Polysome Metabolism In Winter Rye (secale Cereale Cv Puma)

The effect of growth at low temperature on polysome metabolism in winter rye (Secale cereale cv Puma) has been investigated. A method for isolation of highly polymerized polysomes from mature leaf tissues has been developed. The degree of intactness of isolated polysomes was monitored by two independent but complementary methods: size class distribution on sucrose gradients and in vitro translation. The composition of the optimal polysome isolation buffer for mature rye leaves is similar for leaves grown at low (5{dollar}\sp\circ{dollar}) or high (20{dollar}\sp\circ{dollar}) temperature but different from that reported for young tobacco and pea leaves. The quantity of polysomes (per unit DNA) increases by a factor of 2.7 at low temperature. These polysomes are larger and their melting point is decreased by 3.7{dollar}\sp\circ.{dollar} Analysis of ribosome composition by one- and two-dimensional electrophoresis revealed that only a few peripheral ribosomal proteins (and possibly a subunit of initiation factor 3) are modified. No significant change in the rRNA could be detected. Polysomes isolated from leaves grown at low temperature incorporate twice as much label as polysomes isolated from control plants, regardless of the temperature of translation. Polysomes from low temperature plants require higher magnesium levels for optimal translation and were more sensitive to detergent. Electrophoretic analysis of translation products revealed that some transcripts are newly expressed (16 kD to 170 kD), some are repressed (35 kD to 105 kD) and others increase or decrease in quantity. It is suggested that growth of rye at low temperature leads to alterations in both the ribosome conformation and peripheral proteins which in turn provides for a more efficient translation system. Enhanced translational activity does not appear to be due to the mRNA, although transcription does appear to be altered at low temperature. These changes are considered significant in the adaptation and growth of rye at low temperature

Metabolic control analysis is helpful for informed genetic manipulation of oilseed rape (Brassica napus) to increase seed oil content

Top–down control analysis (TDCA) is a useful tool for quantifying constraints on metabolic pathways that might be overcome by biotechnological approaches. Previous studies on lipid accumulation in oilseed rape have suggested that diacylglycerol acyltransferase (DGAT), which catalyses the final step in seed oil biosynthesis, might be an effective target for enhancing seed oil content. Here, increased seed oil content, increased DGAT activity, and reduced substrate:product ratio are demonstrated, as well as reduced flux control by complex lipid assembly, as determined by TDCA in Brassica napus (canola) lines which overexpress the gene encoding type-1 DGAT. Lines overexpressing DGAT1 also exhibited considerably enhanced seed oil content under drought conditions. These results support the use of TDCA in guiding the rational selection of molecular targets for oilseed modification. The most effective lines had a seed oil increase of 14%. Moreover, overexpression of DGAT1 under drought conditions reduced this environmental penalty on seed oil content

Differential Susceptibility of Interneurons Expressing Neuropeptide Y or Parvalbumin in the Aged Hippocampus to Acute Seizure Activity

Acute seizure (AS) activity in old age has an increased predisposition for evolving into temporal lobe epilepsy (TLE). Furthermore, spontaneous seizures and cognitive dysfunction after AS activity are often intense in the aged population than in young adults. This could be due to an increased vulnerability of inhibitory interneurons in the aged hippocampus to AS activity. We investigated this issue by comparing the survival of hippocampal GABA-ergic interneurons that contain the neuropeptide Y (NPY) or the calcium binding protein parvalbumin (PV) between young adult (5-months old) and aged (22-months old) F344 rats at 12 days after three-hours of AS activity. Graded intraperitoneal injections of the kainic acid (KA) induced AS activity and a diazepam injection at 3 hours after the onset terminated AS-activity. Measurement of interneuron numbers in different hippocampal subfields revealed that NPY+ interneurons were relatively resistant to AS activity in the aged hippocampus in comparison to the young adult hippocampus. Whereas, PV+ interneurons were highly susceptible to AS activity in both age groups. However, as aging alone substantially depleted these populations, the aged hippocampus after three-hours of AS activity exhibited 48% reductions in NPY+ interneurons and 70% reductions in PV+ interneurons, in comparison to the young hippocampus after similar AS activity. Thus, AS activity-induced TLE in old age is associated with far fewer hippocampal NPY+ and PV+ interneuron numbers than AS-induced TLE in the young adult age. This discrepancy likely underlies the severe spontaneous seizures and cognitive dysfunction observed in the aged people after AS activity

Chromosome-scale genome assembly provides insights into rye biology, evolution and agronomic potential

Rye (Secale cereale L.) is an exceptionally climate-resilient cereal crop, used extensively to produce improved wheat varieties via introgressive hybridization and possessing the entire repertoire of genes necessary to enable hybrid breeding. Rye is allogamous and only recently domesticated, thus giving cultivated ryes access to a diverse and exploitable wild gene pool. To further enhance the agronomic potential of rye, we produced a chromosome-scale annotated assembly of the 7.9-gigabase rye genome and extensively validated its quality by using a suite of molecular genetic resources. We demonstrate applications of this resource with a broad range of investigations. We present findings on cultivated rye's incomplete genetic isolation from wild relatives, mechanisms of genome structural evolution, pathogen resistance, low-temperature tolerance, fertility control systems for hybrid breeding and the yield benefits of rye-wheat introgressions.Peer reviewe

Caractéristiques de la chair de la truite arc en ciel : 1- composition chimique et cellularité du muscle et des tissus adipeux

Chemical composition and size of libre and adipose cells in the flesh of rainbow trout were studied. The flesh of fish includes a superficial red muscle which is composed of small fibres (beta red type) and a deep while muscle which is the main tissue and is composed essentially of a mosaic of small and large fibres (alpha white type). The mean size of muscle fibres increased with trout body weight. The amount of collagen in the flesh was low (below 1% of fresh muscle weight) and thermosoluble collagen seemed to be more variable than acidosoluble collagen. Thus, the quality of the flesh would depend on the characteristics of muscle tissues. Lipid content in the flesh of trout of market size reared in fresh water was low (below 10% of fresh weight) and it was located in abdominal and dorsal subcutaneous adipose tissues. Adipose tissues were generally composed of two populations of adipose cells, the small adipose cells (20/30 microns) beeing present in developing adipose tissue and large adipocytes whose size increased with the lipid content of the flesh

Caractéristiques de la chair de la truite arc en ciel : 2- composantes physiques et sensorielles

Some results on physical and sensory characteristics of the flesh of rainbow trout are reported. When fish was fed a diet not supplemented with carotenoid pigments, the color of the flesh was pale. The texture of the flesh of the trout assessed by physical and sensory tests was not tough and slightly elastic. The other parameters : smell, flavor or fat taste were low. Thus the flesh of rainbow trout is a rather neutral product. Texture of flesh assessed by instrumental methods and sensory evaluation was modified significantly by environnemental factors (temperature, water flow rate). Analysis of relationships between chemical composition and texture showed that lipid content affected texture of raw product but not that of cooked product

The Relationships between Plant Developmental Traits and Winter Field Survival in Rye (Secale cereale L.)

Overwintering cereals accumulate low temperature tolerance (LTT) during cold acclimation in the autumn. Simultaneously, the plants adjust to the colder season by making developmental changes at the shoot apical meristem. These processes lead to higher winter hardiness in winter rye varieties (Secale cereale L.) adapted to Northern latitudes as compared to other cereal crops. To dissect the winter-hardiness trait in rye, a panel of 96 genotypes of different origins and growth habits was assessed for winter field survival (WFS), LTT, and six developmental traits. Best Linear Unbiased Estimates for WFS determined from five field trials correlated strongly with LTT (r = 0.90, p < 0.001); thus, cold acclimation efficiency was the major contributor to WFS. WFS also correlated strongly (p < 0.001) with final leaf number (r = 0.80), prostrate growth habit (r = 0.61), plant height (r = 0.34), but showed weaker associations with top internode length (r = 0.30, p < 0.01) and days to anthesis (r = 0.25, p < 0.05). The heritability estimates (h2) for WFS-associated traits ranged from 0.45 (prostrate growth habit) to 0.81 (final leaf number) and were overall higher than for WFS (h2 = 0.48). All developmental traits associated with WFS and LTT are postulated to be regulated by phytohormone levels at shoot apical meristem

The Relationships between Plant Developmental Traits and Winter Field Survival in Rye (<i>Secale cereale</i> L.)

Overwintering cereals accumulate low temperature tolerance (LTT) during cold acclimation in the autumn. Simultaneously, the plants adjust to the colder season by making developmental changes at the shoot apical meristem. These processes lead to higher winter hardiness in winter rye varieties (Secale cereale L.) adapted to Northern latitudes as compared to other cereal crops. To dissect the winter-hardiness trait in rye, a panel of 96 genotypes of different origins and growth habits was assessed for winter field survival (WFS), LTT, and six developmental traits. Best Linear Unbiased Estimates for WFS determined from five field trials correlated strongly with LTT (r = 0.90, p p p 0.01) and days to anthesis (r = 0.25, p 0.05). The heritability estimates (h2) for WFS-associated traits ranged from 0.45 (prostrate growth habit) to 0.81 (final leaf number) and were overall higher than for WFS (h2 = 0.48). All developmental traits associated with WFS and LTT are postulated to be regulated by phytohormone levels at shoot apical meristem