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PubMed1979

Evolution of the differential regulation of duplicate genes after polyploidization.

In the 50 million years since the polyploidization event that gave rise to the catostomid family of fishes the duplicate genes encoding isozymes have undergone different fates. Ample opportunity has been available for regulatory evolution of these duplicate genes. Approximately half the duplicate genes have lost their expressions during this time. Of the duplicate genes remaining, the majority have diverged to different extents in their expression within and among adult tissues. The pattern of divergence of duplicate gene expression is consistent with the accumulation of mutations at regulatory genes. The absence of a correlation of extent of divergence of gene expression with the level of genetic variability for isozymes at these loci is consistent with the view that the rates of regulatory gene and structural gene evolution are uncoupled. The magnitude of divergence of duplicate gene expressions varies among tissues, enzymes, and species. Little correlation was found with the extent of divergence of duplicate gene expression within a species and its degree of morphological "conservatism", although species pairs which are increasingly taxonomically distant are less likely to share specific patterns of differential gene expression. Probable phylogenetic times of origin of several patterns of differential gene expression have been proposed. Some patterns of differential gene expression have evolved in recent evolutionary times and are specific to one or a few species, whereas at least one pattern of differential gene expression is present in nearly all species and probably arose soon after the polyploidization event. Multilocus isozymes, formed by polyploidization, provide a useful model system for studying the forces responsible for the maintenance of duplicate genes and the evolution of these once identical genes to new spatially and temporally specific patterns of regulation.

Animals↗
PubMed1978

Ribosomal RNA homologies and the evolution of the filamentous blue-green bacteria.

Ribosomal RNA (rRNA) sequence homology (as determined by comparisons of T1 oligonucleotide catalogs of 32P-labeled 16S rRNAs) has been used to assess phylogenetic relationships within the filamentous and unicellular blue-green bacteria, and to identify regions of evolutionary conservatism within blue-green bacterial 16S rRNAs. Nostoc and Fishcherella, representatives of two morphologically distinct and highly differentiated orders, are shown to be as closely related (on the basis of RNA sequence homology) as typical members of the non-blue-green bacterial genus Bacillus. They are further shown to be (on the same basis) indistinguishable from typical unicellular members of a subgroup of the unicellular blue-green bacterial order Chroococcales. These results have general implications for studies of the origin of differentiated prokaryotes and of evolutionary change in prokaryotic macromolecules. In particular, they provide indirect evidence that the divergences of contemporary major prokaryotic groups are truly ancient ones.

Base Sequence↗
PubMed1993

Results of surgery for malignant bowel obstruction in advanced, unresectable, recurrent colorectal cancer.

When conservative treatment fails in the management of patients with malignant bowel obstruction secondary to advanced, recurrent colorectal cancer, the attitude toward surgery is often less than enthusiastic because of the limited life expectancy. We report a retrospective review of 30 patients with unresectable intra-abdominal disease who underwent laparotomy for the relief of bowel obstruction. Normal bowel function was restored in 19 patients (63 percent). The failures included five patients (17 percent) who died as a result of surgical complications and six patients (20 percent) who despite the surgery had continuing obstruction. Postoperative complications occurred in eight patients (27 percent). The median survival was significantly improved in those who benefited from the operation (192 days vs. 26 days; P = 0.0001). Whether the obstruction occurred at one site or more than one site appeared not to influence the outcome of surgery. Obstruction recurred after a mean symptom-free interval of 120 days in eight of those relieved by the initial operation. Half of these patients responded to conservative treatment, and surgery was again beneficial in three of the remaining four. Our results justify a more positive approach toward this problem, and, when conservatism fails, laparotomy should be undertaken in those who are not terminally ill.

Adult↗
PubMed1995

Stapled stricturoplasty for Crohn's disease. A new technique.

PURPOSE: Stricturoplasty was originally used to treat multiple fibrotic strictures of tuberculosis. As the pendulum of treatment of Crohn's disease swung toward conservatism and bowel preservation, stricturoplasty was performed in Crohn's disease. Stricturoplasty can be used when there is limited, well-localized disease and should be avoided in the presence of grossly inflamed or infected material. We describe a new technique of stricturoplasty. METHODS: Typically stricturoplasty is performed in a manner similar to a Heineke-Mikulicz pyloroplasty. A stapled stricturoplasty technique has been previously described, but in actuality these are more similar to a bypass procedure. Our technique uses a stapled, open technique similar to the triangulating method of bowel anastomosis. This was performed in one patient to correct six strictures. RESULTS: Our patient did well postoperatively and developed no significant complications. He has no evidence of recurrent strictures. CONCLUSION: We describe a stapled stricturoplasty technique that is truly a stricturoplasty because the bowel lumen is increased; it is similar to the triangulating method of end-to-end stapled bowel anastomosis. It is safe, efficient, and effective. Additionally, it allows radiographic location of the stricturoplasty site, thus allowing determination of effectiveness of the procedure as well as recurrence.

Constriction, Pathologic↗
PubMed1987

Ubiquitin genes as a paradigm of concerted evolution of tandem repeats.

Ubiquitin is remarkable for its ubiquitous distribution and its extreme protein sequence conservation. Ubiquitin genes comprise direct repeats of the ubiquitin coding unit with no spacers. The nucleotide sequences of several ubiquitin repeats from each of humans, chicken, Xenopus, Drosophila, barley, and yeast have recently been determined. By analysis of these data we show that ubiquitin is evolving more slowly than any other known protein, and that this (together with its gene organization) contributes to an ideal situation for the occurrence of concerted evolution of tandem repeats. By contrast, there is little evidence of between-cluster concerted evolution. We deduce that in ubiquitin genes, concerted evolution involves both unequal crossover and gene conversion, and that the average time since two repeated units within the polyubiquitin locus most recently shared a common ancestor is approximately 38 million years (Myr) in mammals, but perhaps only 11 Myr in Drosophila. The extreme conservatism of ubiquitin evolution also allows the inference that certain synonymous serine codons differing at the first two positions were probably mutated at single steps.

Animals↗
PubMed1995

Personality and the inheritance of smoking behavior: a genetic perspective.

In contrast to the extensive research effort to understand the genetic contribution to alcoholism risk, there has been little research directed at understanding genetic influences on smoking behavior. Data from large twin studies in Scandinavia and Australia are consistent with a major genetic influence on the probability that an individual will become a smoker ("initiation") and will persist in the smoking habit once smoking has started ("persistence"). We use data from the 1988/1989 follow-up survey of the Australian NH&MRC twin panel to determine to what degree personality measures (Tridimensional Personality Questionnaire, Eysenck Personality Questionnaire--Revised) and attitudinal and sociodemographic variables (social and political conservatism, education, religious involvement) might account for genetic or environmental influences on smoking. While we find significant phenotypic associations between these variables and smoking, these are too modest to account for much of the genetic variance. Possible mechanisms by which this genetic variance may arise are discussed.

Adolescent↗
PubMed1998

German women in chemistry, 1895-1925 (Part I).

The paper traces the entrance of German women into the chemistry profession from the 1890s to 1925, examining how they first overcame social and cultural conservatism to obtain access to opportunities for a chemical education during the later Kaiserreich, then began to seek academic and industrial careers and to establish a professional organization in the face of resistance from the established Verein Deutscher Chemiker. The paper examines the effect of World War I and the advent of the Weimar Republic in completing the process whereby German women achieved a small but significant role in the profession of chemistry, in science as well as industry. Finally, it discusses the considerable limitations on women's full and equal participation that still remained by 1925.

Chemistry↗
PubMed1998

The angiogenins.

The angiogenic and other biological functions of the angiogenins, members of the pancreatic RNase superfamily of proteins, are reviewed in the context of their primary and tertiary structures. The ribonucleolytic activity and interactions with the placental ribonuclease inhibitor have seen much study in the last few years. The mechanism of the angiogenic activity of angiogenin has recently been postulated as involving multiple interactions with other proteins through specific regions on the molecular surface of angiogenin. These molecular partners include heparin, plasminogen, elastase, angiostatin, actin and most importantly a 170-kilodalton receptor on subconfluent endothelial cells. The existence of the latter receptor was established in conjunction with a mitogenic activity of angiogenin on subconfluent cells. The levels of angiogenin in various physiological and disease states are summarized, including various studies on pregnancy and angiogenin. Correlations are seen between states of enhanced angiogenesis and angiogenin levels. An overview of the relationship of angiogenin and the other RNases of the superfamily showed that their genes all are in relative close proximity on human chromosome 14. Examination of the many expressed sequence tags published in the public databanks, for angiogenin and the other RNases, revealed that angiogenin and RNase-4 (the most evolutionarily conserved RNase), share various identical 5'-untranslated regions on their sets of messenger RNAs, suggesting that their genes are in very close proximity on chromosome 14 and that they are products of differential splicing. This in turn suggests that, in both humans and mice, expression of these two proteins is under identical control, with obvious implications for their biological activities. The evolutionary history of the angiogenins is examined briefly on the basis of the protein sequences of the human, rabbit, pig, two bovine and four mouse angiogenins, and two mouse angiogenin pseudogene sequences. The discrepancy between the conventional requirement for conservatism in structure to allow multimolecule interactions, and the actual fast-changing sequence of the angiogenins, in concert with the wide-ranging activity even in birds, of human angiogenin, is discussed.

Amino Acid Sequence↗
PubMed2002

Comparative analysis of chloroplast DNA in Pyrus species: physical map and gene localization.

A physical map of chloroplast DNA (cpDNA) of pear [Pyrus ussuriensis var. hondoensis (Nakai et Kikuchi) Rehder] was constructed using five restriction enzymes, SalI, XhoI, BamHI, SacI and PstI. This information will make it possible to investigate the phylogenetic relationships between Pyrus species. Pear cpDNA was found to be a circular molecule with a total size of about 156 kb in which two inverted repeats of 24.8 kb divide the molecule into small (17 kb) and large (90 kb) single-copy regions. The endonuclease recognition sites in the physical map were determined by single and double digestion of 13 lambda phage clones which covered the entire sequence of the pear cpDNA. Twenty nine genes were localized on the physical map of the pear cpDNA. The structure of pear cpDNA was almost the same in terms of genome size and gene order as that of tobacco cpDNA. RFLP analysis was carried out on cpDNAs from five Pyrus species (Pyrus pyrifolia, Pyrus ussuriensis, Pyrus calleryana, Pyrus elaeagrifolia and Pyrus communis). Two mutations, a recognition-site mutation and a length mutation (deletion), were found only in the cpDNA of P. pyrifolia cultivars. These mutations were localized on the physical map of pear cpDNA. The number of mutations of cpDNA in Pyrus species are small in comparison with those of other angiosperms, suggesting a high degree of genome conservatism in Pyrus species.

Chloroplasts↗
PubMed2003

From swimming to walking: a single basic network for two different behaviors.

In this paper we consider the hypothesis that the spinal locomotor network controlling trunk movements has remained essentially unchanged during the evolutionary transition from aquatic to terrestrial locomotion. The wider repertoire of axial motor patterns expressed by amphibians would then be explained by the influence from separate limb pattern generators, added during this evolution. This study is based on EMG data recorded in vivo from epaxial musculature in the newt Pleurodeles waltl during unrestrained swimming and walking, and on a simplified model of the lamprey spinal pattern generator for swimming. Using computer simulations, we have examined the output generated by the lamprey model network for different input drives. Two distinct inputs were identified which reproduced the main features of the swimming and walking motor patterns in the newt. The swimming pattern is generated when the network receives tonic excitation with local intensity gradients near the neck and girdle regions. To produce the walking pattern, the network must receive (in addition to a tonic excitation at the girdles) a phasic drive which is out of phase in the neck and tail regions in relation to the middle part of the body. To fit the symmetry of the walking pattern, however, the intersegmental connectivity of the network had to be modified by reversing the direction of the crossed inhibitory pathways in the rostral part of the spinal cord. This study suggests that the input drive required for the generation of the distinct walking pattern could, at least partly, be attributed to mechanosensory feedback received by the network directly from the intraspinal stretch-receptor system. Indeed, the input drive required resembles the pattern of activity of stretch receptors sensing the lateral bending of the trunk, as expressed during walking in urodeles. Moreover, our results indicate that a nonuniform distribution of these stretch receptors along the trunk can explain the discontinuities exhibited in the swimming pattern of the newt. Thus, separate limb pattern generators can influence the original network controlling axial movements not only through a direct coupling at the central level but also via a mechanical coupling between trunk and limbs, which in turn influences the sensory signals sent back to the network. Taken together, our findings support the hypothesis of a phylogenetic conservatism of the spinal locomotor networks generating axial motor patterns from agnathans to amphibians.

Animals↗
PubMed2006

Hox gene expression in larval development of the polychaetes Nereis virens and Platynereis dumerilii (Annelida, Lophotrochozoa).

The bilaterian animals are divided into three great branches: the Deuterostomia, Ecdysozoa, and Lophotrochozoa. The evolution of developmental mechanisms is less studied in the Lophotrochozoa than in the other two clades. We have studied the expression of Hox genes during larval development of two lophotrochozoans, the polychaete annelids Nereis virens and Platynereis dumerilii. As reported previously, the Hox cluster of N. virens consists of at least 11 genes (de Rosa R, Grenier JK, Andreeva T, Cook CE, Adoutte A, Akam M, Carroll SB, Balavoine G, Nature, 399:772-776, 1999; Andreeva TF, Cook C, Korchagina NM, Akam M, Dondua AK, Ontogenez 32:225-233, 2001); we have also cloned nine Hox genes of P. dumerilii. Hox genes are mainly expressed in the descendants of the 2d blastomere, which form the integument of segments, ventral neural ganglia, pre-pygidial growth zone, and the pygidial lobe. Patterns of expression are similar for orthologous genes of both nereids. In Nereis, Hox2, and Hox3 are activated before the blastopore closure, while Hox1 and Hox4 are activated just after this. Hox5 and Post2 are first active during the metatrochophore stage, and Hox7, Lox4, and Lox2 at the late nectochaete stage only. During larval stages, Hox genes are expressed in staggered domains in the developing segments and pygidial lobe. The pattern of expression of Hox cluster genes suggests their involvement in the vectorial regionalization of the larval body along the antero-posterior axis. Hox gene expression in nereids conforms to the canonical patterns postulated for the two other evolutionary branches of the Bilateria, the Ecdysozoa and the Deuterostomia, thus supporting the evolutionary conservatism of the function of Hox genes in development.

Animals↗
PubMed2005

Parasite species coexistence and limiting similarity: a multiscale look at phylogenetic, functional and reproductive distances.

The factors that control biodiversity have been the focus of numerous recent investigations; these include species interactions, speciation, environmental gradients and heterogeneity, all of these operating differently at each observation scale. We used a null model to examine the influence of two forces shaping the community structure of Dactylogyrus species parasitic on roach (Rutilus rutilus) gills: interspecific competition that might prevent the coexistence of the most similar species and environmental filters that might result in the most similar species coexisting together. The study was carried out on two sets of fish from two different localities in the Morava river basin (Czech Republic) to evaluate the consistency of the results across host populations, and at three different scales of observation to test for the scale dependence of assembly rules. In decreasing order, from largest to smallest, the three spatial scales investigated were: the individual fish, the individual gill arch and individual sections of each gill arch. The similarity between pairs of parasite species was measured using three different criteria: (1) phylogeny, (2) quantitative functional traits consisting of parasite size and morphometric measurements of the attachment organ's sclerotized parts and (3) qualitative attributes of reproductive organs. First, our study reveals a strong conservatism of ecological characters for the nine Dactylogyrus parasite species, in particular regarding the attributes of their copulatory organs. Second, our study did not find any limitation of similarity among coexisting Dactylogyrus species due to interspecific competition, irrespective of the scale and the similarity measures considered. Conversely, our results support the niche filtering hypothesis, preventing the co-occurrence of species too dissimilar from one another. This process is particularly apparent at the scale of the individual fish and for functional traits associated with the hard parts of the parasites' attachment organs. In both localities, the Dactylogyrus species that occur on the same fish individuals tend to have similar values for the haptor dimensions. Our study supports previous studies on monogenean parasite communities indicating a weak influence of competition as a structuring force, but it goes a step further by identifying environmental filtering as a key process shaping these communities.

Animals↗
PubMed2006

Dietary specialization in European species groups of seed beetles (Coleoptera: Bruchidae: Bruchinae).

Because of their particular biology, seed beetles exhibit a strong relationship with their larval host plants. In Europe, however, field data have long been scarce and unreliable. The results of Legume seed collections of nearly 1,000 samples belonging to 292 species from various locations in Europe are summarized. The status of current Bruchidius species groups is amended on morphological and phylogenetic bases. Recent advances in the knowledge of phylogenetic structures of both Fabaceae and Bruchinae provide a new picture of Bruchinae-Fabaceae interactions. It reveals a certain level of host conservatism. The hypothesis of radiative adaptation seems the most compatible with observed data.

Adaptation, Physiological↗
PubMed2005

Response to novel housing in two groups of captive tufted capuchin monkeys (Cebus apella).

The influence of age, maternal status, and the presence of a group male on use of space was assessed in two groups of captive tufted capuchin monkeys that underwent a move from indoor housing to a larger outdoor facility. Both groups originally contained two adult males, but only one group retained a male after the move. Following the move, mothers spent less time on the ground when carrying their infants than they did when not carrying their infants. In the group with no male (1) individuals decreased time spent on the ground relative to pre-move levels, whereas no such difference was noted in the group with the male; (2) females spent more time carrying their infants than did females in the group with a male. In the group with the adult male, juveniles spent less time on the ground than did non-mother adult females, whereas no difference had existed prior to the move. Grooming rates dropped from pre-move to post-move, but the mean number of partners with which each animal was in contact increased. Measures of social behavior varied across post-move observation periods inversely to time spent on the ground. These results are consistent with the view that an individual's relative vulnerability influences behavioral conservatism in novel environments, and suggests a relatively profound role for males in promoting exploration of new space in this species.

Age Factors↗
PubMed2006

Multiple nucleolus organizer regions in Leptodactylus mystacinus (Amphibia, Anura) and comments on its systematic position in the L. fuscus group based on cytogenetic and molecular analyses.

Specimens of Leptodactylus mystacinus from Brazil were karyotyped with conventional and differential staining. The 2n = 22 karyotype is similar to that found for the majority of the Leptodactylus, the karyotypic conservatism also confirmed by the similarity of the replication banding patterns with those previously described. L. mystacinus has a small amount of C-banded heterochromatin, located mainly at the centromeres, although telomeric or interstitial bands have also been noticed. With DA/CMA(3) some chromosome regions showed slightly bright fluorescence, and with DA/DAPI, no particular AT-rich repetitive region was observed. Silver staining showed an extensive inter- and intraindividual variation in the number and position of Ag-positive regions, in 1p, 4p, 8p, 8q, and 11p. Nevertheless, FISH using rDNA probes confirmed only the signals on the short arms of chromosomes 4 and 8 as true NORs. The remaining silver stained regions are probably due to the heterochromatin with some affinity to the Ag-staining. Phylogenetic analysis based on partial cytochrome b sequence revealed that L. mystacinus forms a basal branch, so that the presence of multiple NORs in pairs 4 and 8 in this species indicates an autapomorphy.

Animals↗
PubMed2006

Symbolic racism and Whites' attitudes towards punitive and preventive crime policies.

This study analyzes the determinants of Whites' support for punitive and preventive crime policies. It focuses on the predictive power of beliefs about race as described by symbolic racism theory. A dataset with 849 White respondents from three waves of the Los Angeles County Social Survey was used. In order to assess the weight of racial factors in crime policy attitudes, the effects of a range of race-neutral attitude determinants were controlled for, namely individual and structural crime attributions, perceived seriousness of crime, crime victimization, conservatism and news exposure. Results show a strong effect of symbolic racism on both types of crime policies, and in particular on punitive policies. High levels of symbolic racism are associated with support for tough, punitive crime policies and with opposition to preventive policies. Sub-dimensions of symbolic racism qualified these relationships, by showing that internal symbolic racism (assessing perceived individual deficiencies of Blacks) was most strongly predictive of punitiveness, whereas external symbolic racism (denial of institutional discrimination) predicted opposition to structural remedies. On the whole, despite the effects of race-neutral factors, the impact of symbolic racism on policy attitudes was substantial. Thus, White public opinion on both punitive and preventive crime policies is at least partially driven by racial prejudice.

Adolescent↗
PubMed2002

Peer review and innovation.

Two important aspects of the relationship between peer review and innovation includes the acceptance of articles for publication in journals and the assessment of applications for grants for the funding of research work. While there are well-known examples of the rejection by journals of first choice of many papers that have radically changed the way we think about the world outside ourselves, such papers do get published eventually, however tortuous the process required. With grant applications the situation differs in that the refusal of a grant necessarily curtails the possible research that may be attempted. Here there are many reasons for conservatism and reservation as to the ability of a grant allocation process based on peer review to deliver truly innovative investigations. Other methods are needed; although such methods need not be applied across the board, they should constitute the methods whereby some 10-20% of the grant monies are assigned. The nomination of prizes for specific accomplishments is one way of achieving innovation although this presumes that investigators or institution already have available the money necessary to effect the innovations; otherwise it is a question of the selection and funding of particular individuals or institutions and requiring them to solve particular problems that are set in the broadest of terms.

Diffusion of Innovation↗
PubMed1978

Mitral valve repair for significant mitral insufficiency.

There has been skepticism since the early days of open heart surgery that good long-term or even short-term results were possible with repair of pure mitral insufficiency. The authors report 145 patients in whom a markedly insufficient mitral valve was repaired 6 months to 17 years previously and another 55 patients in whom repair of the insufficient mitral valve was performed along with myocardial revascularization from 6 months to 7 years previously. Comparative data with other published work reveals superior results with repair than with replacement with Starr-Edwards and Hancock glutaraldehyde-treated porcine valves and with far less emboli. Conservatism is urged in operating upon patients with mitral insufficiency. Repair of the valve rather than replacement is stressed for those patients requiring surgery.

Adult↗