrmecina graminicola is of particular interest for studying supergenes in social insects as it exhibits both social polymorphism (presence of monogynous and polygynous colonies) and wing polymorphism (presence of winged and apterous queens).In this thesis, we explored the presence of supergenes in M. graminicola, particularly in relation to these two polymorphisms. In the first chapter, using resequencing data, we identified a supergene associated with social polymorphism (~10 Mb) dating back to ~1 Mya, in linkage disequilibrium with a supergene linked to wing polymorphism (~110 kb) that appeared more recently (~0.4 Mya). In the second chapter, we examined the life history traits of the two main types of colonies found in this species, namely monogynous colonies with winged queens and polygynous colonies with apterous queens. We showed that these two colony types did not differ in the number of workers and larvae at the time of sampling. When reared in the laboratory, we observed that both types of colonies produced a similar number of nymphs and adults but that polygynous colonies produced more eggs and new larvae than monogynous colonies. In the third chapter, we explored the possibility of other supergenes in this species not directly linked to sociality or wing presence/absence. I identified a third supergene (~7 Mb) and demonstrated that it was not associated with colony sex ratio. Overall, this thesis reveals the presence of three supergenes in the ant M. graminicola, one linked to social polymorphism, another to wing polymorphism, and provides insights into the mechanisms contributing to the maintenance of these polymorphisms

A clear and predictive understanding of the propensity for crystallisation of one polymorph over another is lacking, and in this regard glycine is a model system due to difficulties in crystallisation of the thermodynamically stable gamma polymorph. The preferential crystallisation of gamma-glycine in the presence of micellar CTAB (Cetyltrimethylammonium bromide) as opposed to the alpha form commonly crystallised from pure solution was observed. A rationale for this result was sought through the observation of the nucleation and growth kinetics of the alpha and gamma polymorphs of glycine (and DL-alanine) using in situ microscopy, the measurement of induction times and following the solution mediated phase transformation of alpha-glycine. These observations help explain the dominant crystal form produced in a number of solutions. The nucleation and growth rates of alpha-glycine were shown to be orders of magnitude greater than those of gamma-glycine in pure solution. Also, the addition of a cationic surfactant (such as CTAB) or modification of the solution pH were shown to dramatically accelerate the nucleation and growth of polar gamma-glycine and DL-alanine, a rarely reported phenomenon. In addition, the growing (00-1) faces of gamma-glycine and DL-alanine, at which growth was accelerated, were shown to be macroscopically rough, indicating a growth mechanism dominated by nucleation rather than the growth of layers. The most likely cause of the inhibited kinetics of gamma-glycine and DL-alanine is water bound electrostatically at the negatively charged (00-1) faces, while the growth acceleration inferred by the additives is related to their ability to release water from these surfaces. Other mechanisms which may play a role include the adsorption of adventitious impurities, strong electrostatic repulsion between like-charged carboxylate groups at the (00-1) surface resulting in structural disorder, and the effect of surface energy on the rate of surface nucleation. This research provides an important example of nature’s complexity in selecting crystal form in polymorphic systems, gives further insight into the causes of the asymmetric growth of polar crystal structures, and introduces the possibility that the crystallisation kinetics of ‘difficult’ slow growing compounds may sometimes be modified through the use of additives.

The epitope of a mouse monoclonal AB (9.9) which detects a Factor IX (F.IX) polymorphism in the plasma of normal persons (PNAS 82:3839, 1985) has been related to not more than 6 AA residues of F.IX by recombinant DNA technology. The same 6 residues define Smith’s polymorphic epitope (Am. J. Human Genet. 37:688, 1985 and in press). This region of F.IX contains the alanine:threonine dimorphism at residue 148 first suggested by McGraw et al. (PNAS 82: 2847, 1985) and established by Winship and Brownlee with synthetic DNA oligomers (Lancet in press). Using synthetic DNA probes, we have found that the DNA difference between positive and negative reactors to 9.9 is whether base pair 20422, the first pair in the codon for residue 148, is A:T or G:C. We can conclude that 9.9 reacts with F.IX containing threonine but not alanine at position 148.The F.IX immunologic polymorphism-whose epitope we are referring to as “Malmo”-is, not surprisingly, in strong linkage disequilibrium with two F.IX DNA polymorphisms, TaqI and Xmnl. The highest frequency of the rarer Malmo allele in 6 disparate ethnic groups was in Swedes (32%); a lower frequency (14%) was seen in White Americans whose ancestors came overwhelmingly from the Celtic regions of the British Isles; it was at very low frequency or absent in Black Americans, East Indians, Chinese and Malays. A maximum frequency in Swedes and absence in Africans and Orientals suggest that the transition from A:T to G:C occurred in Scandinavia and spread from there. The history of Europe and America plus the geographical distribution of the rare allele lead us to suggest that this locus might be designated: “the Viking gene”.

Small differences in spectral peak among cone pigments appear to underlie several different human color vision polymorphisms. We recently identified three amino acid substitutions that can account for spectral differences among X-encoded pigments. Each of these appears to produce spectral shifts of specific magnitudes. The one that produces the smallest spectral shift (5–7 nm) is a serine for alanine substitution at amino acid position 180. This substitution may be responsible for cone pigment variations among color normal observers (Science, 252, p. 971). We have tested the hypothesis that this same substitution causes spectral variation in the M pigments of protanopes. Spectral sensitivities of protanopes were measured using ERG flicker photometry. We found two types of protanope (in a sample of seven); one phenotype has an M pigment with a spectral peak of 530 nm and the other has a pigment with a 537-nm peak. The amino acid sequences of the M pigments, deduced from nucleotide sequences of genes from one of each of the two protanope phenotypes, differ at position 180 just as predicted. These results confirm that this substitution produces a 5–7-nm shift in human cone pigments. Several different color vision polymorphisms may be caused by this single substitution.

Congenital deficiencies of the fibrinolytic inhibitor α2antiplasmin (α2AP) may result in bleeding disorders. An abnormal a AP (α2AP‘Enschede’) is known. 2 siblings with 3% functional activity and normal antigen level have parents with 50% activity and normal antigen. The protein interacts normally with the lysine-binding site(s) of plasmin(ogen) but does not inhibit plasmin irreversibly. α2AP Enschede is a plasmin substrate that like the normal protein releases a M 8,000 peptide upon reaction with plasmin. In the present study, Southern blot analysis, using an α2AP cDNA probe showed a restriction fragment length polymorphism within a small genomic DNA fragment of the Enschede family members. Cloning and sequencing of these fragments revealed a GCG inframe insertion that results in an alanine addition between amino acids 353 and 357, 7-10 positions NH -terminal to the reactive site PI residue, Arg364. This area is homologous to the A4 B-sheet of reactive site cleaved a -antitrypsin. Clones from each individual confirm the parents as true heterozygotes and the children as true homozygotes. A cloned genomic DNA sequence containing the insertion (V ) was exchanged for the normal sequence in a eukaryotic a AP expression plasmid. Recombinant α2AP‘Enschede’ (ra AfVAla) purified from the conditioned media of transfected Chinese Hamster Ovary Cells is analogous to plasma a α2AP‘Enschede’ with respect to interactions with plasmin and plasminogen. Preliminary analysis of the released Mr 8,000 recombinant peptide shows that its NH -terminus is the same as the peptide cleaved from normal a AP. Although ra α2APVAla does not inhibit plasmin irreversibly it does, however, act as a competitive inhibitor of hydrolysis of the chromogenic substrate S-2251 by plasmin.The K for this interaction is 25 nM. Thus, α2APAla retains a high affinity for the active center of plasmin. In conclusion, an Ala insertion near the reactive site of α2AP must have resulted in a structural perturbation that has abolished the plasmin inhibitory activity of a α2AP‘Enschede’. This variant may provide a model for further investigation of structure-function relationships in the serpins which determine the relative inhibitor vs. substrate properties.

Long-term exposure to fluorides on the body of aluminum production workers is a determining factor in the development of chronic occupational intoxication with fluorine compounds, the pathogenetic mechanisms of which have not been studied enough. The systemic aspects of its course remain open. The aim — on the basis of experimental and clinical genetic data to study the medical and biological aspects of the formation of metabolic maladaptation in the dynamics of fluoride intoxication. Material and methods. The study included 370 metallurgists with occupational pathology and a comparison group, n=127, with individual signs of fluorine exposure to the skeleton. Bone mineral density was studied. Real-time PCR evaluated the association of VEGF and GST gene polymorphisms with the risk of developing intoxication, diseases of the circulatory system, liver pathology, and renal dysfunction. The experiment was simulated with 12 weeks of free access of rats, n=130, to NaF solution, 10 mg/l. Western-blot analysis in the cytosolic fraction of the liver, kidneys, heart studied the level of HIF‑1α, HSP72, HSC73, HOx‑1,2. In the blood plasma and homogenate of the studied organs, the activity of metabolic enzymes was determined: alkaline and acid phosphatases, α-glycerophosphate dehydrogenases, alanine-, aspartate aminotransferases, cholinesterases, γ-glutamyltranspeptidase, catalase, superoxide dismutase lactate-, hydroxybutyratedehydrogenases. Results. A clinical and experimental study showed the development of specific metabolic changes in the dynamics of fluoride intoxication and their relationship with degenerative-dystrophic changes in the skeleton. The association of the GC VEGF, GSTT1, M1 0/0 genotype with the risk of developing comorbid pathology was determined. The experiment shows that the response to NaF develops in waves. In the early stages, the expression of protective proteins and metabolic enzymes in hepatocytes increases. Compensatory reactions are provided by increased cytochemical activity. From the 6th week, the structure of the liver and kidneys is disturbed. In the heart of rats, activation of the redox signaling system and antioxidant protection was noted, which reduces the intensity of free radical processes and preserves the structure of the myocardium up to the 3rd week. Further, the imbalance of compensatory mechanisms is determined against the background of activation of free radical oxidation, degenerative changes in cardiomyocytes, 9 weeks. Conclusions. The leading pathogenetic link in the formation of a chain of systemic pathological reactions in fluoride intoxication is maladaptive shifts in homeostasis parameters associated with individual risk.