Mitochondrial location of pyruvate carboxylase in Aspergillus niger

Pyruvate carboxylase has been found in the mitochondrial fraction of two strains of Aspergillus niger along with the marker enzymes of citrate synthase and cytochrome c oxidase. The location of pyruvate carboxylase in A. nidulans was, however, confirmed to be in the cytosolic fraction. The enzyme from the former sources was dependent upon the presence of acetyl-CoA for full activity; the enzyme from A. nidulans was unaffected by the presence or absence of acetyl-CoA.     

Flight behaviour of Encarsia formosa in response to plant and host stimuli

The flight behaviour of Encarsia formosa Gahan (Hymenoptera: Aphelinidae), a parasitoid of Trialeurodes vaporariorum (Westwood) (Homoptera: Aleyrodidae) has been studied in response to the following natural components: bean plant (Phaseolus vulgaris L.) infested with T. vaporariorum (PHC, plant host complex), host damaged bean plant from which whiteflies were removed (HDP, host damaged plant), T. vaporariorum third instar larvae (H, host), uninfested bean plant (P, plant) and T. vaporariorum empty pupal cases (EPC, empty pupal cases). A combination of chemical and visual stimuli is necessary in host location from a distance by E. formosa and seems to deeply affect the dispersal of this parasitoid. The presence of host (PHC, H) or of its parts (EPC) led to a substantial increase of oriented flights suggesting the occurrence of host derived chemicals. At a closer range, a combination of visual and chemical stimuli deriving from all the components of the plant host complex elicited the transition flying-landing and the following landing on the source.     

Survivorship of geographic Pomacea canaliculata populations in responses to cold acclimation

1. Pomacea canaliculata, a freshwater snail from South America, has rapidly established natural populations from south to north subtropical region in China, since its original introductions in the 1980s. Low temperature in winter is a limiting factor in the geographic expansion and successfully establishment for apple snail populations. There have been some studies on population level of low temperature tolerance for P. canaliculata, yet little is quantified about its life‐history traits in responses to cold temperatures. Whether these responses vary with the acclimation location is also unclear. We investigated the survivorship and longevity of P. canaliculata in responses to cold temperatures and examine whether these responses vary with the location and snail size. We hypothesized that survival of the snails depends on their shell height and the level of low temperature, and P. canaliculata population from the mid-subtropical zone may exhibit the highest viability over the cold thermal range.
2. We sampled P. canaliculata populations from five latitude and longitude ranges of subtropical China: Guangzhou population in southernmost (SM‐GZ), three populations of Yingtan (MR‐YT), Ningbo (MR‐NB), Ya'an (MR‐YA) in midrange, and Huanggang population in northernmost (NM‐HG) subtropical zone. For each P. canaliculata population, survival and longevity at six cold acclimation temperature levels (12, 9, 6, 3, 0, and ?3°C) were quantified, and the effects of location and shell height were examined.
3. The MR‐YA population from mid-subtropical zone of China exhibited the highest survival rate and prolonged survival time regardless of the temperature acclimation treatments, whereas the SM‐GZ population from southern subtropical was the most sensitive to cold temperatures, particular temperatures below 9°C. No individuals of the SM‐GZ population could survive after stressed for 30 days (3°C), 5 days (0°C) and 2 days (?3°C), respectively. For each experimental P. canaliculata population held at 3, 0, and ?3°C, individuals with intermediate shell height of 15.0–25.0 mm had significantly higher survivals.
4. The results highlight a request of a more thorough investigation on acclimation responses in each of the life table demographic parameters for P. canaliculata, and pose the question of whether natural selection or some genetic changes may have facilitated adaptation in invasive locations.

     

Response of the egg parasitoid Trichogramma pretiosum to the sex pheromone of its host Heliothis zea

This paper presents results of olfactometer experiments with the egg parasitoid Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae) and its host the corn earworm moth, Heliothis zea (Boddie) (Lepidoptera: Noctuidae). The sex pheromone of the host significantly reduced the total number of border crossings between odour fields in the olfactometer. Also, female parasitoids made significantly more visits to the calling moth odour field than to the opposite control field in the olfactometer. Further, the wasps spent significantly more time in the olfactometer field containing the sex pheromone released by calling virgin moths, than in control fields. If non-calling virgin moths were used as odour source, the response was reversed and wasps were repelled by the odour of the moths, and the numbers of visits were evenly distributed over the four flow fields. These results are discussed in the context of foraging ecology of egg parasitoids.

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Résumé Des expériences menées en olfactométrie avec le parasite oophage Trichogramma pretiosum Riley (Hymenoptera: Trichogrammatidae) et son hôte, Heliothis zea (Boddie) (Lepidoptera: Noctuidae) donnent les résultats suivants. La présence de la phéromone sexuelle de l'hôte réduit de façon significative le nombre de passages entre les champs odorisés. De mème, les parasites visitent plus fréquemment le champ qui dispense l'odeur de la femelle en appel que le champ témoin placé à l'opposé. Par ailleurs, le temps passé dans le champ qui contient la phéromone sexuelle émise par les femelles vierges en appel est significativement supérieur à la durée de visite des champs témoins. Si l'on utilise comme source d'odeur des femelles vierges qui ne sont pas en appel, la réponse est inversée, les parasites sont alors repoussés par l'odeur de ces papillons et le nombre de visites est distribué de façon aléatoire entre les quatre champs. Ces résultats sont discutés dans le contexte de l'écologie du comportement de recherche chez les parasites oophages.

     

Deep-lipidotyping by mass spectrometry: recent technical advances and applications

In-depth structural characterization of lipids is an essential component of lipidomics. There has been a rapid expansion of mass spectrometry methods that are capable of resolving lipid isomers at various structural levels over the past decade. These developments finally make deep-lipidotyping possible, which provides new means to study lipid metabolism and discover new lipid biomarkers. In this review, we discuss recent advancements in tandem mass spectrometry (MS/MS) methods for identification of complex lipids beyond the species (known headgroup information) and molecular species (known chain composition) levels. These include identification at the levels of carbon-carbon double bond (C=C) location and sn-position, as well as characterization of acyl chain modifications. We also discuss the integration of isomer-resolving MS/MS methods with different lipid analysis workflows and their applications in lipidomics. The results showcase the distinct capabilities of deep-lipidotyping in untangling the metabolism of individual isomers and sensitive phenotyping by using relative fractional quantitation of the isomers.     

Isovaleronitrile co-induced with its precursor,l-leucine,by herbivory in the common evening primrose stimulates foraging behavior of the predatory blue shield bug

Herbivore-induced plant volatiles play important roles in plant–insect and plant–plant interactions. The common evening primrose, Oenothera biennis, is often infested by the flea beetle, Altica oleracea, on which the predatory blue shield bug, Zicrona caerulea, is usually found. This observation suggests that the predatory bug can discriminate infested plants from intact ones to locate its prey. In this study, l-leucine-derived nitrogen-containing compounds [isovaleronitrile (3-methylbutanenitrile), (E/Z)-isovaleraldoxime and 3-methyl-1-nitrobutane] and some terpenes were identified as a characteristic volatile blend from herbivore-infested O. biennis leaves by gas chromatography/mass spectrometry, chemical synthesis, and incorporation assays using deuterium-labeled l-leucine. Volatile emission was also elicited by exogenous methyl jasmonate (MeJA), but not by mechanical damage. l-Leucine accumulated temporarily in O. biennis leaves after MeJA treatment prior to isovaleronitrile emission. Behavioral assays revealed that Z. caerulea showed a strong preference for herbivore-infested leaves, their volatiles, and isovaleronitrile in laboratory conditions.     

Chloroplast position and photosynthetic characteristics in two monostromatic species,Monostroma angicava and Protomonostroma undulatum (Ulvophyceae), having a shared ecological niche

Monostroma angicava and Protomonostroma undulatum are monostromatic green benthic algae (Ulvophyceae), which grow together in the same intertidal habitat of Muroran, Hokkaido, Japan, during the spring season. Commonly, both species have a single chloroplast with one pyrenoid per cell. The parietal chloroplast is located on the periphery of the thallus in both species, although the location of the chloroplast differs in the two. In M. angicava , the chloroplast was observed to be arranged on one‐side of the thallus surface, whereas, in P. undulatum , it was dispersed and randomly located on either side of the thallus or on the lateral face. The density of chlorophylls (Chls) assessed from the absorption spectra of the thallus and its solvent extract was higher in M. angicava , which appeared dark‐green in color, than in the light‐green colored P. undulatum . The maximum photosynthetic rate per thallus area (μmol O₂ m^?2 s^?1) was higher in M. angicava , whereas, per total chlorophyll content (μmol O₂ g Chl a + Chl b ^?1 s^?1) was higher in P. undulatum . Both species showed similar efficiency of photosynthesis at light‐limiting conditions. The efficiency of light absorption by photosystem II (PSII ) in P. undulatum was higher than M. angicava , whereas the photoprotective response was higher in M. angicava . This indicates that more energy is utilized in M. angicava to protect its PSII due to the chloroplast position, which has more direct exposure to light and, therefore, lowers the efficiency of light absorption by PSII . The higher density of chlorophylls in M. angicava could explain higher photosynthesis per thallus area, whereas, higher efficiency of light absorption by PSII in P. undulatum could explain higher photosynthesis per total chlorophyll content. The differences in light absorption efficiency and quantum efficiency of PSII might be an important ecological strategy in these two species for their coexistence in the intertidal area.     

近年来中国热带地区外来有害昆虫的种类特征及入侵分析

我国热带地区是外来入侵物种发生与危害的重灾区,近年来外来有害昆虫入侵所引发的生物灾害及生态安全问题日趋严峻。在海南省、广东省、广西壮族自治区、云南省、福建省外来入侵昆虫的调查结果及文献资料的基础上,整理分析了中国热带地区外来入侵昆虫的种类构成、分布、原产地及首次发现地。据统计,2000-2014年我国热带地区的外来入侵昆虫种类共计23种,隶属于6目11科,数量最多的为半翅目(13种,56.52%),其中以粉蚧科和粉虱科居多;热带地区的外来入侵昆虫在不同地区之间的物种数量差异较大,其中海南省最多(19种,82.61%),其后依次为广东省(16种,69.57%)、云南省(14种,60.87%)、广西壮族自治区(12种,52.17%),而福建省最少(9种,占39.13%);在入侵我国热带地区的外来有害昆虫中,原产于亚洲、北美洲的种类最多均为6种,占26.09%,南美洲占21.74%,而从非洲、大洋洲、欧洲传入的分别占8.70%、4.35%、4.35%;外来入侵昆虫的首次发现地位于广东省的有9种,占39.13%,出现在海南省和云南省的各占30.43%、21.74%,出现在广西壮族自治区的为8.70%。阐明我国热带地区外来有害昆虫的种类特征及入侵现状,可为该地区外来入侵昆虫的监测与防控提供一定的依据。     

Replication Timing of Amplified Genetic Regions Relates to Intranuclear Localization but Not to Genetic Activity or G/R Band

Amplified genes in many human cancer cells usually localize at the extrachromosomal double minutes (DMs). In the present study, we show that multiple DMs in the human colorectal tumor COLO 320DM line replicated semisynchronously during the early S phase. On the other hand, during longer passage of the cells with DMs, cells with the amplified genes at the chromosomal homogeneously staining region (HSR) generally dominate the population. We currently report that HSR was composed of a tandem array of DM-derived sequences, which was shown using a unique DM-painting probe. Nevertheless, we found that HSR was replicated much later during the S phase, unless the amplified c-myc genes were expressed almost equally from DMs and HSR. Therefore, this provided a novel instance in which the cytogenetic localization affected replication timing without alteration of expression. Furthermore, we unexpectedly found that HSR had a distinctive band structure with respect to replication timing. The replication band structure was usually associated with the chromosomal G/R bands; however, HSR was homogeneous in the G/R band and in the distribution of highly repetitive sequences. We discuss the mechanism by which the replication band may arise, in relation to the folding of chromatin inside the nucleus.