OBSERVATIONS ON PLASTID FINE-STRUCTURE IN THE HOLOPARASITIC ANGIOSPERM EPIFAGUS VIRGINIANA

The ultrastructure of plastids in cortex and phloem parenchyma cells of Epifagus virginiana (L.) Bart. is described. Based upon morphology and content, several distinct plastid types appear to exist. “Tubular” complexes, lipid globules and electron dense inclusions in different arrangements appear to account for the degree of plastid variability. When results obtained with Epifagus are compared with those obtained by others for a closely related genus, a striking parallel is shown to exist.     

Melatonin as antioxidant, geroprotector and anticarcinogen

The effect of the pineal indole hormone melatonin on the life span of mice, rats and fruit flies has been studied using various approaches. It has been observed that in female CBA, SHR, SAM and transgenic HER-2/neu mice long-term administration of melatonin was followed by an increase in the mean life span. In rats, melatonin treatment increased survival of male and female rats. In D. melanogaster, supplementation of melatonin to nutrient medium during developmental stages produced contradictory results, but and increase in the longevity of fruit flies has been observed when melatonin was added to food throughout the life span. In mice and rats, melatonin is a potent antioxidant both in vitro and in vivo. Melatonin alone turned out neither toxic nor mutagenic in the Ames test and revealed clastogenic activity at high concentration in the COMET assay. Melatonin has inhibited mutagenesis and clastogenic effect of a number of indirect chemical mutagens. Melatonin inhibits the development of spontaneous and 7-12-dimethlbenz(a)anthracene (DMBA)- or N-nitrosomethylurea-induced mammary carcinogenesis in rodents; colon carcinogenesis induced by 1,2-dimethylhydrazine in rats, N-diethylnitrosamine-induced hepatocarcinogenesis in rats, DMBA-induced carcinogenesis of the uterine cervix and vagina in mice; benzo(a)pyrene-induced soft tissue carcinogenesis and lung carcinogenesis induced by urethan in mice. To identify molecular events regulated by melatonin, gene expression profiles were studied in the heart and brain of melatonin-treated CBA mice using cDNA gene expression arrays (15,247 and 16,897 cDNA clone sets, respectively). It was shown that genes controlling the cell cycle, cell/organism defense, protein expression and transport are the primary effectors for melatonin. Melatonin also increased the expression of some mitochondrial genes (16S, cytochrome c oxidases 1 and 3 (COX1 and COX3), and NADH dehydrogenases 1 and 4 (ND1 and ND4)), which agrees with its ability to inhibit free radical processes. Of great interest is the effect of melatonin upon the expression of a large number of genes related to calcium exchange, such as Cul5, Dcamkl1 and Kcnn4; a significant effect of melatonin on the expression of some oncogenesis-related genes was also detected. Thus, we believe that melatonin may be used for the prevention of premature aging and carcinogenesis.     

Features of gastrin reaction in rats with different susceptibilities to gastric mucosa lesions in immobilization-cold stress]

The connection between the character of gastrin and acid reactions and visible morphological changes of gastric mucosa in immobilising-cold stress was studied in the experiments on mongrel rats. It is established that in the rats the fundal gastric mucosa is resistant to the disturbing action of the immobilising-cold stress. The post-stress gastrin contents in the antrum and duodenum mucosa is higher and in the serum lower than in rats with ulceration. The rats with the stress erosions have the intermediate position. The acid factor didn't play the significant role in the ulcerogenesis because its value didn't overstep the limits established in the extradigestive period.     

Energy metabolism and myocardial ultrastructure in autoimmune cardiomyopathy

Alterations in the heart energy metabolism, early defects in cardiomyocyte sarcolemma and heart resistance to ischemic damage have been investigated in experimental autoimmune cardiomyopathy. Systolic and diastolic pressures were registered and the speed of ischemic contracture development was determined on the isolated perfused rat hearts. Oxidative phosphorylation parameters, macroenergetic phosphate levels were determined. The ultrastructure and cell membrane permeability to lanthanum were studied. The results obtained have shown that the hearts of rats with autoimmune cardiomyopathy revealed decreased macroenergetic phosphate levels: ATP level was 22% lower and Pcr was 45% lower. Resistance of cardiomyopathic hearts to ischemic stress significantly reduced, cell membrane permeability was distorted. The above changes are believed to be due to incompetent myocardial hypertrophy and Ca overload.     

Whole-cell currents in macrophages: II. Alveolar macrophages

Summary Although an outwardly rectifying K⁺-conductance has been described in murine peritoneal macrophages and a murine macrophage cell line, the expression of this conductance in human monocyte-derived macrophages (HMDMs) is rare. Whole-cell current recordings in this study were obtained from HMDMs differentiated in adherent culture for varying periods of time following isolation and compared to currents obtained in human alveolar macrophages (HAMs) obtained from bronchoalveolar lavage. These studies were undertaken to compare ionic current expression in the in vitro differentiated macrophage to that of a human tissue macrophage. HAMs are the major population of immune and inflammatory cells in the normal lung and are the most readily available source of human tissue macrophages. Of the 974 HMDMs in the study obtained from a total of 36 donors, we were able to observe the presence of the inactivating outward current (I _A ) which exhibited voltage-dependent availability in only 49 (or 5%) of the cells. In contrast, whole-cell current recordings from HAMs, revealed a significantly higher frequency ofI _A expression (50% in a total of 160 cells from 26 donors). In the alveolar cell, there was no correlation observed between cell size and peakI _A amplitude, nor was there a relationship between peakI _A amplitude and time in culture. The current in both cell types was K⁺ selective and 4-aminopyridine (4-AP) sensitive.I _A in both cell types inactivated with a time course which was weakly voltage-dependent and which exhibited a time constant of recovery from inactivation of approximately 30 sec. The time course of current inactivation was dependent upon the external K⁺ concentration. An increase in the time constant describing current decay was observed in elevated K⁺. Current activation was half-maximal at approximately –18 mV in normal bathing solution. Steady-state inactivation was half-maximal at approximately –44 mV. The presence of the outwardly rectifying K⁺ conductance may alter the potential of the mononuclear phagocyte to respond to extracellular signals mediating chemotaxis, phagocytosis, and tumoricidal functions.     

Triacylglycerol content,productivity and fatty acid profile in Scenedesmus acutus PVUW12

A detailed lipid characterization of Scenedesmus acutus PVUW12, with emphasis on the evaluation of triacylglycerols (TAGs) as a biodiesel feedstock, is presented. When algal cells were grown in nitrogen-free medium (N stress), a lipid increase was detected that was mainly due to TAG accumulation. In situ fluorescence measurements allowed the kinetics and extent of neutral lipid accumulation to be followed. Under N stress, the productivity of total lipids and TAGs increased significantly (80.99 and 63.74 mg L^?1 day^?1, respectively) compared with controls (29.51 and 16.23 mg L^?1 day^?1, respectively). Monounsaturated fatty acids were the major fraction and increased further (49.74 %) in stressed cells, with oleic acid as the most abundant compound (46.97 %). The polyunsaturated fatty acid composition of this algal oil appears to meet the European Standard EN 14214. These results indicate that S. acutus oil meets the requirements for its use as a biodiesel feedstock. Since this strain was also proposed for wastewater bioremediation, this opens up the possibility of its use in an integrated system combined with biofuel production.     

Sampling Rhyparida nitida Clark (Coleoptera: Chrysomelidae) and symptoms of their damage on sugarcane

Sampling statistics were determined for larvae, pupae and adults of the chrysomelid Rhyparida nitida associated with sugarcane in Australia and for symptoms of their damage. Iwao's patchiness regression was inappropriate for modelling the mean–variance relationships of the insect counts. Taylor's power law was used to model these data and relationships were developed for counts of small, medium and large larvae, all larvae combined, pupae and adults. The mean–variance relationships of counts of live shoots and shoots killed by larvae of R. nitida were modelled using Iwao's patchiness regression; Taylor's power law was not appropriate to either data set. Relationships to determine sample sizes for fixed levels of precision and fixed-precision-level stop lines for sequential sampling of the different stages and live and dead shoots were also developed. Neither the ln(x + 1) transformation nor the Healy and Taylor transformation consistently standardised the mean–variance relationships of insect counts and the appropriate transformation should be selected on a case-by-case basis. Counts of both live and dead shoots were adequately transformed by the Iwao and Kuno transformation.     

Characterization and modeling of monocyte-derived macrophages after spinal cord injury

Spinal cord injury (SCI) elicits a neuroinflammatory reaction dominated by microglia and monocyte-derived macrophages (MDM). Because MDM do not infiltrate the spinal cord until days after injury, it may be possible to control whether they differentiate into neuroprotective or neurotoxic effector cells. However, doing so will require better understanding of the factors controlling MDM differentiation and activation. Our goal was to develop an in vitro model of MDM that is relevant in the context of SCI. This tool would allow future studies to define mechanisms and intracellular signaling pathways that are associated with MDM-mediated neuroprotection or neurotoxicity. We first characterized SCI-induced cytokine expression in MDM using laser capture microdissection and real-time PCR. Based on this data, we assessed which easily procurable primary macrophage subset would mimic this phenotype in vitro. We established the baseline and inductive potential of resident peritoneal, thioglycollate-elicited peritoneal and bone marrow-derived macrophages (BMDM) at the molecular, cellular and functional level. Of these cells, only BMDM retained the phenotypic, molecular and functional characteristics of MDM that infiltrate the injured spinal cord. Thus, peripheral macrophages should not be used interchangeably in vitro to model the functional consequences of the MDM response elicited by SCI.