Life without water: expression of plant LEA genes by an anhydrobiotic arthropod

Anhydrobiotic animals protect cellular architecture and metabolic machinery in the dry state, yet the molecular repertoire supporting this profound dehydration tolerance is not fully understood. For the desiccation-tolerant crustacean, Artemia franciscana, we report differential expression of two distinct mRNAs encoding for proteins that share sequence similarities and structural features with late-embryogenesis abundant (LEA) proteins originally discovered in plants. Bioinformatic analyses support assignment of the LEA proteins from A. franciscana to group 3. This eucoelomate species is the most highly evolved animal for which LEA gene expression has been reported. It is becoming clear that an ensemble of micromolecules and macromolecules is important for establishing the physical conditions required for cellular stabilization during drying in nature.     

Influence of promoter region variants of insulin-like growth factor pathway genes on the strength-training response of muscle phenotypes in older adults.

To examine the influence of insulin-like growth factor (IGF) pathway gene polymorphisms on muscle mass and strength responses to strength training (ST), we studied 128 White and Black men and women before and after a 10-wk single-leg knee extension ST program. One-repetition maximum strength, muscle volume (MV) via computed tomography, and muscle quality (MQ) were assessed at baseline and after 10 wk of ST. There was a significant combined IGF1 cytosine adenine (CA) repeat gene effect, which included both the IGF1 CA repeat main effect and IGF1 CA repeat x PPP3R1 insertion-deletion (I/D) gene x gene interaction effect, on the changes in strength (P < 0.01) and MQ (P < 0.05) with ST. There was a trend for a significant gene x gene interaction between IGF1 CA repeat and PPP3R1 I/D for changes in strength (P = 0.07) and MQ (P = 0.06) with ST. The influence of the PPP3R1 A-202C gene polymorphism on change in MV with ST approached significance (P = 0.06). The IGF1 CA repeat polymorphism had a significant influence on the change in strength and MV combined with ST (P < 0.05), whereas the influence of the PPP3R1 I/D polymorphism approached significance (P = 0.08). There were no associations between the IGFBP3 A-202C gene polymorphism and the muscle phenotypic responses to ST. These data suggest that two of the three IGF pathway gene polymorphisms identified in this study influence muscle phenotypic responses to ST in both black and white older men and women.     

Miocene Fossils Reveal Ancient Roots for New Zealand’s Endemic Mystacina (Chiroptera) and Its Rainforest Habitat

The New Zealand endemic bat family Mystacinidae comprises just two Recent species referred to a single genus, Mystacina. The family was once more diverse and widespread, with an additional six extinct taxa recorded from Australia and New Zealand. Here, a new mystacinid is described from the early Miocene (19–16 Ma) St Bathans Fauna of Central Otago, South Island, New Zealand. It is the first pre-Pleistocene record of the modern genus and it extends the evolutionary history of Mystacina back at least 16 million years. Extant Mystacina species occupy old-growth rainforest and are semi-terrestrial with an exceptionally broad omnivorous diet. The majority of the plants inhabited, pollinated, dispersed or eaten by modern Mystacina were well-established in southern New Zealand in the early Miocene, based on the fossil record from sites at or near where the bat fossils are found. Similarly, many of the arthropod prey of living Mystacina are recorded as fossils in the same area. Although none of the Miocene plant and arthropod species is extant, most are closely related to modern taxa, demonstrating potentially long-standing ecological associations with Mystacina.     

Temporal and Nutritional Influences on the Response to Elevated CO2 in Selected British Grasses

To investigate the duration of the CO₂ response and its interactionwith mineral nutrition, CO₂-enrichment experiments were performedon four British grasses of differing ecology and functionaltype: Arrhenatherum elatius (L.) Beauv., Festuca ovina L., Festucarubra L. and Poa annua L. Naturally-lit, glasshouse cabinetswere used, with a non-limiting water supply and a daytime meantemperature of 18 °C. Two CO₂ treatments were maintainedat nominal concentrations of 350 and 700 vpm and were combinedfactorially with two levels of balanced mineral nutrition atconductivities of 0·1 and 1 mS cm^-1. Harvests took placeat planting-out, and at 16, 37 and 58 d thereafter. Fitted curves were used to derive instantaneous values of totaldry weight, relative growth rate (RGR), shoot weight fraction(SWF) and unit shoot rate (USR) for all combinations of species,CO₂ level, nutrient level and time of harvesting. At the higher nutrient level there was a reasonably close agreementwith previous estimates of the CO₂ response in the four species.The response, if any, most often arose from an increase in USRbeing accompanied by a less than proportionate decline in SWF.Responses were sustained throughout the period studied. At thelower nutrient level, all species showed a CO₂ response initially,but this declined at a rate which was inversely related to theCO₂-responsiveness of the species at the higher nutrient level. The underlying ontogenetic drift appeared to be markedly towardsadjustment in SWF and away from that of USR. However, this driftwas retarded, suspended or even reversed by low-nutrient conditionsand/or by high CO₂ responsiveness in the species itself.Copyright1995, 1999 Academic Press Climate change, CO₂ enrichment, plant strategies, mineral nutrition, growth analysis, relative growth rate, shoot weight fraction, unit shoot rate, functional equilibria     

Slow oscillations as a probe of the dynamics of the locus coeruleus-frontal cortex interaction in anesthetized rats

Multiunit or single unit activity recorded simultaneously from frontal cortex (FC) and locus coeruleus (LC) under ketamine anesthesia revealed that both regions show slow oscillatory activity, together or separately. If, however, both regions are engaged in this oscillatory activity, there is a systematic relationship between their phases with peak LC firing always following FC firing by 200–400 ms. This was confirmed by cross-correlational analyses, which indicated that the two structures temporarily form a resonant system. The FC-LC resonant state is, however, loose enough to remain open to other intrinsic or extrinsic influences, keeping the measured frequencies of oscillations at each site slightly different, as demonstrated by a delailed analysis of the autocorrelograms. An injection of lidocaine at the frontal cortex site, while sharply reducing the prefrontal activity to essentially zero, leads to an increase of the LC activity and to a modification of the shape of the LC autocorrelogram, but does not change appreciably the phase relationship between the activity in the two structures during the diminishing activity in FC.     

Targeting proteins to the lumen of endoplasmic reticulum using N-terminal domains of 11beta-hydroxysteroid dehydrogenase and the 50-kDa esterase.

Previous studies identified two intrinsic endoplasmic reticulum (ER) proteins, 11beta-hydroxysteroid dehydrogenase, isozyme 1 (11beta-HSD) and the 50-kDa esterase (E3), sharing some amino acid sequence motifs in their N-terminal transmembrane (TM) domains. Both are type II membrane proteins with the C terminus projecting into the lumen of the ER. This finding implied that the N-terminal TM domains of 11beta-HSD and E3 may constitute a lumenal targeting signal (LTS). To investigate this hypothesis we created chimeric fusions using the putative targeting sequences and the reporter gene, Aequorea victoria green fluorescent protein. Transfected COS cells expressing LTS-green fluorescent protein chimeras were examined by fluorescent microscopy and electron microscopic immunogold labeling. The orientation of expressed chimeras was established by immunocytofluorescent staining of selectively permeabilized COS cells. In addition, protease protection assays of membranes in the presence and absence of detergents was used to confirm lumenal or the cytosolic orientation of the constructed chimeras. To investigate the general applicability of the proposed LTS, we fused the N terminus of E3 to the N terminus of the NADH-cytochrome b5 reductase lacking the myristoyl group and N-terminal 30-residue membrane anchor. The orientation of the cytochrome b5 reductase was reversed, from cytosolic to lumenal projection of the active domain. These observations establish that an amino acid sequence consisting of short basic or neutral residues at the N terminus, followed by a specific array of hydrophobic residues terminating with acidic residues, is sufficient for lumenal targeting of single-pass proteins that are structurally and functionally unrelated.     

Activation of transglutaminase at calcium levels consistent with a role for this enzyme as a calcium receptor protein

The sensitivity of tissue transglutaminase to activation by Ca²⁺ and other cellular factors was investigated using the enzyme purified from rat liver. The inclusion of Mg²⁺ in the assay system appeared to reduce the Ca²⁺-requirement of the enzyme when native N,N-dimethylcasein was used as the protein acceptor substrate. However, when this protein was dephosphorylated, the Ca²⁺-requirement was unaffected by Mg²⁺. In addition, using this modified assay, a K_m for Ca²⁺ was calculated to be in the range of 3–4 M, at least an order of magnitude lower than that obtained with native acceptor substrate. Membrane phospholipids, 1,2-diolein and calmodufin were found not to affect the activation oftransglutaminase by Ca²⁺. The sensitivity of transglutaminase to Ca²⁺ which we have now demonstrated suggests that this enzyme may directly act as a receptor protein for Ca²⁺ during stimulusresponse coupling mediated by this cation.     

Enzyme modulation of the Golgi apparatus and GERL: a cytochemical study of parotid acinar cells

The distribution of thiamine pyrophosphatase (TPPase) and acid phosphatase (AcPase) has been examined in resting parotid acinar cells as well as during decreased and increased secretory granule production. In resting acinar cells, TPPase activity was restricted to the trans Golgi saccules and AcPase activity was localized in GERL and immature secretory granules. Although secretory granule production is diminished during ethionine intoxication, no significant alteration in the distribution of either TPPase or AcPase was noted. However, marked changes in enzyme localization, especially of TPPase, occurred during accelerated secretory granule production. The alterations were essentially the same for all of the conditions studied (recovery from ethionine treatment, recovery from a protein depletion diet, secretory stimulation with isoproterenol, and postnatal maturation of the parotid gland). During maximal secretory granule production, TPPase activity was localized not only in the trans Golgi saccules, but also in GERL-like cisternae and immature secretory granules. The immature secretory granules were often in continuity with the GERL-like cisternae. At the same time that the TPPase activity was increased, the AcPase activity was frequently diminished. These modulations in enzyme activity provide evidence that GERL is derived from the trans Golgi saccule.