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At least 73 records · Page 4Linked to original sources
PubMed1990

Comparative structure and evolution of murine CR2. The homolog of the human C3d/EBV receptor (CD21).

The complete nucleotide sequence of murine complement receptor type 2 (CR2) was determined from two overlapping cDNA clones derived from a lambda gt11 library of late pre-B cell origin. Comparison of the predicted sequence of the 1014 amino acid murine homolog with that of human CR2 revealed marked evolutionary conservation. The murine molecule was 65% identical to human CR2 overall, lacking a single repetitive sequence variably present in man. The 15 approximately 60-75 amino acid short consensus repeats (SCR) that constitute the entire extracellular domain of murine CR2 were 53 to 81% identical to and could be directly aligned with the human protein. As reported, the cytoplasmic tail shared 79% amino acid identity with human CR2, whereas that of the transmembrane was only 33%. Murine CR2 contained 16 potential N-linked glycosylation sites of which 6 were conserved, 4 altered, and 6 lost during human evolution. The hydropathicity profile of the two molecules was nearly colinear with some variation in the N-terminal region of the first repeat, as well as within the sixth and twelfth repeats. RNA blot analysis revealed a approximately 4.0 to 5.0 kb message in murine B lymphocytes, which was absent in T lymphocytes (thymus and spleen), liver, brain, lung, kidney, and heart. A method was devised to more precisely compare the repeat structures. An identity matrix analysis suggests that human ancestral CR2 evolved before divergence of the rodent and primate branches of the evolutionary tree through a series of predictable gene duplications, possibly giving rise to the precursor of human CR1 and murine CRY. The marked structural similarity between the human and murine receptors suggests functional conservation as well.

Amino Acid Sequence↗
PubMedDate not supplied

[Comparative clinico-evolutive and therapeutic aspects in cancer of the right and left colon].

The paper reports on the casuistics of the colon cancer in the Clinic of Surgery of the "Griviţa" Clinical Hospital, for 21 years (1966-1986) with emphasis on the situs peculiarities on the right and left colon. Whereas the left colon cancer (LCC) started in 32% of cases with subocclusive and occlusive syndromes having special implications on the treatment and prognosis, in the right colon cancer (RCC) only in 3.5% of cases the diagnosis was established in the stage of subocclusive syndrome. During surgery the metastatic adenopathy was met in 57% in LCC and only in 37% in RCC, and the hepatic metastases in 17.7% in LCC and in 10.9% in the RCC cases. The immediate postsurgery mortality was present in 12% of the LCC cases and in only 9.3% of the RCC cases. In the last 10 years of the period studied, the patients were periodically readmitted into the hospital, reinvestigated, and monochemotherapy with 5-fluorouracil was applied in sequential cures. In this last period, the survival at 5 years was of 25 (45.4%) in the 55 patients operated for RCC and of 41 (37.6%) in the 109 patients operated for LCC.

Aged↗
PubMed1979

Quantitation of gastrin and somatostatin cell populations in the antral mucosa of the rat. Comparative distribution and evolution through different life stages.

Total antral gastrin and somatostatin cell populations as well as their relative distribution pattern throughout the antrum were studied in rats with advancing age from birth time to old age. Both endocrine cell populations were estimated, after staining by immunoperoxidase technique, with a quantitative method using serial parallel strips from entire stomachs. Gastrin cells were regularly found at less than 1 h of post-natal life, but were few in number (447 +/- 82) cells. Somatostatin cells, not seen at birth, were observed in all rats at seven post-natal days; then they increased in number less rapidly but more regularly than gastrin cells. During the normal adult period, corrected gastrin cell population corresponds to about 330,000-500,000 cells and corrected somatostatin cell populations to about 130,000-200,000 cells. For the whole antrum the ratio of gastrin cell to somatostatin cell populations decreases through the rat life from 6.5 at 7 days to 1.5 in old age with a stable value, 2.5, during adult period. Examination of the topographical distribution throughout the antrum of these two populations shows that, strip per strip, their numerical ratio varies. Homogeneous values for the latter occur in the middle part of antrum and, as rule, in each group they reflect the mean value calculated for the whole of the antrum.

Aging↗
PubMed1986

Comparative morphology and evolution of cheek pouches in rodents.

There are two types of cheek pouches in extant rodents. Internal cheek pouches are evaginations of the oral cavity deep to M. platysma and M. sphincter colli profundus, and have evolved independently in some species of the superfamilies Sciuroidea and Muroidea. External, furlined cheek pouches open lateral to and separate from the oral cavity, (also deep to M. platysma and M. sphincter colli profundus), and occur in all species of the families Geomyidae and Heteromyidae. The presence of external, furlined cheek pouches is a synapomorphy for the superfamily Geomyoidea. The posterior retractor muscle of the pouch is derived from facial musculature in sciurids, from trapezius musculature in cricetids, and from both facial and trapezius muscle groups in the Geomyoidea. Differences also exist in the musculature associated with the pouch opening. In the Sciuridae and Cricetidae, the M. buccinatorius muscle group acts as a sphincter to control the size of the pouch opening. In the Geomyoidea, the size of the opening is controlled by the M. orbicularis sacculi in concert with a slip of the M. platysma myoides. Thin sections and scanning electron micrographs of the pouch tissue reveal the presence of dermal papillae in Phodopus sungorus but not in a close relative, Mesocricetus auratus. All members of the subfamily Cricetinae have a peninsula of highly folded tissue projecting anteriorly from the posteromedial pouch wall. This folding allows for expansion of the pouch walls when food is stored in the pouch.

Animals↗
PubMedDate not supplied

Experimental evaluation of rigor mortis. III. Comparative study of the evolution of rigor mortis in different sized muscle groups in rats.

The use of new methods and an appropriate apparatus has allowed us to make successive measurements of rigor mortis and a study of its evolution in the rat. By a comparative examination on the front and hind limbs, we have determined the following: (1) The muscular mass of the hind limbs is 2.89 times greater than that of the front limbs. (2) In the initial phase rigor mortis is more pronounced in the front limbs. (3) The front and hind limbs reach maximum rigor mortis at the same time and this state is maintained for 2 hours. (4) Resolution of rigor mortis is accelerated in the front limbs during the initial phase, but both front and hind limbs reach complete resolution at the same time.

Animals↗
PubMed2026

Comparative Genomics Reveals Convergent Evolution Between Avivorous Bats (Ia io and Nyctalus aviator).

Investigating the genetic basis of dietary specialization can provide insights into the evolution of niche breadth. In this study, we employed comparative genomics to investigate the adaptive mechanisms enabling two bat species (Nyctalus aviator and Ia io) to shift from insectivory to seasonal bird consumption (avivorous bats). Our findings revealed adaptation related to immune response and lipid metabolism in avivorous bat species. Avivorous bats exhibit strong positive selection and convergent evolution in immune-related genes, which are under heightened selective pressure compared to those of non-avivorous bats. These species also display significantly fewer endogenous retroviral elements. These findings emphasized the significance of immune-driven adaptive evolution in avivory. Additionally, our results showed that the dietary evolution of avivorous bats is accompanied by convergent evolution associated with the lipid metabolism. Notably, CEPT1, the upstream gene required for the activation of the PPAR pathway, underwent positive selection and convergence, which may have affected lipid metabolism. These adaptations may enable avivorous bat species to face the challenge of immune response and nutrition during dietary niche expansion. These findings not only provide comprehensive insights into the adaptive evolution driving the unique diet of avivorous bats but also offered novel perspectives on the molecular mechanisms underlying ecological niche evolution in a dietary context.

Animals↗
PubMed1977

Takeover mechanisms and early biochemical evolution.

It is common feature of comparatively recent evolution that a structure adapted to one function turns out also to have another function, or another way of performing an existing one. It is proposed that while our central biochemical machinery was actively evolving there were such discoveries and takeovers that provided routes to radically new disigns. The recognition and control techniques of protein would seem to be replacements for earlier approaches to similar functions. Polynucleotides may have been more widely used here in a pre-protein era. But even nucleic acid is seen as the outcome of a takeover, from an earlier quite different genetic material with properties more appropriate to primitive conditions and to primitive techniques of molecular control.

Biological Evolution↗
PubMed2024

Repeated evolution on oceanic islands: comparative genomics reveals species-specific processes in birds.

Understanding the interplay between genetic drift, natural selection, gene flow, and demographic history in driving phenotypic and genomic differentiation of insular populations can help us gain insight into the speciation process. Comparing patterns across different insular taxa subjected to similar selective pressures upon colonizing oceanic islands provides the opportunity to study repeated evolution and identify shared patterns in their genomic landscapes of differentiation. We selected four species of passerine birds (Common Chaffinch Fringilla coelebs/canariensis, Red-billed Chough Pyrrhocorax pyrrhocorax, House Finch  Haemorhous mexicanus and Dark-eyed/island Junco Junco hyemalis/insularis) that have both mainland and insular populations. Changes in body size between island and mainland populations were consistent with the island rule. For each species, we sequenced whole genomes from mainland and insular individuals to infer their demographic history, characterize their genomic differentiation, and identify the factors shaping them. We estimated the relative (Fst) and absolute (dxy) differentiation, nucleotide diversity (π), Tajima's D, gene density and recombination rate. We also searched for selective sweeps and chromosomal inversions along the genome. All species shared a marked reduction in effective population size (Ne) upon island colonization. We found diverse patterns of differentiated genomic regions relative to the genome average in all four species, suggesting the role of selection in island-mainland differentiation, yet the lack of congruence in the location of these regions indicates that each species evolved differently in insular environments. Our results suggest that the genomic mechanisms involved in the divergence upon island colonization-such as chromosomal inversions, and historical factors like recurrent selection-differ in each species, despite the highly conserved structure of avian genomes and the similar selective factors involved. These differences are likely influenced by factors such as genetic drift, the polygenic nature of fitness traits and the action of case-specific selective pressures.

Animals↗
PubMed1982

Antigenic conservation of brain guanylate cyclase during evolution.

A comparative study of brain guanylate cyclase from different animal species (including man, bird, fish and amphibian) has been performed using a specific antibody directed against soluble rat brain guanylate cyclase. Analyses were performed on supernatant fractions by the double-immunodiffusion test, by the protein blotting technique after SDS-polyacrylamide gel electrophoresis and by analytical isoelectric focusing on agarose allowing specific immunodetection of isoelectric patterns. Membrane-bound guanylate cyclase from rat brain and soluble guanylate cyclase from several rat tissues cross-reacted with the antibody. All the brain enzymes tested were found to be identical by double-immunodiffusion. The electrophoretic and isoelectrophoretic profiles of the different brain guanylate cyclases were found to exhibit many common features with some differences between mammalian and non-mammalian enzymes. In human brain, guanylate cyclase has been localized in glial and neuronal cells by immunohistochemistry. The results demonstrate that guanylate cyclase has been well conserved during the course of evolution and are consistent with the involvement of guanylate cyclase and cyclic GMP in basic cellular function.

Animals↗
PubMed1990

Traumatic aphasia in children and adults: a comparison of clinical features and evolution.

We compared the performance on test of language, apraxia, acalculia and intelligence of 32 children--age 5 to 16 years--and 31 adults, seen at our Aphasia Unit for the sequelae of a brain trauma. Logorrhea was never present among children who had nonfluent aphasia more frequently than adults. Apraxia and acalculia were equally present in the two groups. Twelve children and 15 adults of the first study were retested at variable distance from trauma. No group difference was found in the recovery of auditory comprehension (Token Test) or oral expression (oral confrontation naming and telling-of-an-event). On a battery of verbal and spatial memory tests 6 of the 12 children had pathological scores in one or more tests. Scholastic achievements were compared with those of the nearest kin. We conclude that while aphasia profiles are different in children and adults, the incidence of apraxia and acalculia and the recovery rate do not discriminate the two groups.

Achievement↗
PubMed1976

Comparative study of plasma cortisol evolution in TRH or placebo injected patients with or without thyroid disease.

The plasma cortisol evolution under TRH has been compared in 27 euthyroid, 12 hyperthyroid and 5 patients with hot nodules and in 15 control individuals receiving a placebo or sham injection. The results showed no statistical difference in plasma cortisol evolution between the groups, suggesting no influence of the thyroid status or TSH secretion on the spontaneous fall of cortisol level during the time of the test.

Clinical Trials as Topic↗