Trophic relationships of muskoxen (Ovibos moschatus) and reindeer (Rangifer tarandus) on Wrangel Island

Seasonal changes in the diets of muskoxen and reindeer on Wrangel Island have been studied. The results are discussed with respect to consumption of basic forage plants depending on the feeding strategies and biotopic distribution of the two species.     

Turing on Super-Turing and adaptivity

Biological processes are often compared to computation and modeled on the Universal Turing Machine. While many systems or aspects of systems can be well described in this manner, Turing computation can only compute what it has been programmed for. It has no ability to learn or adapt to new situations. Yet, adaptation, choice and learning are all hallmarks of living organisms. This suggests that there must be a different form of computation capable of this sort of calculation. It also suggests that there are current computational models of biological systems that may be fundamentally incorrect. We argue that the Super-Turing model is both capable of modeling adaptive computation, and furthermore, a possible answer to the computational model searched for by Turing himself.     

Photoreactions of phosphorothioate and cysteamine-S-phosphate: Photosubstitution and photophosphoryl transfer

The photoreactions of phosphorothioate and cysteamine-S-phosphate were investigated. On irradiation of phosphorothiote a marked change in absorption spectrum was observed. The product migrated in high voltage electrophoresis, with different mobility from that of phosphorothiote and its dimer, or inorganic orthophosphate. It contained phosphare and sulfur in a ratio of 2 : 1, without reducing properties. Therefore it was suggested that the product is either pyrothiophosphate, or a cyclic compound, with similar composition.On irradiation of phosphorothiote in the presence of potential phosphoryl group acceptor, such as glucose or galactose, 25–40% of the phosphoryl group was transferred. The formation of glucose 6-phosphate, or galactose 6-phosphate was observed. The photolysis of cysteamine-S-phosphate gave cysteamine, inorganic orthophosphate and taurine.Under the same conditions of irradiation, inorganic orthophosphate or aminoethanol-O-phosphate were found to be stable.     

AT1R-CB₁R heteromerization reveals a new mechanism for the pathogenic properties of angiotensin II

The mechanism of G protein-coupled receptor (GPCR) signal integration is controversial. While GPCR assembly into hetero-oligomers facilitates signal integration of different receptor types, cross-talk between Gαi- and Gαq-coupled receptors is often thought to be oligomerization independent. In this study, we examined the mechanism of signal integration between the Gαi-coupled type I cannabinoid receptor (CB(1)R) and the Gαq-coupled AT1R. We find that these two receptors functionally interact, resulting in the potentiation of AT1R signalling and coupling of AT1R to multiple G proteins. Importantly, using several methods, that is, co-immunoprecipitation and resonance energy transfer assays, as well as receptor- and heteromer-selective antibodies, we show that AT1R and CB(1)R form receptor heteromers. We examined the physiological relevance of this interaction in hepatic stellate cells from ethanol-administered rats in which CB(1)R is upregulated. We found a significant upregulation of AT1R-CB(1)R heteromers and enhancement of angiotensin II-mediated signalling, as compared with cells from control animals. Moreover, blocking CB(1)R activity prevented angiotensin II-mediated mitogenic signalling and profibrogenic gene expression. These results provide a molecular basis for the pivotal role of heteromer-dependent signal integration in pathology.     

Barnacle Goose (Branta leucopsis) feeding ecology and trophic relationships on Kolguev Island: The usage patterns of nutritional resources in tundra and seashore habitats

Insight into colonization of new areas by invasive species and their relationships with aboriginal species is a major challenge in ecology, allowing for prediction of the outcome of biological invasions. In this context, the current expansion of the Barnacle Goose (Branta leucopsis) is of great interest. The seasonal dynamics of Barnacle Goose feeding and the structure of its diet on Kolguev Island during the nesting and postnesting periods (May 27–July 29) have been examined. The diet structures of the invasive Barnacle Goose and the aboriginal species White-fronted goose (Anser albifrons) and Bean goose (A. fabalis) have been compared. The probability of interspecific competition and the ecological advantages in the diet patterns of these species have been estimated. If the Barnacle Goose population on Kolguev Island continues to increase, this may led to a decline in the population of aboriginal species of geese on the island.     

Calmodulin Methyltransferase Is Required for Growth,Muscle Strength,Somatosensory Development and Brain Function

Calmodulin lysine methyl transferase (CaM KMT) is ubiquitously expressed and highly conserved from plants to vertebrates. CaM is frequently trimethylated at Lys-115, however, the role of CaM methylation in vertebrates has not been studied. CaM KMT was found to be homozygously deleted in the 2P21 deletion syndrome that includes 4 genes. These patients present with cystinuria, severe intellectual disabilities, hypotonia, mitochondrial disease and facial dysmorphism. Two siblings with deletion of three of the genes included in the 2P21 deletion syndrome presented with cystinuria, hypotonia, a mild/moderate mental retardation and a respiratory chain complex IV deficiency. To be able to attribute the functional significance of the methylation of CaM in the mouse and the contribution of CaM KMT to the clinical presentation of the 2p21deletion patients, we produced a mouse model lacking only CaM KMT with deletion borders as in the human 2p21deletion syndrome. No compensatory activity for CaM methylation was found. Impairment of complexes I and IV, and less significantly III, of the mitochondrial respiratory chain was more pronounced in the brain than in muscle. CaM KMT is essential for normal body growth and somatosensory development, as well as for the proper functioning of the adult mouse brain. Developmental delay was demonstrated for somatosensory function and for complex behavior, which involved both basal motor function and motivation. The mutant mice also had deficits in motor learning, complex coordination and learning of aversive stimuli. The mouse model contributes to the evaluation of the role of methylated CaM. CaM methylation appears to have a role in growth, muscle strength, somatosensory development and brain function. The current study has clinical implications for human patients. Patients presenting slow growth and muscle weakness that could result from a mitochondrial impairment and mental retardation should be considered for sequence analysis of the CaM KMT gene.     

Polyglucosan neurotoxicity caused by glycogen branching enzyme deficiency can be reversed by inhibition of glycogen synthase

Uncontrolled elongation of glycogen chains, not adequately balanced by their branching, leads to the formation of an insoluble, presumably neurotoxic, form of glycogen called polyglucosan. To test the suspected pathogenicity of polyglucosans in neurological glycogenoses, we have modeled the typical glycogenosis Adult Polyglucosan Body Disease (APBD) by suppressing glycogen branching enzyme 1 (GBE1, EC 2.4.1.18) expression using lentiviruses harboring short hairpin RNA (shRNA). GBE1 suppression in embryonic cortical neurons led to polyglucosan accumulation and associated apoptosis, which were reversible by rapamycin or starvation treatments. Further analysis revealed that rapamycin and starvation led to phosphorylation and inactivation of glycogen synthase (GS, EC 2.4.1.11), dephosphorylated and activated in the GBE1‐suppressed neurons. These protective effects of rapamycin and starvation were reversed by overexpression of phosphorylation site mutant GS only if its glycogen binding site was intact. While rapamycin and starvation induce autophagy, autophagic maturation was not required for their corrective effects, which prevailed even if autophagic flux was inhibited by vinblastine. Furthermore, polyglucosans were not observed in any compartment along the autophagic pathway. Our data suggest that glycogen branching enzyme repression in glycogenoses can cause pathogenic polyglucosan buildup, which might be corrected by GS inhibition.

     

Cell and tissue dynamics of olive endocarp sclerification vary according to water availability

Endocarp developmental timing in drupe‐type fruits, involving tissue expansion and sclerification processes, is increasingly used as marker for biological studies and crop management. In spite of its wide application, however, little is known regarding how these morphogenetic processes unfold or the factors that modify it. This study evaluates endocarp expansion and sclerification of olive (Olea europaea) fruits, used as an example of drupe‐type fruits, from trees growing under different water regimes: full irrigated, deficit irrigated (moderate reduction of water availability) and rainfed (severe reduction of water availability). Fruits were sampled weekly until pit hardening, and fruit and endocarp areas were evaluated in histological preparations. An image analysis process was tested and adjusted to quantify sclerified area and distribution within the endocarp. Individual stone cells differentiated independently but distribution and timing indicated the overall coordination of endocarp tissue sclerification. Increase in sclerified area was initially gradual, accelerated abruptly the week prior to the end of endocarp expansion and then continued at an intermediate rate. These results suggest that the end of the expansion period is driven by sclerification and the morphogenetic signals involved act first on sclerification rather than endocarp size. Intensification of sclerification and the end of expansive growth occurred first with lowest water supply. Moderate and severe reductions in water availability proportionately decreased endocarp expansion and prolonged the sclerification, delaying the date of physically perceived hardening but not affecting the final degree of endocarp sclerification.     

Receptor-type PTP-NP inhibition of Dynamin-1 GTPase activity is associated with neuronal depolarization

Dynamin-1 is a GTP-hydrolyzing protein and a key element in the clathrin-mediated endocytosis of secretory granules and neurovesicles at the plasma membrane. The unique receptor-like protein tyrosine phosphatase, PTP-NP/Phogrin/IAR/IA-2, is associated with neuroendocrine secretory granules and is highly expressed in the brain. Here, we show by confocal microscopy and biochemical studies that PTP-NP rapidly associates with Dynamin-1 in a depolarization-dependent manner and regulates Dynamin-1 GTPase activity upon KCl depolarization of rat primary hippocampal neurons. Depolarization of primary neurons induced direct association of PTP-NP with Dynamin-1 within 30 s. This association resulted in significant inhibition of Dynamin-1 GTPase activity (approximately 75% inhibition). Mutation within the phosphatase domain of PTP-NP (PTP-NP(D947A)) abolished the direct interaction of PTP-NP with Dynamin-1 and failed to inhibit Dynamin-1 GTPase activity. To further confirm the endogenous interaction of Dynamin-1 with wild-type PTP-NP, Dynamin-1 was purified biochemically from rat brain and its interaction with purified PTP-NP was analyzed. Highly purified Dynamin-1 specifically associated with wild-type PTP-NP and not with mutated PTP-NP, resulting in significant inhibition (approximately 70%) of Dynamin-1 GTPase activity. This is the first report to suggest a novel function of this unique receptor-type tyrosine phosphatase as a potential regulator of Dynamin-1 GTPase activity upon neuronal depolarization.