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PubMed2002

Sexually antagonistic coevolution in a mating system: combining experimental and comparative approaches to address evolutionary processes.

We combined experimental and comparative techniques to study the evolution of mating behaviors within in a clade of 15 water striders (Gerris spp.). Superfluous multiple mating is costly to females in this group, and consequently there is overt conflict between the sexes over mating. Two alternative hypotheses that could generate interspecific variation in mating behaviors are tested: interspecific variation in optimal female mating rate versus sexually antagonistic coevolution of persistence and resistance traits. These potentially coevolving traits include male grasping and female antigrasping structures that further the interests of one sex over the other during premating struggles. Both processes are known to play a role in observed behavioral variation within species. We used two large sets of experiments to quantify behavioral differences among species, as well as their response to an environmentally (sex-ratio) induced change in optimal female mating rate. Our analysis revealed a large degree of continuous interspecific variation in all 20 quantified behavioral variables. Nevertheless, species shared the same set of behaviors, and each responded in a qualitatively similar fashion to sex-ratio alterations. A remarkably large proportion (> 50%) of all interspecific variation in the magnitude of behaviors, including their response to sex ratio, could be captured by a single multivariate axis. These data suggest tight coevolution of behaviors within a shared mating system. The pattern of correlated evolution was best accounted for by antagonistic coevolution in the relative abilities of each sex to control the outcome of premating struggles. In species where males have a relative advantage, mating activity is high, and the opposite is found in species where females have gained a relative advantage. Our analyses also suggested that evolution has been unconstrained by history, with no consistent evolutionary tendency toward or away from male or female relative advantage.

Analysis of Variance↗

PubMed1992

Studies on the structure and function of the N-terminal domain of the pneumococcal murein hydrolases.

The structures of the choline-dependent pneumococcal murein hydrolases, LYTA amidase and CPL1 lysozyme, and the choline-independent CPL7 lysozyme were analysed by controlled proteolytic digestions. The trypsin cleavage of the CPL1 and CPL7 lysozymes produced two resistant polypeptides, F1 and F7 respectively, corresponding to the N-terminal domain of the enzymes, whereas the amidase LYTA was completely hydrolysed by the protease. Interestingly, the F1 and F7 fragments showed a low, but significant, choline-independent lysozyme activity. Choline reduced the rate of proteolytic hydrolysis of choline-dependent enzymes, suggesting that the C-terminal choline-binding domain adopts a more resistant conformation in the presence of the ligand. On the other hand, the regions encoding the N-terminal domains of the three enzymes have been cloned and expressed in Escherichia coli, showing that these domains adopt an active conformation even in the absence of their C-terminal domains. The lower activity shown by the catalytic domains when compared with that of the complete enzymes suggests that the acquisition of a substrate-binding domain represents a noticeable evolutionary advantage for enzymes that interact with polymeric substrates, allowing them to achieve a higher catalytic efficiency. These results strongly reinforce the hypothesis that the pneumococcal murein hydrolases have been originated by fusion of two structural and functional independent domains, and provide new experimental support to the theory of modular evolution of proteins.

Amidohydrolases↗

PubMed1993

Interchange of functional domains switches enzyme specificity: construction of a chimeric pneumococcal-clostridial cell wall lytic enzyme.

Bacterial autolysins are endogenous enzymes that specifically cleave covalent bonds in the cell wall. These enzymes show both substrate and bond specificities. The former is related to their interaction with the insoluble substrate whereas the latter determine their site of action. The bond specificity allows their classification as muramidases (lysozymes), glucosaminidases, amidases, and endopeptidases. To demonstrate that the autolysin (LYC muramidase) of Clostridium acetobutylicum ATCC824 presents a domainal organization, a chimeric gene (clc) containing the regions coding for the catalytic domain of the LYC muramidase and the choline-binding domain of the pneumococcal phage CPL1 muramidase has been constructed by in vitro recombination of the corresponding gene fragments. This chimeric construction codes for a choline-binding protein (CLC) that has been purified using affinity chromatography on DEAE-cellulose. Several biochemical tests demonstrate that this rearrangement of domains has generated an enzyme with a choline-dependent muramidase activity on pneumococcal cell walls. Since the parental LYC muramidase was choline-independent and unable to degrade pneumococcal cell walls, the formation of this active chimeric enzyme by exchanging protein domains between two enzymes that specifically hydrolyse cell walls of bacteria belonging to different genera shows that a switch on substrate specificity has been achieved. The chimeric CLC muramidase behaved as an autolytic enzyme when it was adsorbed onto a live autolysin-defective mutant of Streptococcus pneumoniae. The construction described here provides experimental support for the theory of modular evolution which assumes that novel proteins have evolved by the assembly of preexisting polypeptide units.

Amino Acid Sequence↗

PubMed1998

Pathophysiology of Oestrus ovis infection in sheep and goats: a review.

Oestrus ovis is a very common parasite of sheep and goats in many countries. Its pathological effects are often underestimated because owners and veterinarians are used to seeing the infection. The study of natural and experimental infections has provided information about the evolution of the disease and its pathophysiology. Hypersensitivity is involved; the numbers of mast cells and eosinophils increase but changes in IgE have only recently been examined. Little is known about the development of immunity but it is possible that some animals are immunodeficient.

Animals↗

PubMed2004

Transient-state method for coupled evaluation of Soret and Fick coefficients, and related tortuosity factors, using free and porous packed thermodiffusion cells: application to CuSO4 aqueous solution ( 0.25M).

The measurement of Soret coefficients in liquids is not easy and usually not very precise because the resulting concentration gradient is small and moreover can be perturbed by undesired convection currents. In order to suppress, or to drastically reduce these convection currents, the use of a porous medium is sometimes suggested. The question arises as to whether the Soret coefficient is the same in free fluid and in porous medium. This is the aim of this paper. To this end, for a given liquid mixture, the time evolution of the vertical concentration gradient is experimentally measured in the same thermodiffusion cell filled first with the free liquid and next with a porous medium followed by saturation by the liquid mixture. Both the isothermal diffusion (Fick) coefficient and the Soret coefficient can be deduced, providing that a correct working equation is used. The proposed equation results from integration of the general mass conservation equation with realistic boundary conditions (zero mass flux at the boundaries) and some simplifying assumptions rendering this equation more tractable than the one proposed some decades ago by Bierlein (J.A. Bierlein, J. Chem. Phys. 23, 10 (1955)). The method is applied here to an electrolytic solution (CuSO4, 0.25 M) at a mean temperature of 37 degrees C. The Soret coefficients in free and porous medium (zircon microspheres in the range of 250-315 x 10(-6) m) may be considered to be equal ( S(T) = 13.2+/-0.5 x 10(-3) K(-1)) and the tortuosity factors for the packed medium are the same relative to thermodiffusion and Fick coefficients (tau = 1.51+/-0.02).

Journal Article↗

PubMed1977

Effect of succinimide on hyperoxaluria in the rat estimated value of the different dosing methods of oxaluria.

In the female rat intoxicated with ethylene glycol the oxaluria increases with the degree of intoxication. The increase is less in the animals treated with succinimide. The comparative study of the results of the dosages made with gas-liquid-chromatography and by various colorimetric methods show that this later gives varying results and underestimates high concentrations of oxalic acid. The result is that any study based on results of dosages of urinary oxalic acid made by colorimetry must be taken with some reserve, and this on whether the oxalic lithiasis is experimentally induced or human, or whether its evolution is spontaneous or influenced by a therapeutic.

Animals↗

PubMed1998

A glycine site antagonist, ZD9379, reduces number of spreading depressions and infarct size in rats with permanent middle cerebral artery occlusion.

BACKGROUND AND PURPOSE: Spreading depressions (SDs) occur in experimental focal ischemia and contribute to lesion evolution. N-Methyl-D-aspartate (NMDA) antagonists inhibit SDs and reduce infarct size. The glycine site on the NMDA receptor complex offers a therapeutic target for acute focal ischemia, potentially devoid of many side effects associated with competitive and noncompetitive NMDA antagonists. We evaluated the effect of the glycine antagonist ZD9379 on SDs and brain infarction. METHODS: Male Sprague-Dawley rats (n = 18) weighing 290 to 340 g undergoing permanent middle cerebral artery occlusion (MCAO) were randomly and blindly assigned to receive drug or placebo: group 1 (pre-MCAO treatment group; n=5), a 5-mg/kg bolus of ZD9379 over 5 minutes followed by 5 mg/kg per hour drug infusion for 4 hours beginning 30 minutes before MCAO; group 2 (post-MCAO treatment group; n=7), a 5-mg/kg bolus of ZD9379 30 minutes after MCAO followed by 5 mg/kg per hour drug infusion for 4 hours; and group 3 (control group; n=6), vehicle for 5 hours beginning 30 minutes before MCAO. SDs were monitored electrophysiologically for 4.5 hours after MCAO by continuous recording of cortical DC potentials and electrocorticogram. Infarct volume was measured 24 hours after MCAO by 2,3,5-triphenyltetrazolium chloride staining. RESULTS: Corrected infarct volume was 90+/-72 mm3 (mean+/-standard deviation) in group 1, 105+/-46 mm3 in group 2, and 226+/-40 mm3 in group 3 (P<.001). The corresponding numbers of SDs in the three groups were 8.2+/-5.8, 8.1+/-2.5, and 16.0+/-5.1, respectively (P<.01). When all animals (n=18) were analyzed, infarct volumes and the number of SDs were significantly correlated (r=.68, P=.002). CONCLUSIONS: This study demonstrated that ZD9379 initiated before or after MCAO significantly reduced the number of SDs and infarct volume in a permanent focal ischemia model, implying that ZD9379 is neuroprotective and its neuroprotective effect may be related to inhibiting ischemia-related SDs.

Analysis of Variance↗

PubMed2006

Genetic Parallel Programming: design and implementation.

This paper presents a novel Genetic Parallel Programming (GPP) paradigm for evolving parallel programs running on a Multi-Arithmetic-Logic-Unit (Multi-ALU) Processor (MAP). The MAP is a Multiple Instruction-streams, Multiple Data-streams (MIMD), general-purpose register machine that can be implemented on modern Very Large-Scale Integrated Circuits (VLSIs) in order to evaluate genetic programs at high speed. For human programmers, writing parallel programs is more difficult than writing sequential programs. However, experimental results show that GPP evolves parallel programs with less computational effort than that of their sequential counterparts. It creates a new approach to evolving a feasible problem solution in parallel program form and then serializes it into a sequential program if required. The effectiveness and efficiency of GPP are investigated using a suite of 14 well-studied benchmark problems. Experimental results show that GPP speeds up evolution substantially.

Algorithms↗

PubMed2003

Ocular immune privilege: the eye takes a dim but practical view of immunity and inflammation.

The delicate visual axis that makes precise vision possible is highly vulnerable to the destructive potential of immunogenic inflammation. Immune privilege of the eye is the experimental expression of the way in which evolution has coped with the countermanding threats to vision of ocular infections and ocular immunity and inflammation. Ocular immune privilege has five primary features that account for its existence: blood:ocular barriers, absent lymphatic drainage pathways, soluble immunomodulatory factors in aqueous humor, immunomodulatory ligands on the surface of ocular parenchymal cells, and indigenous, tolerance-promoting antigen-presenting cells (APCs). Three manifestations of ocular immune privilege that have received the most extensive study are the intraocular microenvironment, which is selectively anti-inflammatory and immunosuppressive; the prolonged acceptance of solid tissue and tumor allografts in the anterior chamber; and the induction of systemic tolerance to eye-derived antigens. Anterior chamber-associated immune deviation is known to arise when indigenous, ocular APCs capture eye-derived antigens and deliver them to the spleen where multicellular clusters of these cells, natural killer T cells, marginal zone B cells, and gammadelta T cells create an antigen-presentation environment that leads to CD4(+) and CD8(+) alpha/beta T cells, which as regulators, suppress induction and expression of T helper cell type 1 (Th1) and Th2 immune expression systems. The ways the eye influences local and systemic immune responses to ocular antigens and pathogens carry risks to and benefits for mammalian organisms. As loss of sight is a powerful, negative-selecting force, the benefits of ocular immune privilege outweigh the risks.

Antigen-Presenting Cells↗

PubMed2004

Arrested development in Xenopus laevis tadpoles: how size constrains metamorphosis.

Xenopus laevis tadpoles that arrest development and remain as larvae for several years sometimes occur spontaneously in laboratory populations. These tadpoles cease development at an early hindlimb stage, but continue to grow and develop into grossly deformed giants. Giant tadpoles lack thyroid glands, and differ in morphology and behaviour from normal larvae. They are negatively buoyant, typically with small and partially solidified lungs, and have greatly enlarged fat bodies. Giant tadpoles have mature gonads with eggs and sperm, whereas normal tadpoles of the same stage have undifferentiated gonads. Larval reproduction has never been reported in anurans, but gonadal development decoupled from metamorphosis brings these giants the closest of any anurans to being truly neotenic. We discuss behavioural and morphological factors that may hinder both reproduction in giant Xenopus larvae and the evolution of neoteny in anurans in general. Experimental treatment with exogenous thyroid hormone induces some, but not complete, metamorphic changes in these giants. The limbs and head progress through metamorphosis; however, all tadpoles die at the stage when the tail would normally be resorbed. The disproportionate growth of tissues and organs in giant tadpoles may preclude complete metamorphosis, even under exogenous thyroid hormone induction.

Analysis of Variance↗

PubMed1996

Bleeding oesophageal varices.

BACKGROUND: The Danish contribution to evaluation and treatment of bleeding oesophageal varices. METHODS: Danish papers dealing with portal hypertension and oesophageal varices have been reviewed and set in relation to international publications. RESULTS: The Danish papers have mainly contributed with controlled clinical trials concerning both primary and secondary prophylaxis. Furthermore, they have dealt with pathophysiologic, clinical and experimental studies concerning portal haemodynamics and the evolution and treatment of variceal bleeding. CONCLUSION: The Danish studies have been well designed and are frequently cited. Further prospective randomized studies in the new treatment modalities are encouraged.

Denmark↗

PubMed1989

[Families in France and Sweden: the search for new models].

"Examination of the evolution of family models in France and Sweden reveals many similar trends: increase in the divorce rate, fall in marriage and fertility rates, decrease in the size of the average family, increase in the number of single parent families, diversity of rearranged households, etc. However, the authors stress the extent to which the historical and ideological context of this evolution is different in the two countries. Whereas new conjugal models are diffused rapidly in Sweden without provoking reactions of rejection, a certain ideology in France recommends an ideal of conjugal stability and demands a policy openly favouring an increased birth rate. The Swedes find contraception and abortion natural whereas they are still the subject of impassioned debates in France. The attitude to children is very different in the two countries. However, in both cases, although the evolution of family ties still has an experimental aspect it seems sufficiently radical to make it necessary to rethink the nature of social ties in general." (SUMMARY IN ENG)

Abortion, Induced↗

PubMedDate not supplied

[Muscular clearance after administration of phenoxybenzamine in shock].

The authors made an experimental investigation in the dog concerning the evolution of the muscular clearance of phenoxybenzamine in the course of de-shocking procedures. The animals were shocked by hemorrhage and were treated by perfusion of volemic mass and administration of phenoxybenzamine. This substance was flowed in paralell with the hemodynamic parameters and the rhythm of the diuresis. It was noted that the direction and the amplitude of changes concerning the half-life of Na131I do not depend on the blood pressure.

Animals↗

PubMedDate not supplied

[Genomic imprinting: a case of inherited hematocrit, radiosensitivity, and antioxidant status in human being, as well as weight of newborn mammals].

Epigenetic hypothesis of dynamic genomic parental imprinting, explaining the mechanisms of formation and inheritance of quantitative characters in multicellular organisms, is proposed. Method for analyzing the compliance of quantitative characters of organisms with the hypothesis of dynamic genomic parental imprinting is developed. Examples of human characters and characters of other mammals inherited in accordance with the proposed model are given. It is concluded that the hypothesis can be used for studying ontogeny and explaining the mechanisms of inheritance of the morphoses providing the stability and evolution of species. Possible ways of further experimental verification of the hypothesis and areas of its practical application are discussed.

Animals↗

PubMed1986

[Sequence of experimental remodeling of the mandibular periosteum in the rat].

The evolution of a synchronous bone remodeling sequence has been followed with time. This sequence was induced in the buccal mandibular cortex of the rat which undergoes modeling apposition after maxillary molar extractions. The sequence has been studied in the rat on day 0, 2, 4, 6, 8 and 12 after induction. Disappearance of the layer of osteoid tissue produced on day 0 was initially observed (day 2). The resorption phase reached a peak on day 4 and then decreased until day 12. The greatest inversion was observed on day 8 and then regressed. Apposition, completely absent on day 4, was again important on day 12. The variations with time of the 2 different osteoclast profiles, those in contact with bone (considered as active) and those at a distance from the bone surface (considered as inactive) allowed to study the kinetics of these cells. Whereas their total number was unchanged on day 4 and 6, on day 4 the active osteoclasts were more numerous: this situation was completely reversed on day 6. These facts suggest that the osteoclasts present were active for 1 to 2 days, then became inactive without change in number before their disappearance. This very reproducible model seems useful for understanding certain mechanisms occurring during bone remodeling and for testing the role of some mediators or pharmacological agents on the process.

Animals↗

PubMedDate not supplied

Mechanisms of lung tissue restructuration. A structural analysis of experimental and human materials.

Lung tissue restructuration is one of the most important components of chronic pneumopathies. Comparison of experimental and human data regarding the dynamic evolution of variously induced chronic lung processes pointed out as main mechanisms the bronchial and bronchiolar obstructions, the viral and fungal pneumonitic processes, the parenchymatous suppurative processes, the granulomatous organization of cellular reactions, the interlobular cell accumulations, the hypersensitivity reactions, and the lesions of small vessels. Mostly acting in association, these dynamic conditions determine the fibroplastic transformation of lesions, the exclusion of unventilated areas, the destruction of respiratory surfaces, the clear predominance of connective tissue structures, sometimes with ossifications; some microcavities persist within restructuring areas, sometimes delimited by alveolar or bronchiolar epithelia. The honeycomb lung is one of the evolutive possibilities of this restructuration of damaged tissues during chronic lung diseases.

Animals↗

PubMed1981

Experimental and clinical studies of mesenteric infarction.

Results of our experimental studies have demonstrated that, during the evolution of mesenteric infarction, lysosomal membrane instability occurs with the release of beta-N acetylhexosaminidase into the portal and systemic circulation. Preliminary clinical results suggest an elevation of the Hex B fraction in mesenteric infarction. Measurements of total and various fractions of beta-N acetylhexosaminidase in the blood may prove to be an early indication of necrosis of the intestine.

Adult↗

PubMed1982

[Anorexia nervosa. Presentation of two cases].

Two patients with anorexia nervosa were studied. One of them showed cerebral atrophy by computed tomography (CT) of the brain. This finding has been reported previously in three cases. No other reports have been found in Spanish literature. This data could be merely a CT finding. Etiopathogenic and therapeutic evolution is discussed. Behavior modification, based in experimental psychology was used in treatment. Hypercaloric and hyperproteic feeding was also used.

Adolescent↗