Litter production and decomposition in a terra-firme forest of Central Amazonia

Summary Chemical and biological aspects of litter production and decomposition were studied in three distinct areas of the Central Amazon. Litter production was measured during three years, employing the litter trap technique, with adapted conical collectors. Leaf litter decomposition was studied in experiments, over five-month-periods with repetitions for the dry and wet seasons, using the nylon-mesh bag technique. The greatest litter production took place during the drier period of the year, mainly from June to October, while decomposition processes were more accentuated in the wet season: in the plateau site, one-half, of the litter disappears, according to a mathematical model, in about, 218 days under dry season conditions as against 32 days in the wet season. In the rainy season, weight reduction and mineral losses from decomposing leaves occurred more rapidly, owing to the intense biological activity on the material during this period. Particularly noticeable was the intense activity of termites in organic matter breakdown and mineral removal, and the extensive root penetration in the decomposing leaves, which removed some minerals but increased the amounts of other. Leaching effects were also quite noticeable in this period. During the rainy season, in the latosol sites, termites were responsible for more than 40% of the removal of decomposing leaves. While intense biological activity appears to be the major factor responsible for weight reduction and loss of many minerals, as well as for the accumulation of some other minerals (mainly zinc iron and aluminium) in the decomposing material, leaching seems to be the major factor responsible for the loss of certain minerals such as potassium, boron and copper.     

Electron microscopy of mitochondrial DNA in Podospora anserina and the presence of a multimeric range of circular DNA molecules from senescent cultures]

Mitochondrial DNA from young cultures of race s of Podospora anserina was isolated. Its density in Cesium chloride density equilibrium gradients was 1.694 g/cc. Examination by the electron microscope revealed that ca 1% of this DNA consisted of circles, 31 micrometer in contour length; the remaining DNA was composed of linear molecules ranging in length from 2 to 33 micrometer. In DNA of similar density obtained from senescent cultures of the same race s, about 11% of the molecules consisted of a multimeric set of circles ranging in size from 0.9 to 15 micrometer, with most being in the 1.8 and 2.7 micrometer classes. The similarity of these DNA molecules with the mitochondrial DNA from rho(-) yeast mutants is discussed.     

Identification of intracellular particles of pesticides in ciliate protozoa by Raman microprobe

Summary A Raman microprobe technique was used for the identification of intracellular particles of a pesticide added to a culture of the ciliate protozoanColpidium campylum. 2 methods, a wet and a dry, can be used for sample preparation. In both cases it was possible to find characteristic lines of 2 pollutants: 4,4-dichlorodiphenyl and-endosulfan. Some technical problems were encountered: the dry method causes drastic cellular alteration; the cell can move and go out of laser focus in the wet method.     

Baker's yeast,an attractant for baiting traps for Chagas' disease vectors

We tested the attraction of volatile compounds, produced by the aerobic growth ofSaccharomyces cerevisiae on saccharose forTriatoma infestans. For these tests, we exploited the behavioural characteristic of these haematophagous insects of dropping when searching for food. In olfactometer assays, yeast cultures activated and attracted bugs as effectively as a mouse. The attraction of the cultures was significantly reduced when the carbon dioxide released was partially eliminated using potassium hydroxide. Yeast cultures were also tested as lures in a novel trap device. A baited device for trapping Chagas' disease vectors using the behavioural peculiarities ofT. infestans and this simple attractant is described.     

干湿法联合制备水煤浆技术的研究

针对国内当前水煤浆生产和销售实际情况,为给远离水煤浆厂且自身不具备建厂能力的众多中小型水煤浆用户群和原煤产地间提供一条切实可行的工艺途径,提出将干湿法联合制浆工艺应用到工业生产的可行性。本文以内蒙古鄂尔多斯煤（不粘煤）为原料,在此工艺方法下确立了合适于制浆用煤的级配比例和相应的药剂用量,大幅度降低了水煤浆的运输成本,并得到了最佳煤粉级配比例。     

Inhibition ofSaccharomyces cerevisiae division by 5-trifluoro-methyl-6-azauracil

Summary Cell division, as studied in asynchronous cultures of yeast cells, is sensitive to 5-trifluoromethyl-6-azauracil (F₃CAzU). Under defined conditions (10 mmoles l^–1 F₃CAzU) this compound blocks immediately and completely the process of cell division. Using synchronized cells, the time-point at which division process of yeast cell can be inhibited by F₃CAzU has been determined. The inhibitor effect of this compound is completely reversed by thymine, thymidine and uracil.     

Plants as a direct source of fuel

Summary Euphorbia lathyris, a plant which has been proposed as an energy farm candidate yields a total of 35% of its dry weight as simple organic extractables. Chemical analyses of the extracts show that 5% of the dry weight is a mixture of reduced terpenoids, in the form of triterpenoids, and 20% of the dry weight is simple sugars in the form of hexoses. The terpenoids can be converted to a gasoline-like substance and the sugars can be fermented to alcohol. Based on a biomass yield of about 25 dry tons ha^–1 year^–1, the total energy that can be obtained from this plant in the form of liquid fuels is 48 MJ ha^–1 year^–1, 26 MJ in the form of hydrocarbons and 22 MJ in the form of ethanol. A conceptual process study for the large scale recovery ofEuphorbia lathyris products indicates that this crop is a net energy producer. Several lines of investigation have been started to increase the hydrocarbon yield of this plant. Tissue cultures ofE. lathyris have been established and will be used for selection, with the aim of regenerating a superior plant. Biochemical studies have been initiated to elucidate regulation of terpenoid metabolism. Future plans include eventual genetic engineering to select the most desirable plant for hydrocarbon production.This work was supported by the Assistant Secretary for Conservation and Solar Energy, Office of Solar Energy, Solar Applications for Industry Division of the US Department of Energy under Contract No. W-7405-ENG-48.     

Quantitation of proliferative mucosal cells of the Mongolian gerbil on a weight basis

Summary Quantitation of proliferative activity of the intestine of the gerbil shows a substantial decrease in proliferative activity as compared to the mouse. The use of dry vs wet weights proved to have no bearing on calculations of proliferative activity. The gerbil may prove a useful model for drug and radiation experimentation.This work was supported by National Science Foundation grant No. GB35522. Reprint requests should be addressed to: H.S., Health Physics, Merck Sharp & Dohme Research Laboratories, West Point (Pennsylvania 19486, USA).     

Tuber formation and protein content in some wild cassava (Mandioca) species native of central Brazil

Summary Screening for protein content in some wild species of Manihot showed 2 of them to have a notably high percentage of protein on dry matter basis. Moreover, one of these high-protein wild species was found to be extremely sweet.This work is being carried out with the aid of a grant from the International Development Research Centre, Ottawa, Canada.     

Action de la castration partielle ou totale sur la croissance et le fonctionnement de l'appareil génital chez le planorbeBiomphalaria glabrata (gastéropode pulmoné)

Summary Total castration increases the weight, delays oviposition and reduces the functioning of the genital organs but partial gonadectomy has no effect. After partial castration, the ovotestis does not regenerate. Partial or total castration has no effect on the wet and dry weight of the genital tracts.     

Zum Geschmackssinn der Baumwollwanze (Dysdercus intermedius)

Summary The bugDysdercus intermedius has gustatory receptors on the terminal segments of its antennae. Thirsty bugs discriminate between dry and wet cellulose swabs: only if they are stimulated with moist swabs, do they extend the proboscis. The stimulating effectiveness of different mono-, oligosaccharides and glycosides was studied by touching the antennae of hungry bugs and observing the extension of the proboscis. The result, that fructose is completely ineffective, entitles one to the assumption that the sugar receptor cells ofDysdercus possess neither a 1C site nor a furanose site.     

Effects of acid deposition on crops and forests

Summary Acid deposition includes the gases, sulphur dioxide and nitrogen oxides, and their derivative acids which are dissolved in various forms of precipitation. The effects of both dry and wet deposition on crops and forests are reviewed, including interactions between these two categories of pollutant. Particular emphasis is given to the current forest decline in central Europe, including the possible role of ozone.     

Neutron activation analysis of saliva from the tickAmblyomma variegatum

Summary The hygroscopic saliva produced by fastingAmblyomma variegatum adults during prolonged exposure to dry air was found to contain sodium, potassium and chlorine in molar proportions of 1.1–1.7–3.8 respectively, or proportions by dry weight of 8, 21 and 41%. These values are quite different from those reported previously for saliva from recently fed ixodid ticks. TheA. variegatum saliva contained, by dry weight, less than 5% sulphur and less than 1.5% each of phosphorus, calcium, magnesium and iron.Acknowledgments. I wish to thank Prof. W. Knülle for extending to me support granted by the Deutsche Forschungsgemeinschaft, and Dr D. Rudolph for providing the saliva solids.     

Lethal effects of heat on bacterial physiology and structure

High temperatures have profound effects on the structural and physiological properties of sporulating and non-sporulating bacteria, with membranes, RNA, DNA, ribosomes, protein and enzymes all affected. Nevertheless, it is apparent that no one single event is responsible for cell death. The induction of intracellular heat-shock proteins and the activation of extracellular alarmones in vegetative cells exposed to mildly lethal temperatures are important cell responses. In bacterial spores, several factors contribute to the overall resistance to moist (wet) and dry heat; the latter, but not the former, induces mutations. Heat resistance develops during sporulation, when spore-specific heat-shock proteins are also produced. Heat sensitivity is regained during germination of spores.     

Ydc1p ceramidase triggers organelle fragmentation, apoptosis and accelerated ageing in yeast

Saccharomyces cerevisiae dihydroceramidase Ydc1p hydrolyzes ceramide, resulting in accumulation of free long-chain bases and their phosphates. Yeast mutants lacking YDC1 are characterized by increased chronological lifespan. Moreover, we found YDC1 up-regulated in a yeast mutant displaying reduced chronological lifespan. These data suggest an important role for Ydc1p in chronological lifespan determination in yeast. Mitochondria are known to play an important role in chronological lifespan and apoptosis. In this study we demonstrated that overexpression of YDC1 results in reduced chronological lifespan and increased apoptotic cell death. We found YDC1 overexpression to result in mitochondrial fragmentation and dysfunction. Interestingly, vacuoles also appeared to be fragmented and dysfunctional upon YDC1 overexpressing. Exogenous addition of ceramide to YDC1-overexpressing cultures increased chronological lifespan and restored organelle function. In conclusion, this study describes a direct link between ceramide metabolism in yeast and mitochondrial and vacuolar fragmentation and function, with consequences for chronological lifespan in yeast.     

Der Hyaluronsäuregehalt und die «Hyaluronidase»-Aktivität der Leukozyten

Summary The hyaluronic acid content of leucocytes from the peritoneum of rats shows a significant concentration when measured either turbidimetrically or oxydimetrically, the average value calculated for wet weight being 0.7–0.8%. The hyaluronic acid break down capacity of the leucocytes is not a specific enzyme action but can be attributed to their high ascorbic acid content. The phenomenon has no well defined pH or temperature optimum and can be inhibited by oxine and by semicarbazide.     

Effect of administration of estrogen to pregnant rabbits on the lipid content and composition of the fetal brain

Summary Intramuscular injection of 17 -estradiol to pregnant rabbits did not produce any significant change in the phospholipid, neutral lipid and cholesterol content of the fetal brains, nor did it cause any significant difference in their wet and dry weights. It may be inferred that use of estrogen in the gestational period to enhance surfactant production and lung maturation in the fetus would not produce adverse effects on the fetal brain lipids.     

Ascorbic acid content of neotropical plant parts available to wild monkeys and bats

The ascorbic acid content of foliage available to wild primates and bats in Panama (in transition between wet and dry seasons) was lower than that of temperate zone foliage but higher than that of most fruits and vegetables. Intakes of ascorbic acid (mg/kg b.wt/day) by wild primates and frugivorous bats in Panama are much greater than that of most human populations.     

Histochemischer Nachweis der im Zytoplasma regenerativ nach P-Mangelzüchtung auftretenden phosphatischen Überkompensation

Summary It was established by histochemical method that the regeneration of phosphorus-starved yeast, in comparison with normal yeast, is accompanied by a phosphatic over-compensation. This also provides a striking criterion for the evaluation of the cellular phosphate metabolism.Inspite of the considerably higher total-P-contents, if regenerated phosphorus-starved yeast, it contains almost the same quantity of nucleic acids as normal yeast.     

Ascorbic acid content of neotropical plant parts available to wild monkeys and bats

Summary The ascorbic acid content of foliage available to wild primates and bats in Panama (in transition between wet and dry seasons) was lower than that of temperate zone foliage but higher than that of most fruits and vegetables. Intakes of ascorbic acid (mg/kg b.wt/day) by wild primates and frugivorous bats in Panama are much greater than that of most human populations.