Binding of Radioactively Labelled Concanavalin A and Wheat Germ Agglutinin to Normal and Virus-transformed Cells

VARIOUS substances isolated from plants cause animal cells to clump. Several of these lectins¹ preferentially agglutinate cells which have been transformed spontaneously or by chemicals or viruses^2–7. The best known lectins of this class are concanavalin A (Con A) isolated from jack beans⁸ and wheat germ agglutinin⁴, which seem to bind to carbohydrate groups on the cell surface. The determinants recognized by the lectins seem to be N-acetyl-D-glucosamine for WGA⁴ and probably α-methyl-D-glucopyranoside for Con A⁶.     

Distribution and incidence of yellowing viruses in sugar beet crops in Spain from 1990 to 1993

Surveys of the principal yellowing viruses of sugar beet, beet yellows virus (BYV) and beet mild yellowing virus (BMYV) in Spain were carried out from 1990–1993. Beet yellowing viruses were detected in all provinces, although the mean percentages of plants infected with BYV and BMYV were practically zero in the southern zone. Within the northern zone high variations from one province to another could be observed. The mean percentages of plants infected with BYV were higher in the Ebro Valley than in the Duero Valley. Areas infected with BYV were very restricted, while BMYV could be found to a variable extent all over Spain, although the infection levels were lower. The incidence and distribution of these viruses in the Spanish sugar beet crop makes the study and application of control measures for beet yellowing viruses necessary.     

Production of a stream shredder, Peltoperla maria (Plecoptera: Peltoperlidae) in disturbed and undisturbed hardwood catchments

SUMMARY. (1) The average benthic density of Peltoperla maria in an undisturbed southern Appalachian stream was more than twice that of a nearby stream draining a previously clear-cul catchment in its tenth year of natural secondary succession.
(2) Peltoperla production estimates, using three methods, do not show a significant difference in production between streams draining the two catchments. We attribute these results to quicker growth and slightly higher densities of larger nymphs in the disturbed stream. Production estimates for the disturbed stream ranged from 498 to 560 mg (ash free dry weight) m⁻²y⁻¹ while those for the undisturbed stream were 41–4–515 mg m⁻² y⁻¹.
(3) Our results reinforce the view that conclusions based solely upon numerical densities may lead to erroneus interpretations about the roles organisms play in ecosystems.
(4) Annual frass production by this shredder is about 20 times (10 g m⁻² y⁻¹) the secondary production of P. maria.     

Phenylalanine ammonia-lyase activity in callus cultures of Pinus elliotii

Phenylalanine ammonia-lyase (PAL) activity increased 8- to 12-fold in pine (Pinus elliotii Engelm.) callus tissue within 2 days after subculturing on fresh medium. Factors such as increasing the sucrose content of the media, imposing additional tissue in jury or subculturing more frequently did not cause additional stimulation of PAL activity. The rapid increase in PAL activity appeared to be due to enzyme activation, since cycloheximide did not appreciably reduce the stimulation of PAL activity. The subsequent loss of increased PAL activity with age was reduced by cycloheximide and a cool growth environment.     

中哈边境蝗区蝗虫孳生和发生地的重要生态学特征

中哈边境蝗虫跨境迁飞为害常造成严重损失,明确蝗虫迁出和迁入区生态条件异同是提高监测预警水平的基础。本研究采用野外调查与室内分析相结合的方法,比较了中国新疆塔城边境蝗区和哈萨克斯坦境内阿拉湖蝗区生态特征的异同。研究发现,塔城边境与阿拉湖蝗区地势平坦,平均海拔无明显差异;两蝗区主要植被和蝗虫群落结构相似;阿拉湖蝗区土壤的p H值、含盐量、有机质含量均显著低于塔城边境蝗区;除Ca~(2+)和CO_3~(2-)外,阿拉湖蝗区土壤中Cl~-、SO_4~(2-)、K~+、Na~+、Mg~(2+)、HCO_3~-含量均明显低于塔城边境蝗区;两蝗区20a(1980-1999年)年均气温和降水量无差异显著,而年、季节平均气温和降水量5 a滑动趋势差异显著。哈萨克斯坦境内阿拉湖蝗区的植被种类、较低的土壤p H值和含盐量及有机质、季节的温度和降水量均适合蝗虫产卵,是蝗虫的重要孳生地;我国境内塔城边境蝗区内大面积撂荒地增加了适宜蝗虫发生的环境。中哈边境蝗区生态条件的相似性和差异性表明蝗虫跨境为害仍将是塔城边境蝗灾发生的重要特点,研究结果对于指导中哈边境蝗区的监测和防控有重要作用。     

European checkerspots (Melitaeini: Lepidoptera,Nymphalidae) are not aposematic – the point of view of great tits (Parus major)

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Characterization of polymorphic microsatellite loci for the polychaete tubeworm Hobsonia florida

Eight dinucleotide microsatellite loci were isolated and characterized from Hobsonia florida, a tube‐dwelling ampharetid polychaete. The identified loci were highly polymorphic, with allelic diversity ranging from six to 11 alleles. Levels of expected heterozygosity were 0.52 or greater in all cases, averaging 0.78 across the complete set of loci. Cross‐species amplification was successful in three of the eight loci for one or both of the other species (Melinna cristata and Ampharete acutifrons) tested. Although these novel loci were designed for immediate utility in H. florida population‐level research, these results indicate they may prove useful in studies of other related taxa.     

Acanthamoeba comandoni and A. astronyxis: Taxonomic Characteristics of Mitotic Nuclei, "Centrosomes" and Cysts

SYNOPSIS. A new strain (F-111) of Acanthamoeba comandoni was isolated from Turtle Pond, Boston, Mass. Comparative studies of A. comandoni Pussard, 1964 and A. astronyxis Ray & Hayes, 1954 indicated that the 2 species are distinct, and that the 2 names are valid and not synonymous as proposed by various investigators. An astral or brush-pile “centrosomal body” was present near the nucleus of interphase stages of both species. During mitosis, bipolar “centrosomal bodies” were detected in A. comandoni but not in A. astronyxis. Cysts of both species were spherical and had stellate or rayed endocysts. The rays in cysts of A. comandoni extended outward and upward at different angles, and all of them were not visible in the same optical plane. In A. astronyxis, the rays extended outward from the central cyst mass, and all of them were visible in the same optical plane.