The role of variable weather for the dynamics of a seed-seed predator system

Summary A simple model is presented describing the interaction between weather conditions, seed production of a longlived herb, Vincetoxicum hirundinaria (Asclepiadaceae), and abundance of a predispersal seed predator, Euphranta connexa (Diptera, Tephritidae). The model is used to investigate the role of weather-induced fluctuations in seed set on the interaction between plant and seed predator and the resulting longterm production of seeds escaping predispersal seed predation.As weather variability increases Euphranta populations become less effective in tracking their food resources, leading to increased longterm production of dispersing seeds. Occasional years of crop failure due to drought stress may thus in the long run be of benefit to the plant.     

Can resource use be the link between productivity and species richness in mammals?

Species richness has been shown to be affected by primary productivity at various spatial scales. However, the mechanisms behind this effect are still poorly understood. Under the assumption that primary productivity is directly related to energy availability for an animal assemblage, the hypotheses are that (i) primary productivity will affect the number of ways different food resources can be combined into species specific niches and (ii) it will also determine the number of specialist species that can be supported. These hypotheses were tested on the herbivorous mammalian fauna of Australia. Productivity only had a weak effect on the number of food resource combinations in this case. Specialization was most common at low and high productivity. In addition there were significant differences in where different types of specialization was the most common. This study seeks an energetic mechanism to explain an energetic relationship and though no clear effect was found for resource use it identified a possible link between productivity and species richness.     

Changes in physiological and neuroendocrine properties during thermal adaptation of golden hamsters (Mesocricetus auratus)

Summary Golden hamsters raised at 22°C were adapted in the early summer for 3 weeks to either 28°C or 5°C. To achieve profound changes the photoperiod was also shortened from 14 h to 11 h during adaptation to cold. During the investigation body weight, food consumption, water intake, urine production, and osmolality, as well as secreted amounts of noradrenaline (NA) and dopamine (DA), were recorded in each animal before, during, and after the adaptation period. In another group of golden hamsters the brains were processed for immunocytochemical detection of arginine-vasopressin (AVP) and corticotropin releasing factor (CRF) in the third week of adaptation to a cold or warm environment. In warm-adapted animals food and water consumption and urine production remained unchanged or were only slightly reduced. NA and DA secretion were reduced by 50%. The AVP-immunoreactivity reflected an antidiuretic state in these animals. In fibers influencing the adrenal axis, AVP-immunoreactivity was weak compared to CRF fibers. Food and water consumption, urine production, and DA secretion increased two-fold during cold adaptation. Daily secreted amounts of NA increased nine-fold. AVP-immunoreactivity was weak in projections to the neurohypophysis. Fibers influencing the adrenal axis, however, displayed strong AVP-immunoreactivity in comparison to that of CRF. The immunocytochemically determined patterns of AVP and CRF distribution indicated an activation of the osmoregulative axis in the warm-adapted animals and of the adrenal axis in the cold-adapted golden hamsters.Abbreviations NA noradrenaline - DA dopamine - AVP argininevasopressin - CRF corticotropin releasing factor - SON supraoptic nucleus     

Allopolyploid evolution in Geinae (Colurieae: Rosaceae) – building reticulate species trees from bifurcating gene trees

A previous phylogenetic study of paralogous nuclear low-copy granule-bound starch synthase (GBSSI) gene sequences from polyploid and diploid species in Geinae indicated that the clade has experienced two major allopolyploid events in its history. These were estimated to have occurred several million years ago. In this extended study we test if the reticulate phylogenetic hypothesis for Geinae can be maintained when additional sequences are added. The results are compatible with the hypothesis and strengthen it in minor aspects. We also attempt to identify extant members of one of the inferred ancestral lineages of the allopolyploids. On the basis of previous molecular phylogenies, one specific group has been proposed to be the descendants of this taxon. However, none of the additional paralogues belong to this ancestral lineage. A general method is proposed for converting a bifurcating gene tree, with multiple paralogous low-copy gene sequences from allopolyploid taxa, into a reticulate species tree.     

Metabolism before,during and after anaesthesia in colic and healthy horses

Background  

Many colic horses are compromised due to the disease state and from hours of starvation and sometimes long trailer rides. This could influence their muscle energy reserves and affect the horses' ability to recover. The principal aim was to follow metabolic parameter before, during, and up to 7 days after anaesthesia in healthy horses and in horses undergoing abdominal surgery due to colic.     

Candida suecica sp.n. isolated from marine environment

A new species ofCandida was isolated from marine environment. It ferments glucose slowly. It assimilates cellobiose but does not split arbutin. It does not assimilate nitrate. Maximum temperature is ±28 C. The proposed name isCandida suecica.     

DNA-DEPENDENT RNA POLYMERASES FROM RAT BRAIN, AND RNA SYNTHESIS IN GLIAL AND NEURONAL CELL-ENRICHED FRACTIONS, AFTER PROTEIN RESTRICTION

Abstract— An assay for the dopaminergic agonist, apomorphine, is described. The assay is capable of detecting as little as 3 pmol of apomorphine. The basis of the assay is the O-methylation of apomorphine utilizing S-[methyl-³H]adenosyl-L-methionine and a partially purified catechol-O-methyl transferase to form [methyl-³H]apocodeine. The radiolabeled apocodeine is purified by solvent partition. Following systemic administration of apomorphine, the compound is uniformly distributed throughout the brain of the rat: there is no selective accumulation of apomorphine in dopaminergic regions of the brain. The level of apomorphine found in the substantia nigra is as great as the level found in the caudate-putamen. This latter observation, in addition to a variety of other evidence, raises the possibility that some of the in vivo effects of apomorphine may occur via an action of the drug within the substantia nigra, rather than by an action within the caudate-putamen.