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PubMed2002

Modelling the evolution of female choice strategies under inbreeding conditions.

Recently, many mate choice studies have discussed the role of genetic compatibility and inbreeding for the evolution of mate choice. With population genetic simulations I compared the potential advantage of three different female choice strategies under inbreeding conditions. Females were assumed to benefit indirectly via a preference for (i) complementary males, (ii) males with few detrimental mutations, and (iii) non-inbred males. Probably related to the reduced inbreeding depression in offspring of choosy females, the choice-allele increased for all three strategies. However, the advantage of the strategies differed widely. Choice of males with fewer mutations provided a comparatively large advantage, choice of complementary males led to a reasonable advantage, and choice of non-inbred males only resulted in a minor advantage of female choice. My results show that complementary mate choice can be almost as beneficial as conventional good-genes choice of mates with lower genetic load. Compared to the two other mate choice strategies, choice of non-inbred males is less likely to contribute to the evolution of costly mate choice. The results of a recent study showing that female sticklebacks prefer males with a larger number of MHC-loci is thus unlikely to be related to an indirect benefit of choosing non-inbred males.

Animals↗
PubMed1998

Can weighting improve bushy trees? Models of cytochrome b evolution and the molecular systematics of pipits and wagtails (Aves: Motacillidae).

Among-site rate variation (alpha) and transition bias (kappa) have been shown, most often as independent parameters, to be important dynamics in DNA evolution. Accounting for these dynamics should result in better estimates of phylogenetic relationships. To test this idea, we simultaneously estimated overall (averaged over all codon positions) and codon-specific values of alpha and kappa, using maximum likelihood analyses of cytochrome b data from all genera of pipits and wagtails (Aves: Motacillidae), and six outgroup species, using initial trees generated with default values. Estimates of alpha and kappa were robust to initial tree topology and suggested substantial among-site rate variation even within codon classes; alpha was lowest (large among-site rate variation) at second-codon and highest (low among-site rate variation) at third-codon positions. When overall values were applied, there were shifts in tree topology and dramatic and statistically significant improvements in log-likelihood scores of trees compared with the scores from application of default values. Applying codon-specific values resulted in yet another highly significant increase in likelihood. However, although incorporating substitution dynamics into maximum likelihood, maximum parsimony, and neighbor-joining analyses resulted in increases in congruence among trees, there were only minor improvements in phylogenetic signal, and none of the successive approximations tree topologies were statistically distinguishable from one another by the data. We suggest that the bushlike nature of many higher-level phylogenies in birds makes estimating the dynamics of DNA evolution less sensitive to tree topology but also less susceptible to improvement via weighting.

Animals↗
PubMed1990

Trypanosoma (Schizotrypanum) cruzi: repetitive DNA sequence evolution in three geographically distinct isolates.

1. Middle-repetitive DNA sequences were analyzed by molecular hybridization to determine both the extent of complementarity and time of evolutionary divergence between isolates of Trypanosoma cruzi from Argentina, Mexico, or Venezuela. 2. Although molecular hybridizations showed no significant difference between the middle-repetitive DNAs of the Mexican and Venezuelan isolates, there was a 2.7% base pair mismatch in hybrid molecules formed by association of strands from both the Mexican and Argentine isolates. 3. Using the rates for divergence of middle-repetitive DNA in sea urchins, the Mexican and Argentine isolates were estimated to have diverged approximately 20-25 million years ago. 4. Analysis of the kinetics for the DNA hybridizations indicates that only minor amplifications of specific gene sequences or changes in the complexity of the genomes could have occurred during the divergence of the three isolates studied.

Animals↗
PubMed1996

The age of Alu subfamilies.

Using Kimura's distance measure we have calculated the average age of all major Alu subfamilies based on the most recent available data. We conclude that AluJ sequences are some 26 Myr older than previously thought. Furthermore, the origin of the FLA (Free Left Arm) Alu family can be traced back to the very beginning of the mammalian radiation. One new minor subfamily is reported and discussed in the context of sequence diversity in major Alu subfamilies.

Animals↗
PubMed2005

Development of the pelvis and posterior part of the vertebral column in the Anura.

The anuran pelvic girdle is unique among all amphibians in that its acetabular portion is located far posterior to the sacrum, lateral to the postsacral (= caudal) vertebral column, which is reduced to a single rod-like element called the urostyle. This situation in the adult is strikingly different not only from that in ancestral temnospondyls but also in other modern amphibians. Because there is no fossil that would document this evolutionary anatomical modification except for Triadobatrachus, the only data may be inferred from development in modern anurans. We chose seven anuran species (belonging to the genera Discoglossus, Bombina, Pelobates, Bufo, Rana and Xenopus), representing the principal locomotory types (saltation, swimming, crawling and burrowing). Development of the pelvic girdle was studied on cleared and stained whole mounts and partly on serial histological sections. The basic developmental pattern was similar in all species: the pelvis on both sides develops from two centres (puboischiadic and iliac, respectively). The ilium then extends vertically towards the sacral vertebra and later rotates posteriorly so that ultimately the acetabulum is lateral to the tail (= urostyle). Only minor deviations from this pattern were found, mainly associated with differences in water and terrestrial dwelling.

Animals↗
PubMed2001

[The origin of femoral trochlear dysplasia: comparative anatomy, evolution, and growth of the patellofemoral joint].

We performed a comparative analysis of the femoropatellar morphology examining the evolutionary aspects to search for the origin of trochelar dysplasia. Trochlear dysplasia is frequent in the human population and, when associated with morphological and positional abnormalities of the patella, can lead to patellar pain syndrome in minor cases or patellar dislocation in severe cases. There is no strict relationship between the observed anomalies and clinical expression. The shape of the articular surfaces is variable in mammals depending on their type of locomotion: unguligrade, digitigrade, plantigrade. In greater apes, the femoral diaphysis is straight and the trochlea is flat and symmetrical. The patella does not tend to dislocate laterally since the knee under load is always flexed. In human adults, the femoral diaphysis has a valgus obliquity angle of 8 degrees to 10 degrees. Consequently, the trochlea has a deepened sulcus and an elevated lateral lip, avoiding lateral patellar dislocation, especially during initial knee flexion. In the human newborn, the femoral diaphysis is vertical. As the child starts walking, the femoral obliquity angle develops between 1 and 7 years of age, inducing a secondary valgus of the extensor apparatus. This obliquity does not develop in non-walking children. Fossil femurs of australopithecus demonstrate that a high obliquity angle had appeared more than 3 million years ago, but also exhibit a poorly deepened trochlea and a slight elevation of the lateral facet. At 1.8 million years, the fossils have the oblique diaphysis, the strongly deepened sulcus and the strongly elevated lateral facet. The obliquity angle of the femoral diaphysis is the leading feature which initiated the later modifications of the patellofemoral joint that over 3 million years were never inscribed in the human genoma. Lateral trochleal lip and deep sulcus are features that were first acquired, then once selected, genetically assimilated, and now appear on the fetal cartilaginous epiphysis.

Adult↗
PubMed2001

Evolution of functional diversity in the cupin superfamily.

The cupin superfamily of proteins is among the most functionally diverse of any described to date. It was named on the basis of the conserved beta-barrel fold ('cupa' is the Latin term for a small barrel), and comprises both enzymatic and non-enzymatic members, which have either one or two cupin domains. Within the conserved tertiary structure, the variety of biochemical function is provided by minor variation of the residues in the active site and the identity of the bound metal ion. This review discusses the advantages of this particular scaffold and provides an evolutionary analysis of 18 different subclasses within the cupin superfamily.

Amino Acid Motifs↗
PubMed1994

The role of extinction in evolution.

The extinction of species is not normally considered an important element of neodarwinian theory, in contrast to the opposite phenomenon, speciation. This is surprising in view of the special importance Darwin attached to extinction, and because the number of species extinctions in the history of life is almost the same as the number of originations; present-day biodiversity is the result of a trivial surplus of originations, cumulated over millions of years. For an evolutionary biologist to ignore extinction is probably as foolhardy as for a demographer to ignore mortality. The past decade has seen a resurgence of interest in extinction, yet research on the topic is still at a reconnaissance level, and our present understanding of its role in evolution is weak. Despite uncertainties, extinction probably contains three important elements. (i) For geographically widespread species, extinction is likely only if the killing stress is one so rare as to be beyond the experience of the species, and thus outside the reach of natural selection. (ii) The largest mass extinctions produce major restructuring of the biosphere wherein some successful groups are eliminated, allowing previously minor groups to expand and diversify. (iii) Except for a few cases, there is little evidence that extinction is selective in the positive sense argued by Darwin. It has generally been impossible to predict, before the fact, which species will be victims of an extinction event.

Animals↗
PubMed1985

[Current status of the surgery of carotid stenoses].

In a series of 472 operations performed in 420 patients between 1981 and 1982, the mortality rate was 1.1% in asymptomatic patients (stage 0) and 2.1% in patients with transient ischaemic attacks (stage I) or with minor neurological sequelae (stage III). The morbidity rate of serious sequelae was 1.05%. The long term mortality is 30% at 5 years and 50% at 10 years, in most of the major statistical studies. The major cause of death (more than 50%) is myocardial infarction. The study of the local evolution of the operated artery reveals that about 10% of the patients who survived between 5 to 10 years had a recurrent carotid artery stenosis. Comparative studies of the course of the atherosclerotic disease operated patients and in patients treated medically are difficult to evaluate. However, most authors agree with Fields that an operation is justified in asymptomatic patients and in those presenting transient ischaemic attacks, provided the mortality and morbidity rate is less than 3%. Finally, recent studies stress the value of non-invasive investigations for determining the prognosis of tight stenoses: in asymptomatic patients with tight stenoses, the risk of a cerebrovascular accident is 5 times greater than in patients with a minor stenosis.

Arteriosclerosis↗
PubMed1990

Discrimination between adaptive and neutral amino acid substitutions in vertebrate hemoglobins.

A discriminant analysis on the basis of the physicochemical properties of amino acid residues is developed to investigate the accumulation pattern of amino acid substitutions in a family of proteins. The application of this analysis to vertebrate hemoglobins reveals the following new results. (1) The major components of teleost fish and amphibian hemoglobins showing the Root effect are sharply discriminated from mammalian hemoglobins in several regions of the alpha and beta chains, whereas shark, minor components of teleost fish and amphibian, reptile, and bird hemoglobins showing no Root effect exhibit a gradual change to mammalian hemoglobin in a straightforward way. This result suggests at least two lines of molecular evolution in vertebrate hemoglobins. (2) The nonadult hemoglobin chains are allocated to the latter line, i.e., tadpole, zeta, and pi chains are similar to shark and trout I chains, and epsilon and gamma chains are similar to some of the reptile chains. (3) In any case, most of the amino acid residues causing the discrimination are located near the sites that carry the amino acid residues conserved well throughout all classes of vertebrates, suggesting that modifications adapting to the respective living conditions or respiratory organs have taken place effectively near the amino acid residues essential for the manifestation of cooperative oxygen binding. (4) The amino acid residues at other sites are changed from one to another species even within the same class, showing a constant substitution rate as a whole. These amino acid substitutions may be nearly neutral, being under a weak functional constraint. The number of sites allowing such neutral substitutions is rather small, less than one-half of all the sites in the adult hemoglobins of bird and mammal, whereas it amounts to two-thirds in teleost fish hemoglobins.

Amino Acid Sequence↗
PubMed1998

Plant NADP-dependent isocitrate dehydrogenases are predominantly localized in the cytosol.

The isoenzyme patterns of NADP-isocitrate dehydrogenase (NADP-IDH; EC 1.1.1.42) have been investigated in 15 species of higher plants using dietylaminoethyl ion-exchange chromatography and immunological techniques. The obtained results unambiguously demonstrate that the cytosolic enzyme is the predominant form in leaf extracts of all the surveyed plant species. The chloroplastic isoenzyme, previously reported in pea (Pisum sativum L.) leaves (R.D. Chen et al., 1989, Planta 178; 157-163), is a minor form in ferns and dicotyledonous angiosperms and is undetectable in gymnosperms and monocotyledonous angiosperms. Comparison of immunological relatedness suggests that the proteins of cytosolic isoenzymes have been highly conserved in the course of plant evolution. The data support the previously proposed idea that the cytosol is the major site for alpha-ketoglutarate production to be used for nitrogen assimilation.

Cytosol↗
PubMed2002

Diagnostic mini-video assisted thoracic surgery. Effectiveness and accuracy of new generation 2.0 mm instruments.

OBJECTIVE: Recently 2.0 mm mini-VATS has aroused much interest among surgeons involved with endoscopic surgery. We report our initial experience with the first first 54 patients who underwent this procedure. The aim of this study is to evaluate the effectiveness and accuracy of mini-VATS. METHODS: 54 patients were undertaken to mini-VATS for diagnostic purposes. Patients were randomly selected and the indication for operation was set by the classic VATS criteria. 35 (65%) patients were treated under general anesthesia, while 19 (35%) patients were treated under local anesthesia. RESULTS: The average length of hospital stay was 1.8 +/- 0.9 days. The days of requirement for narcotic analgesia were 1.9 +/- 1.0. Diagnostic accuracy was 100%; morbidity and mortality rates were 0%. CONCLUSIONS: The high diagnostic accuracy and low operative danger, combined with less postoperative pain, due to minor surgical trauma and faster patient recovery, has established mini-VATS as a dynamic competitor to the classic VATS procedure. Since high technology is a strong partner in endoscopic surgery, a strong potentiality for evolution exists.

Adult↗
PubMed1991

Host-associated selection of sequence variants from a satellite RNA of cucumber mosaic virus.

The sequence of lx-satRNA, a CMV-satRNA necrogenic for tomato that shows the unusual property of accumulating in cucumber and in squash to levels similar to those in tomato and in tobacco, was determined. When compared with the sequences of other necrogenic CMV-satRNAs that do not show this property, or with a sequence variant of lx-satRNA that retains it, the high accumulation of lx-satRNA in squash was correlated with the presence of two U/C transitions. The sequences of progeny lx-satRNA from passage experiments in tomato and in squash show that a sequence variant having a U at position 102 was selected in tomato and that the parent sequence with a C at 102 was consistently restored in squash when this U-variant was used as inoculum. The results from these passage experiments may be explained by the heterogeneous nature of RNA populations, built from a number of variants of a master sequence, and illustrate the validity of this concept for CMV-satRNAs. The data also show that a minor sequence change, such as the transition C/U at 102, may have a major effect on the fitness of sequence variants of CMV-satRNAs in different hosts, and this may be relevant to the evolution in nature of these small RNAs.

Base Sequence↗
PubMed1996

Magnetic transcranial stimulation in acute stroke: early excitation threshold and functional prognosis.

Magnetic transcranial stimulation was used in 90 subjects (60 acute ischaemic sylvian strokes and 30 healthy controls) in order to evaluate the clinical value of the excitation threshold (ET) in the estimation of functional prognosis. ET mean values recorded 7, 30 and 90 days after stroke (at D7, D30 and D90) in two distal muscles of the upper limbs of the patients were compared with results obtained in 30 healthy control subjects. The data from the patients who ultimately achieved a satisfactory functional recovery at D90 were compared with those from patients who had not recovered in that time. Our results suggest that ET evolution differs according to functional outcome: (1) ET mean values were increased in the stroke patients at D7, but ET was constantly lower at D30 and D90 in patients who recovered than in those who did not. (2) ET temporal evolution showed a gradual decrease of the mean values from D7 to D90 in both stroke groups. This ET decrease was more marked in the patients who recovered from D30 to D90, but with only minor change after D30. (3) The localisation of the lesion had no significant effect on ET mean values at D7, D30 or D90. We conclude that the predictive value of ET estimation might be utilised at D30 in patients with ischaemic sylvian strokes.

Adult↗
PubMed2002

The palm subdomain-based active site is internally permuted in viral RNA-dependent RNA polymerases of an ancient lineage.

Template-dependent polynucleotide synthesis is catalyzed by enzymes whose core component includes a ubiquitous alphabeta palm subdomain comprising A, B and C sequence motifs crucial for catalysis. Due to its unique, universal conservation in all RNA viruses, the palm subdomain of RNA-dependent RNA polymerases (RdRps) is widely used for evolutionary and taxonomic inferences. We report here the results of elaborated computer-assisted analysis of newly sequenced replicases from Thosea asigna virus (TaV) and the closely related Euprosterna elaeasa virus (EeV), insect-specific ssRNA+ viruses, which revise a capsid-based classification of these viruses with tetraviruses, an Alphavirus-like family. The replicases of TaV and EeV do not have characteristic methyltransferase and helicase domains, and include a putative RdRp with a unique C-A-B motif arrangement in the palm subdomain that is also found in two dsRNA birnaviruses. This circular motif rearrangement is a result of migration of approximately 22 amino acid (aa) residues encompassing motif C between two internal positions, separated by approximately 110 aa, in a conserved region of approximately 550 aa. Protein modeling shows that the canonical palm subdomain architecture of poliovirus (ssRNA+) RdRp could accommodate the identified sequence permutation through changes in backbone connectivity of the major structural elements in three loop regions underlying the active site. This permutation transforms the ferredoxin-like beta1alphaAbeta2beta3alphaBbeta4 fold of the palm subdomain into the beta2beta3beta1alphaAalphaBbeta4 structure and brings beta-strands carrying two principal catalytic Asp residues into sequential proximity such that unique structural properties and, ultimately, unique functionality of the permuted RdRps may result. The permuted enzymes show unprecedented interclass sequence conservation between RdRps of true ssRNA+ and dsRNA viruses and form a minor, deeply separated cluster in the RdRp tree, implying that other, as yet unidentified, viruses may employ this type of RdRp. The structural diversification of the palm subdomain might be a major event in the evolution of template-dependent polynucleotide polymerases in the RNA-protein world.

Amino Acid Motifs↗
PubMed2005

Chronic asymptomatic contralateral wrist scapholunate dissociation.

BACKGROUND: The authors report a series of six patients who presented with scapholunate dissociation, with no significant contralateral antecedent trauma and no rheumatoid arthritis or congenital ligamentous laxity. Such patients may present with pain or a snapping/popping sensation in one wrist, undergo radiographs of both wrists, and are discovered to have scapholunate gapping bilaterally. The literature contains few reports of this condition, and this series of six is a relatively large one for this infrequently reported condition. METHODS: The six charts were reviewed retrospectively; each patient was asked to return for follow-up and radiographic examination and each participated in a telephone questionnaire about pain, activity changes, new treatments, and exacerbation of wrist problems. The average follow-up was 39 months, with a range of 6 months to 13.5 years. RESULTS: One patient with severe unilateral instability and persistent pain underwent soft-tissue surgical repair (Blatt reconstruction); another demonstrated unilateral dorsal intercalated segment instability with moderate pain symptoms but declined surgical reconstruction. The other 10 wrists, despite radiographically demonstrated widened scapholunate angles and rotatory subluxation of the scaphoid, had mild or no pain and no dorsal intercalated segment instability deformity. CONCLUSIONS: The evolution of the bilateral form of scapholunate dissociation seems to be benign unless dorsal intercalated segment instability deformity is present, which may then rapidly progress to degenerative arthritis and scapholunate advanced collapse wrist. Severe or minor repetitive trauma, inflammation, infection, tumors, and congenital ligamentous laxity have been etiologically implicated in scapholunate dissociation. The natural history of scapholunate dissociation involves volar rotation of the scaphoid and dorsal rotation of the lunate, progressing to malalignment and eventual arthrosis between the scaphoid and radius, the capitate and lunate, and the lunate and hamate bones.

Adult↗
PubMedDate not supplied

Treatable partial epilepsy and unilateral opercular neuronal migration disorder.

Five patients with treatable partial epilepsy and unilateral opercular neuronal migration disorder (NMD) are reported. Outcome was considered favorable when seizure control was prompt and complete with appropriate antiepileptic drug (AED) therapy, and when there was no relapse after AED discontinuation. Minor cortical sensorimotor defects were noted in 4 patients. All had normal mental status. No epileptic discharges were observed in the EEG of 4 patients, but rolandic spikes were observed in 1. The electroclinical and evolutive features suggested partial idiopathic epilepsy in 2 patients. Cases with focal neuronal migration disorders and favorable epilepsy outcome are probably more common than has been reported previously. The extent and location of the underlying microscopic lesions associated with the radiologically detectable cortical dysplasia may influence clinical outcome.

Adolescent↗
PubMed1982

Trisomy 15 and other nonrandom chromosome changes in Rauscher murine leukemia virus-induced leukemia cell lines.

The cytogenetics of Rauscher murine leukemia virus-induced erythroid, myeloid, and lymphatic leukemias were studied in BALB/c and DBA/2 mice. In primary virus-induced leukemias, no chromosome abnormalities were found. However, in tumors derived from transplanted leukemia tissue and in cell lines obtained from these tumors, euploidy and mostly aneuploidy were observed that varied according to the type of tumor cells and the number of passages. Eleven erythroleukemia cell lines showed aneuploidy from the first in vivo transplant stage on. Nonrandom abnormalities were found: trisomy 15 in 9 of 11 lines, followed by trisomy 3 in 8 of 11 lines and monosomy 6 in 5 of 11 lines. Subsequent evolution of the karyotypes was frequent (10 of 11 lines) and rapid. In vivo cell lines established from these tumors showed many structural rearrangements. Three myeloid lines revealed a stable karyotype with no or only minor changes: trisomy 15 in 1 line and normal diploid in 2 lines. One lymphatic leukemia cell line established in vitro presented with a very stable karyotype: trisomies 14 and 15. Another in vivo transplantable line showed trisomies 11, 9, and 17. These results suggest that trisomy of chromosome 15 plays a significant role in tumors derived from different types of mouse leukemias.

Aneuploidy↗