Geographical variation in encapsulation ability ofDrosophila melanogaster larvae and evidence for parasitoid-specific components

Summary The ability ofDrosophila melanogaster larvae in Europe to encapsulate the eggs of their most important parasitoids,Asobara tabida andLeptopilina boulardi, shows a large amount of geographical variation. Interestingly, encapsulation ability againstA. tabida is not correlated with encapsulation ability againstL. boulardi. This indicates that the encapsulation system ofD. melanogaster larvae has parasitoid-specific components. The variation in encapsulation ability can only partly be explained by the incidence of parasitism on the larvae. This means that factors other than the two parasitoid species must be selection pressures on the encapsulation ability ofD. melanogaster larvae.     

EineAnabaena-artige Cyanophycee mit auffallendem Zellteilungs- und Fadenzerfallsrhythmus

This paper deals with a filamentousCyanophycea from aSphagnum bog whose position in the current system is dubious. A characteristic feature, among others, is a certain rhythm of cell division and bipartition of the filaments. As a consequence, only 8-, 16- and 32-celled filaments are present in the population. An occasional disturbance of the rhythm is transitory. In the longitudinal direction the filaments exhibit mirror symmetry in regard to their middle.

     

毛茛科五新种

描述了毛茛科五新种:(1)托里乌头,与阿尔泰乌头近缘,区别为其茎和叶无毛,总状花序极密集,雄蕊花丝多有1或2小齿。(2)门源翠雀花,与大通翠雀花近缘,区别为其茎极短,花序总状,退化雄蕊瓣片不分裂。(3)云台山铁线莲,与裂叶铁线莲近缘,区别为其叶为二回羽状复叶,花较小,雄蕊花丝呈黑色,无脉。(4)黑丝铁线莲,与前种云台铁线莲在亲缘关系上极为相近,区别为其小叶较小,多呈狭卵形或披针形,聚伞花序也较小,通常只具3花。(5)五台山毛茛,与砾地毛茛相似,区别为其基生叶被柔毛,花瓣蜜槽具鳞片,心皮具短而粗的花柱和小柱头。     

Variation in encapsulation sensitivity of Cotesia sesamiae biotypes to Busseola fusca

Many braconid wasp species inject polydnaviruses to overcome their host's immune system. In the species Cotesia sesamiae, two biotypes exist that differ in their ability to develop in the host Busseola fusca. The biotype from coastal Kenya is infected with Wolbachia and is not able to develop in larvae of B. fusca, whereas the uninfected inland biotype of this wasp can develop in B. fusca. The genetic transmission of the developmental ability was studied through a series of genetic crosses and superparasitization experiments. The Wolbachia infection of the coastal type did not play a role in the encapsulation response of the host. Experiments show that the polydnaviruses of the wasps could not prevent the encapsulation of the coastal parasitoid eggs. Most likely, larval characteristics such as surface proteins played a more important role in the encapsulation response of the host even in the presence of a functional polydnavirus.     

Social encapsulation of the small hive beetle (<Emphasis Type="Italic">Aethina tumida</Emphasis> Murray) by European honeybees (<Emphasis Type="Italic">Apis mellifera</Emphasis> L.)

Summary European and African subspecies of honeybees (Apis mellifera L.) utilize social encapsulation to contain the small hive beetle (Aethina tumida Murray), a honeybee colony scavenger. Using social encapsulation, African honeybees successfully limit beetle reproduction that can devastate host colonies. In sharp contrast, European honeybees often fail to contain beetles, possibly because their social encapsulation skills may be less developed than those of African honeybees. In this study, we quantify beetle and European honeybee behaviours associated with social encapsulation, describe colony and time (morning and evening) differences in these behaviours (to identify possible circadian rhythms), and detail intra-colonial, encapsulated beetle distributions. The data help explain the susceptibility of European honeybees to depredation by small hive beetles. There were significant colony differences in a number of social encapsulation behaviours (the number of beetle prisons and beetles per prison, and the proportion of prison guard bees biting at encapsulated beetles) suggesting that successful encapsulation of beetles by European bees varies between colonies. We also found evidence for the existence of circadian rhythms in small hive beetles, as they were more active in the evening rather than morning. In response to increased beetle activity during the evening, there was an increase in the number of prison guard bees during evening. Additionally, the bees successfully kept most (~93%) beetles out of the combs at all times, suggesting that social encapsulation by European honeybees is sufficient to control small populations of beetles (as seen in this study) but may ultimately fail if beetle populations are high.Received 20 January 2003; revised 21 April 2003; accepted 29 April 2003.     

Regulation of nitrogenase levels in Anabaena sp. ATCC 33047 and other filamentous cyanobacteria

Incubation in the dark of photoautotrophically grown N₂-fixing heterocystous cyanobacteria leads to a loss of nitrogenase activity. Original levels of nitrogenase activity are rapidly regained upon re-illumination of the filaments, in a process dependent on de novo protein synthesis. Ammonia, acting indirectly through some of its metabolic derivatives, inhibits the light-promoted development of nitrogenase activity in filaments of Anabaena sp. ATCC 33047 and several other cyanobacteria containing mature heterocysts. The ammonia-mediated control system is also operative in N₂-fixing filaments in the absence of any added source of combined nitrogen, with the ammonia resulting from N₂-fixation already partially inhibiting full expression of nitrogenase. High nitrogenase levels, about two-fold higher than those in normal N₂-fixing Anabaena sp. ATCC 33047, are found in cell suspensions which have been treated with the glutamine synthetase inhibitor l-methionine-d,l-sulfoximine or subjected to nitrogen starvation. Filaments treated in either way are insensitive to the ammonia-promoted inhibition of nitrogenase development, although this insensitivity is only transitory for the nitrogen-starved filaments, which become ammonia-sensitive once they regain their normal nitrogen status.Abbreviations Chl chlorophyll - EDTA ethylenediaminetetraacetic acid - MSX l-methionine-d,l-sulfoximine     

毛茛科六新种

该文描述了毛茛科六新种：(1)托里乌头,与阿尔泰乌头近缘,区别为其茎和叶无毛,总状花序极密集,雄蕊花丝多有1或2小齿。(2)门源翠雀花,与大通翠雀花近缘,区别为其茎极短,花序总状,退化雄蕊瓣片不分裂。(3)云台山铁线莲,与裂叶铁线莲近缘,区别为其叶为二回羽状复叶,花较小,雄蕊花丝呈黑色,无脉。(4)黑丝铁线莲,与前种云台山铁线莲在亲缘关系上极为相近,区别为其小叶较小,多呈狭卵形或披针形,聚伞花序也较小,通常只具3花。(5)五台山毛茛,与砾地毛茛相似,区别为其基生叶被柔毛,花瓣蜜槽具鳞片,心皮具短而粗的花柱和小柱头。(6)靖西铁线莲,与宝岛铁线莲在亲缘关系上接近,区别为其茎疏被短柔毛,小叶卵形或狭卵形,不分裂,聚伞花序有1~3花,萼片较大(长1.7~2 cm,宽0.5~0.7 cm)。     

A new species of Acanthosyris (Santalaceae) from Bolivia and a key to the woody South American Santalaceae

Acanthosyris asipapote, a new species from the vicinity of Santa Cruz, Bolivia, is described and illustrated. It is most similar to A. paulo-alvinii Barroso, known only from the state of Bahia, Brazil, but differs by leaf characters, pilose filaments, and smaller seeds. A key to the five woody genera and nine species of Santalaceae in South America is provided. Cervantesia, Jodina, and Myoschilos are probably monotypic; Santalum (in South America) has a single species, and Acanthosyris has five species.     

Encapsulation and hemocyte numbers in three lepidopteran stemborers parasitized by Cotesia flavipes-complex endoparasitoids

Determination of the potential and actual host range of a natural enemy is crucial before its importation and release for biological control. We studied some of the factors that are important in determining the physiological host range of insect parasitoids attacking lepidopteran hosts. Our experimental system consisted of novel host-parasitoid associations, with two New World pyralid stalk borers, Diatraea saccharalis and D. grandiosella; one Old World crambid borer, Ostrinia nubilalis as hosts; and three Old World microgastrine braconids, Cotesia chilonis, C. sesamiae, and C. flavipes as parasitoids. Experiments on the chronology of encapsulation of the parasitoid progeny by host hemocytes indicated that lepidopteran stemborers that are taxonomically, behaviorally and ecologically very similar differ in their ability to encapsulate a parasitoid species. D. saccharalis encapsulated C. flavipes sometimes, whereas D. grandiosella consistently encapsulated C. sesamiae and C. flavipes. C. chilonis was not encapsulated by either Diatraea host. If encapsulation occurred it did not start until four days after parasitization and continued during the following days. O. nubilalis was an unsuitable host for all three parasitoid species; parasitoid eggs were killed within 24 hours of parasitization. O. nubilalis had nearly twice as many hemocytes present in the hemolymph compared to the Diatraea species. In many of the host-parasitoid combinations, there was an initial increase of hemocyte number soon after parasitization, which was not due to mechanical damage at oviposition. There was no correlation between total numbers of hemocytes present in the host hemolymph and the observed encapsulation levels. By understanding the encapsulation response we may be able to make better predictions about the host range of a parasitoid species before its release as a biological control agent.     

下延叉蕨和芽胞叉蕨配子体发育的研究

利用光学显微镜详细观察了叉蕨属(Tectaria)下延叉蕨(Tectaria decurrens)和芽胞叉蕨(T.fauriei)的配子体发育过程,记录了配子体各发育阶段的特征。结果表明:(1)下延叉蕨和芽胞叉蕨的孢子均为单裂缝,具周壁,由周壁形成纹饰,孢子极面观椭圆形,赤道面观豆形或肾形。(2)孢子萌发方式为向心型。(3)原叶体发育方式为三叉蕨型。(4)成熟原叶体心脏形,两翼向斜上方扩展。(5)均具单细胞和多细胞毛状体,在丝状体或片状体阶段出现。研究认为,从配子体发育角度看,叉蕨属是较进化的陆生真蕨类;毛状体的类型、位置和出现时间等特征在叉蕨属种间存在差异,可作为该属种间分类的特征。     

Seasonal variations in the encapsulation of eggs of the encyrtid parasitoid Metaphycus stanleyi by the pyriform scale, Protopulvinaria pyriformis

Encapsulation of eggs of the introduced parasitoid Metaphycus stanleyi Compere (Hymenoptera: Encyrtidae) by the pyriform scale, Protopulvinaria pyriformis (Cockerell) (Homoptera: Coccidae) under both greenhouse and field conditions, at Bet Dagan, was found to occur almost all year round (1986–1988). However, encapsulation rates varied considerably during the different seasons and were correlated with the ambient temperatures. The rates of efficient encapsulation (i) in scales infesting Hedera helix and Schefflera arboricola under greenhouse conditions, were lowest during December to May (6–17%) and highest during July to September (78–100%); (ii) in scales infesting avocado in the orchard, were lowest during October to May (0–11%) and highest during June to August (54–57%). Under greenhouse conditions, encapsulation rates did not differ in scales grown on H. helix and on S. arboricola, but were significantly lower in scales grown on avocado. Encapsulation by scales infesting S. arboricola was more frequent at temperatures ranging from 20–28 °C, than from 7–23 °C.The increased resistance by encapsulation of P. pyriformis to successful parasitization by M. stanleyi during the summer, may account for the inability of the parasitoid to prevent the autumn and winter outbreaks of the pest.     

Critical studies on the sexuality of southern Argentinian Ericaceae

Summary The family Ericaceae is considered to be mostly hermaphroditic and only in a few cases unisexual or dioecious. Five Argentinian species (Gaultheria antarctica Hook, f., G. caespitosa P. et E., G. phillyreaefolia (Pers.) Sleumer, G. tenuifolia (Phil.) Sleumer and Pernettya insana (Molina) Gunckel), previously described as hermaphroditic, were found by us to have two types of flowers: female and male. Female flowers have both a rudimentary androecium with stamens, in which the anthers are small, collapsed and without pollen grains or are reduced to filaments only, and a perfect gynoecium with well-developed ovules filling the carpel locules. The stigma is expanded and of the wet, papillate type, with copious to slight secretion. The stigma protrudes above the anthers. Male flowers have a well-developed androecium included within the corolla and a reduced gynoecium. Anthers are as long as the filaments, except in G. caespitosa. Pollen is shed as tetrads which are 100% viable. Ovule development ranges from total absence, passing through aborted ovules of various sizes to apparently normal ones. Stigmata are neither expanded nor papillate, except in Pernettya insana. Only in two species do the style and stigma extend beyond the level of the anthers. Heterostyly does not occur in any of the five species studied. Functional dioecy thus characterizes the five species considered and is reported for the first time in the genus Gaultheria.     

Monitoring <Emphasis Type="Italic">ALS1</Emphasis> and <Emphasis Type="Italic">ALS3</Emphasis> Gene Expression During In Vitro <Emphasis Type="Italic">Candida albicans</Emphasis> Biofilm Formation Under Continuous Flow Conditions

ALS1 and ALS3 encode cell-surface associated glycoproteins that are considered to be important for Candida albicans biofilm formation. The main goal of the present study was to monitor ALS1 and ALS3 gene expression during C. albicans biofilm formation (on silicone) under continuous flow conditions, using the Centers for Disease Control biofilm reactor (CDC reactor). For ALS1, we found few changes in gene expression until later stages of biofilm formation (72 and 96 h) when this gene appeared to be downregulated relative to the gene expression level in the start culture. We observed an induction of ALS3 gene expression in the initial stages of biofilm formation (0.5, 1, and 6 h), whereas at later stages, this gene was also downregulated relative to the gene expression level in the start culture. We also found that biofilms of an als3/als3 deletion mutant contained less filaments at several time points (1, 6, 24, and 48 h), although filamentation as such was not affected in this strain. Together, our data indicate an important role for ALS3 in the early phases of biofilm formation in the CDC reactor, probably related to adhesion of filaments, while the role of ALS1 is less clear.     

Growth dynamics of non-toxic Pseudo-nitzschia delicatissima and toxic P. seriata (Bacillariophyceae) under simulated spring and summer photoperiods

Marine planktonic diatoms of the genus Pseudo-nitzschia Peragallo have been responsible for amnesic shellfish poisoning (ASP) events worldwide through the production of the neurotoxin domoic acid (DA). The appearance and toxicity of Pseudo-nitzschia species is variable throughout the year and potentially linked to changes in environmental parameters; many ASP events occur in relatively high latitudes where day length is particularly variable with season. In UK waters, shellfish monitoring has prevented any impact on human health but has led to long-term closures of fisheries, with severe economic consequences. Laboratory experiments on two Pseudo-nitzschia species typically found in Scottish West Coast waters during spring (short photoperiod (SP)) and summer (long photoperiod (LP)) conditions were conducted to determine the influence of photoperiod on their growth and toxicity. Results indicated that non-toxic P. delicatissima (Cleve) Heiden achieved a greater cell density under SP (9-h light:15-h dark (L:D) cycle). For toxin-producing P. seriata (Cleve) H. Peragallo, a LP (18-h L:6-h D cycle) resulted in an enhanced growth rate, cell yield and total toxin production, but it decreased the toxin production per cell. A better understanding of the response of Pseudo-nitzschia species to photoperiod and other foreseeable environmental variables may help predict the appearance of toxic strains.     

Morphology,biology, and systematics ofCryptochlora perforans (Chlorarachniophyta), a phagotrophic marine alga

The life cycle ofCryptochlora perforans is described under culture conditions, including the following stages: Naked and walled amoebae, cysts, coccoid, palmelloid and flagellate stages. Phagotrophy of living diatoms, movement and reproduction are documented. Amoebae ofCryptochlora are chemotactically attracted by damaged algal filaments, perforate and penetrate such filaments, and subsequently engulf part of their contents. A comparison is made with a culture ofChlorarachnion reptans Geitler, according to earlier and own observations. Chloroplast structure as well as zoospore morphology confirm close affinities betweenCryptochlora andChlorarachnion. Generic characters as well as possible phylogenetic affinities with amoeboidXanthophyta andProtozoa are discussed.     

N G,N G -Dimethyl-l-arginine,a dominant precursor of endogenous dimethylamine in rats

Summary The metabolic significance ofN ^G ,N ^G -dimethyl-l-arginine (DMA) as a precursor of endogenous dimethylamine (DMN) in rats was examined in connection with the wide distribution and active operation of dimethylargininase (EC3.5.3.18) in rat tissues (Kimoto et al., 1993). When [methyl-¹⁴C]DMA was administered intraperitoneally to rats, the radioactive DMN was detected in various tissues as a major radioactive metabolite one hour after injection, and about 65% of the radioactivity administered was recovered in the first 12-h urine as DMN. In the case of the [¹⁴C] DMN-injected rats, almost all the radioactivity was excreted in the 12-h urine as DMN, except for a negligible amount of radioactivity found in urea. The time-dependent decrease in the specific radioactivity of DMA and DMN in urine showed that dimethylargininase was significantly involved in thein vivo formation of DMN by the hydrolytic cleavage of DMA released from methylated proteins and that DMA is a dominant precursor of endogenous DMN in rats.     

Maxillary sinusitis from Microascus cinereus and Aspergillus repens

Microascus was associated with Aspergillus repens in a left maxillary sinus. Tissue contained septale filaments of two types, conidia, ostiolate perithecia containing ascospores corresponding to Microascus cinereus which was identified by culture. The abundance of sexual fructifications in the tissue indicates that pathogenicity is due to Microascus cinereus.     

Entrapment and lysis of the cyanobacterium Phormidium luridum by aqueous colonies of Myxococcus xanthus PCO2

A Myxococcus xanthus isolate from a farm drainage ditch, designated strain PCO2, is capable of rapidly inducing lysis of both agar and liquid-grown cultures of the cyanobacterium, Phormidium luridum, var. olivacea. Microscopic studies of the predator-prey interaction demonstrate that lysis of the cyanobacterium occurs within clumps and spherules formed by the cells of M. xanthus PCO2. In the earliest stage, one sees the formation of irregular microclumps of bacteria and cyanobacterial filaments. As these clumps mature, colonies 1 to 6 mm in diameter develops. The center of these densely green colonies contains cyanohacteria in various stages of degradation, while the periphery is almost exclusively a tightly woven mass of myxobacterial cells. Electron microscopy shows that long extrusions from the outer membrane of the M. xanthus PCO2 cells are involved in the formation both of initial clumps and of mature colonial spherules. These extrusions appear to efficiently entangle the cyanobacterial filaments in the culture environment. Predator-to-prey ratios of 1/10, 1/100 and 1/1,000 have resulted in cyanobacterial lysis. Because the entrapment and lysis of P. luridum filaments by M. xanthus PCO2 appears to be independent of any other heterotrophic nutritional requirement, as well as of environmental agitation, this system has potential as a biological control technique for undesirable aquatic cyanobacteria.Abbreviations TEM transmission electron microscopy - SEM scanning electron microscopy - AB algae broth - ABT algae broth plus 0.2% tryptone     

唐松草属五新种

该文描述了毛茛科唐松草属五新种:(1)小花唐松草,发现自贵州东北部,与多枝唐松草近缘,区别为其小叶较小,雄蕊较少,花丝较短,呈狭条形。(2)新宁唐松草,发现自湖南南部,与爪哇唐松草近缘,区别为本种的雄蕊花丝呈狭条状棒形,花只含3~6枚心皮。(3)短蕊唐松草,发现自河南东南部,在体态上与爪哇唐松草十分相似,区别为本种的雄蕊很短,花丝呈丝形,花只含4~6枚心皮。(4)毛蕊唐松草,发现自四川北部,与长柄唐松草有密切的亲缘关系,区别为本种的茎和花梗被短柔毛,萼片被缘毛,花药不具短尖头,子房密被短柔毛。(5)小金唐松草,发现自四川西部,与白茎唐松草在亲缘关系上甚为相近,区别为本种的小叶被微硬毛,雄蕊花丝呈狭条形,花药顶端无短尖头或具极小短尖头,心皮较小,长仅2.4 mm,柱头无翅。     

Fungal infection for cyanobacterium <Emphasis Type="Italic">Anabaena smithii</Emphasis> by two chytrids in eutrophic region of large reservoir Lake Shumarinai,Hokkaido, Japan

Fungal infection of the filamentous cyanobacterium Anabaena smithii was observed in Lake Shumarinai in 2004–2006. Two fungal species were found to parasitize the specialized cells of A. smithii. These fungi might not correspond to the chytrid species that the previous studies reported as the parasites for Anabaena species. One fungus showed selective attachment to the akinete (akinete type). The filaments parasitized by this fungus increased in August 2004 and October 2006, when akinete and filament densities also increased. The maximum percentage of parasitized filaments was 3.2% of all filaments in October 2006. The other fungus was usually attached to the heterocyst (heterocyst type). The filaments parasitized by this fungus increased in October from 2004 to 2006. The maximum percentage of parasitized filaments was 20.6% in October 2004. The biomass of A. smithii was not suppressed by akinete-type fungus because of the low percentage of parasitized filaments. The heterocyst-type fungus might disturb the nitrogen fixation, but its effect was negligible due to a high concentration of available nitrogen for planktonic algae in Lake Shumarinai.