Evidence for mate‐encounter Allee effect in an invasive longhorn beetle (Coleoptera: Cerambycidae)

1. Limited empirical support is available for mate‐encounter Allee effects in invasive insects due to the logistical challenges of studying demographic trends in low‐density populations. 2. Traps baited with pheromone and spruce volatiles were used to monitor the abundance of female Tetropium fuscum F. (Coleoptera: Cerambycidae) at multiple sites in Nova Scotia in 2011 and 2012. Each female was dissected to determine the presence or absence of sperm in its spermatheca (mated or virgin female, respectively). 3. Both male and total T. fuscum abundance declined with increasing distance to the focal point of T. fuscum's invasion. Female mating probability declined with male abundance and with distance from the invasion focus, and mating probabilities were very low at the most peripheral sites. Difficulty in encountering mates may thus contribute to limiting the spread of T. fuscum. 4. The approach outlined here could be integrated into existing surveys of wood borers using traps baited with semiochemicals to improve our understanding of the role of the mate‐encounter Allee effect in invasion dynamics.     

Conservation of a cytoplasmic carboxy-terminal domain of connexin 43, a gap junctional protein,in mammal heart and brain

Summary According to the sequence of connexin 43, a cardiac gap junctional protein, the domain contained within residues 314–322 is located 60 amino acids away from the carboxy-terminus. Antibodies raised to a peptide corresponding to this domain label a unique 43-kD protein on immunoblots of both purified gap junctions and whole extracts from rat heart. Immunofluorescence investigations carried out on mammal heart sections reveal a pattern consistent with the known distribution of intercalated discs. Immunogold labeling performed with ultrathin frozen sections of rat heart or partially purified rat heart gap junctions demonstrate that antigenic determinants are associated exclusively with the cytoplasmic surfaces of gap junctions.The antibodies were shown to cross-react with a 43-kD protein on immunoblots of whole extracts from human, mouse and guinea pig heart. However, no labeling was seen when heart of lower vertebrates such as chicken, frog and trout, was investigated. These results, confirmed by immunofluorescence investigations, were interpreted as a loss of antigenic determinants due to sequence polymorphism of cardiac connexin 43.Proteins ofM _r 43 and 41 kD, immunologically related to cardiac connexin 43, were detected in immunoblots of mouse and rat brain whole extracts. mRNAs, homologous to those of cardiac connexin 43 and of the same size (3.0 kb), are also present in brain. Immunofluorescence investigations with primary cultures of unpermeabilized and permeabilized mouse neural cells showed that the antigenic determinants recognized by the antibodies specific for connexin 43 are cytoplasmic and that the labeling observed between clustered flat cells, is punctate, as expected for gap junctions. Double labeling experiments demonstrated that the immunoreactivity is associated with GFAP-positive cells, that is to say, astrocytes.     

Performance of the isolated and perfused working heart of the teleostConger conger: study of the inotropic effect of prostacyclin

Summary An in vitro preparation of the heart of the teleostConger conger, isolated without the pericardium, was set up. The procedure allowed subambient pressures to develop in the perfusion chamber during contraction, mimicking the in vivo situation with the pericardium intact. The ventricle produced a cardiac output of about 15 ml·min^-1·kg wet body weight^-1 at subambient input pressure, and was able to double the stroke work with an increase of preload up to about 0.2 kPa. Using this preparation it was found that prostacyclin has a positive inotropic effect on the atrium and ventricle, but it does not affect the heart rate. Semilogarithmic doseresponse curves of prostacyclin on the atrium are reported, showing a threshold concentration of about 10^-9 M. The isolated and perfusedConger conger heart provides a useful model for a detailed analysis of the action of prostacyclin on myocardial contractility.     

Developmental changes of the glycolytic enzymes in the human fetal heart

The ontogeny of hexokinase, phosphofructokinase, phosphoglucoisornerase, aldolase, pyruvate kinase and lactate dehydrogenase activities which are associated with glycolysis, an important energy yielding process, has been studied in human fetal heart for periods ranging from 13 weeks to above 33 weeks of gestation. Hexokinase, phosphoglucoisomerase and pyruvate kinase activities show similar developmental profiles exhibiting maximum activity at 25–28 weeks ofgestation. Phosphofructokinase activity, on the other hand, shows a minimum at this period and exhibits a peak value at early stages (13–16 weeks of gestation). Though considerable activity for aldolase is observed at an early period, it declines thereafter, but again increases in the later period. The probable role and correlations of these glycolytic enzymes with energy demand and general functional development in human fetal heart in ontogeny are evaluated.     

丁酸钠对大鼠离体灌流心脏细胞核组蛋白乙酰化的影响

本文用离体心脏灌流技术研究了丁酸钠对~3H-乙酰基参入大鼠心脏细胞核纽蛋白的影响。用蔗糖梯度离心将大鼠离体灌流心脏的细胞核分为心肌的和非心肌的,分别提取组蛋白。尿素-丙烯酰胺凝胶电泳将组蛋白分为五个组分。其比放射性测定的结果表明,~3H-乙酰基只参入核心组蛋白,程度为H_3>H_(2b)>H_4>H_(2a)。Triton-尿素-丙烯酰胺凝胶电泳图放射自显影结果显示,无论心肌细胞核还是非心肌细胞核,在丁酸钠为1m mol/L情况下,组蛋白H_3又可见三个亚组分(H_(3_1)、H_(3_2)及H_(3_3)),H_4可分出四个亚组分(H_(4_1)、H_(4_2)、H_(4_3)及H_(4_4));其总组蛋白乙酰化程度减低至对照组数值的60％。“冷追击”实验的结果提示,丁酸钠引起高乙酰化组蛋白的积蓄,确是通过其对组蛋白脱乙酰基过程的抑制作用而实现的。     

Uptake of Amino Acids by Brain Micro vessels Isolated from Rats with Experimental Chronic Renal Failure

The neurological disorders seen in patients with chronic renal failure and liver cirrhosis are analogous. Previous in vivo studies have shown that the impaired blood-brain amino acid transport seen in rats with chronic renal failure is similar to that of rats with portocaval anastomosis. To elucidate whether a comparable underlying pathogenic mechanism plays a role in both pathological conditions, blood and brain amino acid levels together with amino acid transport by isolated brain microvessels have been studied in rats with chronic renal failure and in sham-operated rats. Brain microvessels isolated from rats with experimental chronic renal failure showed that the uptake of labeled large neutral amino acid, i.e., leucine or phenylalanine, but not of lysine or alpha-methylaminoisobutyric acid, was significantly increased with respect to sham-operated rats; conversely, the uptake of glutamic acid in rats with chronic renal failure was significantly lower compared with values in controls. Kinetic analysis indicated that this was mainly due to increased exchange transport activity (Vmax) of the L-system, rather than to changes in the affinity (Km) of the carrier system for the relative substrate. These data, together with the significant rise of brain glutamine levels and an increased brain-to-plasma ratio of the sum of large neutral amino acids, are analogous to what was previously observed in rats with portocaval anastomosis.(ABSTRACT TRUNCATED AT 250 WORDS)     

Ontogeny of the GTP-Binding Protein Go in Rat Brain and Heart

We determined the ontogeny of the GTP-binding protein Go in rat brain and heart by employing highly sensitive enzyme immunoassay methods. In the brain, the alpha subunit of Go (Go alpha) gradually increased and reached adult levels approximately 20 and 30 days after birth in cerebral cortex and cerebellum, respectively. Concentrations of beta subunits, which were also quantified by the immunoassay, were almost equal to those of Go alpha in the brain of rats younger than 10 days, but were higher than those of Go alpha after 10 days. These results suggest that late development of GTP-binding proteins other than Go. Go alpha was immunohistochemically positive in neuropils and negative in cell bodies at any age tested. In the heart, the concentrations of Go alpha increased up to several times of the adult level just after birth, and then gradually decreased after the 20th postnatal day. The level of Go alpha in the liver, however, was very low and constant throughout ontogenic development. An immunohistochemical study indicated that Go alpha was positive in the cardiac muscle of young rat, but negative in that of adult rat. These results indicate that Go alpha exists in cells other than those of nervous tissues and neuroendocrine cells in some periods of ontogenic development.     

Studies on oxygen and volume restrictions in cultured cardiac cells I. A model for ischemia and anoxia with a new approach

Summary A novel incubation unit is described that is highly suitable for thorough studies of oxygen deprivation states. Its application with cultured heart cells is experimentally demonstrated. The release of enzymes, taken as a marker for cell damage, has clearly shown that restriction of the volume of extracellular medium combined with oxygen plus glucose deprivation caused greatest cellular damage. It may be considered as an experimental ischemia-like state. Furthermore, the onset of cellular damage followed a time table very much like that occurring in vivo under similar conditions, more so than any other previously described studies. A time lag between the release of cytoplasmic enzymes and lysosomal enzymes and other observations made in the present study suggests a sequential order of events in which the release of cytoplasmic enzymes occurs at a stage of reversible damage due to oxygen deprivation, whereas the release of lysosomal enzymes may point at irrepairable damage. Supported by grants from The Chief Scientist, Ministry of Health, State of Israel; The Ministry of Education and Sciences, State of Niedersachsen (FRG); and The Foundation for Heart Research from Mr. and Mrs. D. Vidal-Madjar, Paris, France. This study was done as partial fulfilment of Vemuri's Ph.D. thesis in biochemistry.