Getting a Grip on Complexes

We are witnessing tremendous advances in our understanding of the organization of life. Complete genomes are being deciphered with ever increasing speed and accuracy, thereby setting the stage for addressing the entire gene product repertoire of cells, towards understanding whole biological systems. Advances in bioinformatics and mass spectrometric techniques have revealed the multitude of interactions present in the proteome. Multiprotein complexes are emerging as a paramount cornerstone of biological activity, as many proteins appear to participate, stably or transiently, in large multisubunit assemblies. Analysis of the architecture of these assemblies and their manifold interactions is imperative for understanding their function at the molecular level. Structural genomics efforts have fostered the development of many technologies towards achieving the throughput required for studying system-wide single proteins and small interaction motifs at high resolution. The present shift in focus towards large multiprotein complexes, in particular in eukaryotes, now calls for a likewise concerted effort to develop and provide new technologies that are urgently required to produce in quality and quantity the plethora of multiprotein assemblies that form the complexome, and to routinely study their structure and function at the molecular level. Current efforts towards this objective are summarized and reviewed in this contribution.Key Words: Proteome, interactome, multiprotein assemblies, structural genomics, robotics, multigene expression, multiBac, BEVS, ACEMBL, complexomics.     

The chiasma-inducing pheromone of locusts

To the two quantitative criteria for phase transformation of locusts, viz. nymphal colour and adult morphometric ratios, the change in chiasma frequencies during meiosis in the male can now be added: gregarization or swarming induces an increase in chiasma formation. The atmosphere around crowded locusts contains a pheromone which is absorbed and causes a reactive haemolymph in locust hoppers. This haemolymph may be injected into solitarious hoppers or nymphs to induce increased chiasma formation. Certain solvents like risella oil and dimethyl sulphoxide will extract the pheromone from such an atmosphere, and bio-assays with these extracts have been demonstrated to be chiasma-inducing. Such extracts are, however, not chiasma-inducing in the albino mutant, but the haemolymph from crowded normal-coloured hoppers is reactive in the albino hopper. In addition the albino mutant is solitaria-like in both morphometric ratios and chiasma frequencies. These data indicate a relationship between the melanization cycle and chiasma induction: the previously postulated melanin-inducing pheromone and this chiasma-inducing pheromone are probably identical. On the other hand, this pheromone of nymphs and the sex-maturation pheromone of adults are not identical, although the latter may be a modified form of the other. The effect of the nymphal pheromone on adult morphometric ratios is not clear although some correlation has been shown to exist between raised chiasma frequencies in treated solitaries and advances towards gregaria ratios. It may be that in this pheromone we have, what may be called, a gregarizing principle.     

Oxygen consumption of flying locusts

ABSTRACT. Desert locusts ( Schistocerca gregaria Forskal.) were flown into an airstream from a wind tunnel while tethered to a balance. Rate of oxygen consumption and lift were recorded. The mean rate of oxygen consumption of male locusts in level flight at airspeeds between 2.5 and 3m/s was found to be 12.6ml/g/h.     

The cytogenetic systems of grasshoppers and locusts

Two new cases of supernumerary heterochromatic segments are described. One of these, found in a heterozygous state in eight males of Chorthippus jucundus, is present terminally on the short arm of the longest autosome. The other, present in a single male heterozygote of Trimerotropis tolteca modesta, is again terminally sited, this time on the long arm of the second smallest auto-some. Both segments are considered to be products of tandem duplication rather than translocation. The segment system of C. jucundus, like that of a number of other categories of heterochromatic material, produces a striking increase in mean cell chiasma frequency compared to basic homozygotes from the same population. It is argued that this effect of the segment on recombination provides a potential basis for selection leading to altered fitness. This, in turn, may well have determined the evolution of at least some forms of supernumerary material in natural populations.     

The cytogenetic systems of grasshoppers and locusts

The three endemic species of the Australian genusTolgadia are all distributed in the northern tropical and subtropical areas. They are distinguishable both on morphological and cytological grounds. All three have a derived neo XY, neo XX sex chromosome system involving distinct elements of a basically 11-membered autosome set, namely (spacies-1) (bivittata) and (infirma). Additionallybivittata is homozygous for two autosomal fusions involving and giving 2n=18 as compared to the complement of 2n=22 present in the other two species. Two of the species,bivittata and species-1, have a comparable mean cell chiasma frequency despite their difference in chromosome number. That ofinfirma is significantly higher. Coupled with this, some of the populations ofinfirma are polymorphic for supernumerary heterochromatic segments, principally on the smallest autosome. Such segments increase the mean cell chiasma frequency still further. Thusinfirma, which is the least habitat restricted despite its brachypterous nature, not only has the highest mean cell chiasma frequency but, in addition, has at its disposal a polymorphism capable of magnifying this difference.     

The gregarisation pheromone of locusts

Swarming locusts show three physical criteria, i.e. the phase changes of melanisation of the nymphal stages or hoppers, of the proportions of certain body parts (morphometric ratios), and increased genetic recombination (meiotic chiasma frequencies) in the adult. The control of these changes, initiated by aggregation into swarms, i.e. gregarisation, seems to be vested in a pheromone which is produced by all hoppers in both the solitaria and gregaria phases, also by hoppers of the albino strain. Such a pheromone can be extracted from the locust room air and from the locust, these extracts showing high activity in bioassays, primarily in increased chiasma frequencies but also in hopper colour. The extract in risella oil is more efficient than that in petroleum ether and can be distilled to yield an active distillate. The pheromone is secreted in the faeces of hoppers but not of adults. There is evidence in faeces bioassays that all three physical criteria are affected; the pheromone may be called locustone. It is manufactured or secreted in a specific section of the alimentary canal, i.e. the crop. Reception is not through the antennae but through the stigmata. Preliminary chemical analysis of a risella oil air extract distilled into various other solvents showed the presence of a relatively simple saturated aliphatic chain with a carbonyl function, perhaps a ketone or an ester.     

蝗虫化学信息物质研究进展

详述了蝗虫主要化学信息物质的种类、功能及主要成分等研究进展。蝗虫化学信息物质包括种内通讯的化学信息素和种间通讯的化学信息物质。其中种内通讯的化学信息素主要有群居信息素、成熟信息素、产卵信息素(含促产卵化学信息素和群集产卵化学信息素)、性信息素、聚集信息素等;种间通讯的化学信息物质主要介绍用于防卫的化学信息物质,包括卵分泌的信息物质、特定腺体分泌的信息物质、粪便挥发的信息物质、口腔分泌物和内部毒素等,对其天敌均有一定的防卫作用。化学通讯是蝗虫种内和种间通讯联系的普遍方式。     

Phase transformation and chiasma formation in locusts

The chiasmata in the eight longest of the eleven autosomes in spermatocytes of three species of locusts are greatly increased from the low basic number characteristic of the grasshopper-like or solitaria phase to higher numbers in the swarming or gregaria phase. Swarming in the field gives a greater impetus to the increase in chiasma frequency than crowding in cages. Although there seems to be some maternal effect acting on chiasma formation, the main correlation between population density and chiasma frequency seems to be effected during the last, or last two, instars of nymphal life. The effective factor is postulated to be present in the atmosphere, i.e. the air circulating in the locust breeding room and that circulating around a swarm in the field.In the species Locusía migratoria migratorioides three genetic factors have been found to control chiasma frequency. The first is a dominant factor reducing the frequency in one strain, the second is a possible polygenic complex reducing chiasma frequency in another strain selected for plasticity in hopper colour change, and the third is the recessive albino mutation which maintains chiasma frequency at the same level in crowded and solitary individuals.     

Auditory-evoked evasive manoeuvres in free-flying locusts and moths

We presented free-flying locusts (Locusta migratoria L.) with sounds that varied in temporal structure and carrier frequency as they flew toward a light source in a flight room under controlled temperature and light conditions. Previous studies have shown tethered locusts react more often to trains of 30-kHz pulses than to pulse trains below 10 kHz. Further, this acoustic startle response has been suggested to function in bat-avoidance. We expected free-flying locusts to respond similarly; however, we found locusts responded to all sounds we presented, not just high-frequency, bat-like sounds. Response rates of turns, loops, and dives varied from 6% to 26% but were statistically independent of carrier frequency and/or pulse structure. Free-flying moths and tethered locusts were tested using a subset of our acoustic stimuli under the same temperature and light conditions as the free-flying locusts. Moth responses were carrier frequency dependent as were responses of tethered locusts positioned along the flight path observed in our free-flight trials. All responses were unaffected by a 90% reduction in room light. We conclude that locusts possess an acoustic startle response evocable in free flight, however, free-flying locusts do not show the same discrimination observed in tethered locusts under similar conditions.Abbreviations ASR acoustic startle response - dB SPL decibel sound pressure level (RMS re: 20 Pa)     

Diurnal rhythms of supercooling in locusts

When locusts are exposed to diurnal cycles of LD 6:18, which are known to elicit a clear circadian periodicity in these insects, the supercooling point is lower in the dark than in the light phase — significantly so in the case ofL. migratoria. The adaptive value of this is that it enables the animals to withstand colder conditions. It is argued that the rhythm is probably endogenous and coupled with the circadian locomotory rhythm.     

菏泽市蝗虫调查初报

近年对山东省菏泽市的蝗虫资源进行了调查,结果显示蝗亚目昆虫23种,分隶于2总科7科20属,分布于黄河滩地、库洼地、缓平坡地、低山残丘四种生态环境。明确了各种生态环境的优势种、常见种和稀少种,其区系为古北与东洋界过渡地带,古北种、东洋种均占相当比例,广布种具明显优势。     

新疆蝗虫及其监控技术研究进展

因蝗虫种群种类多、分布范围广,导致新疆是我国蝗虫灾害发生最突出、最典型的地区,也是遭受邻国蝗虫跨境危害最严重的地区。本文概述了几十年来新疆蝗虫基础理论研究及监测预警与防控技术进展,同时总结了中哈边境蝗虫跨境迁飞过程及雷达监测的最新研究结果,并就中亚迁飞场理论和实证研究、区域迁飞害虫监测网络平台建立和生物防治技术三个方面进行了展望,以期为监测和治理新疆本地蝗虫及西北边境迁飞害虫提供科学依据和技术支撑。