Effects on temperature on spontaneous and thyroxine-stimulated locomotor activity of Atlantic cod

Spontaneous locomotor activity of cod Gadus morhua maintained at 6° C tripled from February to May. In contrast, locomotor activity of cod held at 2° C was significantly lower than at 6° C (between 25 and 65% lower) and the seasonal increase was smaller. Plasma levels of both thyroxine (T₄) and triiodothyronine (T₃) did not differ between 2 and 6° C. T₄ injection increased locomotor activity by 10% for both temperature regimes. These data indicate that low water temperature reduces locomotor activity associated with migration in cod and that thyroid hormones are not involved in this decrease. This study provides a possible mechanism through which cold waters may affects migration and distribution of cod via its Effects on locomotor activity and swimming speed.     

Population genetics of the American eel (Anguilla rostrata): FST = 0 and North Atlantic Oscillation effects on demographic fluctuations of a panmictic species

We performed population genetic analyses on the American eel (Anguilla rostrata) with three main objectives. First, we conducted the most comprehensive analysis of neutral genetic population structure to date to revisit the null hypothesis of panmixia in this species. Second, we used this data to provide the first estimates of contemporary effective population size (N_e) and to document temporal variation in effective number of breeders (N_b) in American eel. Third, we tested for statistical associations between temporal variation in the North Atlantic Oscillation (NAO), the effective number of breeders and two indices of recruit abundance. A total of 2142 eels from 32 sampling locations were genotyped with 18 microsatellite loci. All measures of differentiation were essentially zero, and no evidence for significant spatial or temporal genetic differentiation was found. The panmixia hypothesis should thus be accepted for this species. N_b estimates varied by a factor of 23 among 12 cohorts, from 473 to 10 999. The effective population size N_e was estimated at 10 532 (95% CI, 9312–11 752). This study also showed that genetically based demographic indices, namely N_b and allelic richness (Ar), can be used as surrogates for the abundance of breeders and recruits, which were both shown to be positively influenced by variation during high (positive) NAO phases. Thus, long‐term genetic monitoring of American glass eels at several sites along the North American Atlantic coast would represent a powerful and efficient complement to census monitoring to track demographic fluctuations and better understand their causes.     

SRAP Polymorphisms Associated to Cell Wall Degradability in Lignified Stems of Alfalfa

The identification of DNA polymorphisms associated to increased cell wall (CW) degradability could accelerate the development of alfalfa (Medicago sativa L.) cultivars with superior ethanol conversion yields. Genotypes with high (D+) or low (D?) CW degradability were recently identified within a biomass-type and three winter-hardy-type populations using near-infrared reflectance spectroscopy (NIRS) prediction of CW glucose released by enzyme saccharification. In this report, we used sequence-related amplified polymorphism to search for DNA variations associated to differences in enzyme-released glucose. A bulk segregant analysis (BSA) of pooled DNA samples (20 plants/bulk) from D+, D?, and randomly chosen genotypes uncovered polymorphisms associated to CW degradability. Polymorphisms that increase or decrease in intensity between D+ and D? bulks indicated the presence of genomic regions with either positive or negative effects on CW degradability. A primer pair (Me4-R14) generated a fragment, which increased in intensity in the D+ bulk of the biomass-type population. Conversely, the amplification of that fragment declined in the D+ bulks of the winter-hardy-type populations. Interestingly, these populations differ in their degradability. Assessment of the genotypic occurrence of this fragment confirmed that polymorphism detected with BSA reflects changes in the frequency of occurrence within populations. Sequence analysis of the Me4-R14 fragment revealed homologies with sequences from Medicago truncatula, a model species for legumes with documented synteny with M. sativa. Our results show that genomic regions associated to CW degradability can be identified using the combination of BSA of genotypes with contrasted degradability and a PCR-based amplification technique.     

Nuclear lactate dehydrogenase modulates histone modification in human hepatocytes

It is becoming increasingly apparent that the nucleus harbors metabolic enzymes that affect genetic transforming events. Here, we describe a nuclear isoform of lactate dehydrogenase (nLDH) and its ability to orchestrate histone deacetylation by controlling the availability of nicotinamide adenine dinucleotide (NAD⁺), a key ingredient of the sirtuin-1 (SIRT1) deacetylase system. There was an increase in the expression of nLDH concomitant with the presence of hydrogen peroxide (H₂O₂) in the culture medium. Under oxidative stress, the NAD⁺ generated by nLDH resulted in the enhanced deacetylation of histones compared to the control hepatocytes despite no discernable change in the levels of SIRT1. There appeared to be an intimate association between nLDH and SIRT1 as these two enzymes co-immunoprecipitated. The ability of nLDH to regulate epigenetic modifications by manipulating NAD⁺ reveals an intricate link between metabolism and the processing of genetic information.     

Shared ancestral polymorphisms and chromosomal rearrangements as potential drivers of local adaptation in a marine fish

Gene flow has tremendous importance for local adaptation, by influencing the fate of de novo mutations, maintaining standing genetic variation and driving adaptive introgression. Furthermore, structural variation as chromosomal rearrangements may facilitate adaptation despite high gene flow. However, our understanding of the evolutionary mechanisms impending or favouring local adaptation in the presence of gene flow is still limited to a restricted number of study systems. In this study, we examined how demographic history, shared ancestral polymorphism, and gene flow among glacial lineages contribute to local adaptation to sea conditions in a marine fish, the capelin (Mallotus villosus). We first assembled a 490‐Mbp draft genome of M. villosus to map our RAD sequence reads. Then, we used a large data set of genome‐wide single nucleotide polymorphisms (25,904 filtered SNPs) genotyped in 1,310 individuals collected from 31 spawning sites in the northwest Atlantic. We reconstructed the history of divergence among three glacial lineages and showed that they probably diverged from 3.8 to 1.8 million years ago and experienced secondary contacts. Within each lineage, our analyses provided evidence for large N_e and high gene flow among spawning sites. Within the Northwest Atlantic lineage, we detected a polymorphic chromosomal rearrangement leading to the occurrence of three haplogroups. Genotype–environment associations revealed molecular signatures of local adaptation to environmental conditions prevailing at spawning sites. Our study also suggests that both shared polymorphisms among lineages, resulting from standing genetic variation or introgression, and chromosomal rearrangements may contribute to local adaptation in the presence of high gene flow.     

Production of a diagnostic monoclonal antibody in perennial alfalfa plants.

The increasing use of monoclonal antibodies (mAbs) in diagnostic reagents necessitates efficient and cost-effective mAb production methods. In blood banks, one of the most routinely used reagents is the anti-human IgG reagent used for the detection of non-agglutinating antibodies. Here we report the production of a functional, purified anti-human IgG, through the expression of its encoding genes in perennial transgenic alfalfa. Transgenic plants expressing the light- and heavy-chain encoding mRNAs were obtained, and plants from crosses were found to express fully assembled C5-1. The purification procedure yielded mainly the H2L2 form with specificity and affinity identical to those of hybridoma-derived C5-1. The ability to accumulate the antibody was maintained both in parental F1 lines during repeated harvesting and in clonal material; the antibody was stable in the drying hay as in extracts made in pure water. Also, plant and hybridoma-derived C5-1 had similar in vivo half-lives in mice. These results indicate that plant C5-1 could be used in a diagnostic reagent as effectively as hybridoma-derived C5-1, and demonstrates the usefulness of perennial systems for the cost-effective, stable, and reliable production of large amounts of mAbs.     

Prediction of q-values and conformations of gadolinium chelates for magnetic resonance imaging

For gadolinium chelates, we determined that there is a linear correlation between calculated solvent-accessible surface area and q-value, the number of rapidly exchanging water molecules directly bound to the gadolinium ion. A calibration curve was developed to predict q-value based on the solvent-accessible surface area of gadolinium. This predictive method was validated with the following gadolinium crystal structures: (ethylenediaminetetraacetic acid)-gadolinium(III) [Gd(EDTA)] [Templeton, L. K., Templeton, D. H., Zalkin, A., and Ruben, H. W. (1982) Anomalous Scattering by Praseodymium, Samarium, and Gadolinium and Structures of their Thylenediaminetetraacetate (EDTA) Salts. Acta Crystallogr., Sect. B 38, 2155], (1,4,7,10-tetraazacyclododecane-N,N',N' ',N' "-tetraacetic acid)-gadolinium(III) [Gd(DOTA)] [Dubost, J.-P., Leger, J.-M., Langlois, M.-H., Meyer, D., and Schaefer, M. (1991) Structure of a Magnetic Resonance Imaging Agent - The Gadolinium-DOTA Complex C(16)H(24)N(4)O(8)NaGd, 5H(2)O. C. R. Acad. Sci., Ser. 2 312, 349], (diethylenetriaminepentaacetic acid)-gadolinium(III) [Gd(DTPA)] [Stezowski, J. J., and Hoard, J. L. (1984) Heavy Metal Ionophores - Correlations Among Structural Parameters of Complexed Nonpeptide Polyamino Acids. Isr. J. Chem. 24, 323], (diethylenepenta-acetato)-gadolinium(III) [Gd(DTPA-BEA)] [Smith, P. H., Brainard, J. R., Morris, D. E., Jarvinen, G. D., and Ryan, R. R. (1989) Solution and Solid-State Characterization of Europium and Gadolinium Schiff-Base Complexes and Assessment of their Potential as Contrast Agents in Magnetic Resonance Imaging. J. Am. Chem. Soc. 111, 7437], and (1,7,13-triaza-4,10, 16-trioxacyclo-octadecane-N,N',N' '-triacetato)-gadolinium(III) [Gd(TTTA)] [Chen, D., Squattrito, P. J., Martell, A. E., and Clearfield, A. (1990) Synthesis and Crystal Structure of a 9-Coordinate Gadolinium(III) Complex of 1,7,13-Triaza-4,10, 16-Trioxacyclooctadecane-N,N',N' '-Tri-Acetic Acid. Inorg. Chem. 29, 4366]. Predicted q-values were in complete agreement with experimentally determined q-values. A genetic algorithm-based conformational search method was developed to generate valid 3D models for gadolinium chelates. The method was successfully tested on the following gadolinium chelates: Gd(EDTA) (Templeton et al., 1982), Gd(DOTA) (Dubost et al., 1991), Gd(DTPA-BEA) (Smith et al., 1989), Gd(TTTA) (Chen et al., 1990), Gd(triethylene glycol) [Rogers, R. D., Voss, E. J., and Etzenhouser, R. D. (1988) F-Element Crown Ether Complexes. 17. Synthetic and Structural Survey of Lanthanide Chloride Tiethylene Glycol Complexes. Inorg. Chem. 27, 533], and Gd(tetraethylene glycol) [Rogers, R. D., Etzenhouser, R. D., Murdoch, J. S., and Reyes, E. (1991) Macrocycle Complexation Chemistry. 35. Survey of the Complexation of the Open-Chain 15-Crown-5 Analogue tetraethylene Glycol with the Lanthanide Chlorides. Inorg. Chem. 30, 1445].     

Criteria for Internal Mammary Artery Implantation Based on Cine Coronary Arteriography

Preoperative coronary arteriograms were correlated, in a group of 50 patients, with left internal mammary angiograms obtained from 11 to 32 months, with a mean of 17 months, after mammary artery implantation. In all patients in whom the internal mammary artery was patent and considered functional with good angiographic opacification of the anterior descending coronary artery, the preoperative coronary angiogram showed total or subtotal obstruction of the latter vessel, with indirect evidence of decreased flow and pressure distal to the obstruction. This evidence was provided by the presence of a collateral circulation or, in a few cases of subtotal obstruction, delayed opacification of the vessel distal to the obstruction.In patients in whom the internal mammary artery was patent but showed no anastomotic connection with the anterior descending coronary artery or only opacification of small coronary branches, the degree of coronary obstruction was, in most cases, less than 90% of the lumen of the coronary artery in the absence of any collateral circulation or delayed opacification of the vessel distal to the obstruction.Occlusion of the internal mammary artery was seen as often in the presence of total or subtotal obstructions as with lesser degrees of anterior descending coronary artery obstruction, and is believed unrelated to the degree of pre-existing coronary artery disease.Successful internal mammary artery implantation can be related to specific coronary angiographic patterns recognizable before operation; these may serve as reliable criteria for the selection of patients.     

The Tyrosine Phosphatase STEP Is Involved in Age-Related Memory Decline

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