Anatomy of the ocellar interneurons of acridid grasshoppers

Summary The anatomy of the small ocellar interneurons in the brain of the acridid grasshopper Schistocerca vaga was revealed by cobalt-filling the three ocellar nerves and subsequent reconstructions from silver-intensified (Timm's method) serial sections.In total, 61 small ocellar interneurons were repeatedly identified with arborizations in many areas of the brain and optic lobe, including in particular the posterior neuropil, ocellar tracts, protocerebral bridge, lobula, ventral bridge and tritocerebral crotch, calyces, and antenno-glomerular tracts.Each ocellar nerve contains the axons of small cells that arborize in the other two ocellar tracts; these tracts are sites of ocellar integration. Direct interactions between the ocelli and compound eyes are suggested by the projections of small ocellar interneurons into the proximal lobula. Small cell arborizations from all three ocelli are distributed across much of the protocerebral bridge, implying a role for the bridge as an ocellar neuropil within the brain.Four of the small interneurons could be seen in whole-mount preparations and are demonstrated to be identical in five species of acridid grasshoppers of two different subfamilies: Schistocerca vaga, S. gregaria, Gastrimargus africanus, Trimerotropis pallidipennis, and Arphia conspersa.     

Equilocality of heterochromatin distribution and heterochromatin heterogeneity in acridid grasshoppers

Comparative fluorescence studies on the chromosome of ten species of acridid grasshoppers, with varying amounts and locations of C-band positive heterochromatin, indicate that the only regions to fluoresce differentially are those that C-band. Within a given species there is a marked tendency for groups of chromosomes to accumulate heterochromatin with similar fluorescence behaviour at similar sites. This applies to all three major categories of heterochromatin — centric, interstitial and telomeric. Different sites within the same complement, however, tend to have different fluorescence properties. In particular, centric C-bands within a given species are regularly distinguishable in their behaviour from telomeric C-bands. Different species, on the other hand, may show distinct forms of differential fluorescence at equilocal sites. These varying patterns of heterochromatin heterogeneity, both within and between species, indicate that whatever determines the differential response to fluorochromes has tended to operate both on an equilocal basis and in a concerted fashion. This is reinforced by the fact that structural rearrangements that lead to the relocation of centric C-bands, either within or between species, may also be accompanied by a change in fluorescence behaviour.We dedicate this paper, with affection, to Professor Hans Bauer on the occasion of his 80th birthday, and in appreciation of his singular contribution to the study of chromosomes     

Stridulation of acridid grasshoppers after hemisection of thoracic ganglia: evidence for hemiganglionic oscillators

In the grasshopperChorthippus biguttulus the stridulatory movements of males with surgically manipulated ventral nerve cords were investigated.

Phenoloxidase activity in organisms isolated from lepromatous and tuberculoid leprosy

Anaerobic corynebacteria (propionibacteria), isolated in pure culture from the plasma of a case of tuberculoid leprosy and from lepromata of cases of lepromatous leprosy, exhibited phenoloxidase activity such as that shown by Prabhakaran to be associated with leprosy bacilli harvested from patients suffering from leprosy. Several corynebacteria, mycobacteria, and nocardias similarly examined did not produce phenoloxidase.     

Stridulatory pattern generation in acridid grasshoppers: metathoracic interneurons in Stenobothrus rubicundus (Germar 1817)

Stridulation was elicited in tethered gomphocerine grasshoppers of the species Stenobothrus rubicundus in order to identify interneurons of the stridulation pattern generator, and describe their morphological and physiological properties. Nine types of such neurons could be found and characterized; eight of those could additionally be compared to corresponding neuron types previously known from other species. As shown in detail for one selected type, the neurons of the stridulation pattern generator are very similar in their anatomical appearance, and possess similar physiological qualities at least in two species with similar stridulation patterns. Stridulation interneurons of species with largely different stridulatory motor patterns have a similar morphology, but show a different activation timing throughout the stridulation. Nevertheless, special properties such as resetting or initiation capability of certain stridulation interneurons seem to be conserved throughout the species. The results suggest that the stridulation pattern generator of different species consists of a uniform set of interneurons that change their activity pattern to produce species-specific song movements.     

Phenoloxidase activity in the haemolymph of parasitized and unparasitized Heliothis virescens

Hymenopterous parasitoids of Heliothis virescens are able to evade the immune mechanisms of their host, especially the ability of the host to encapsulate foreign objects within a haemocyte capsule. This encapsulation is often accompanied by melanization. Our present findings show that hosts parasitized by Microplitis croceipes, Cardiochiles nigriceps and Campoletis sonorensis show changes both in the amount of melanin formed when their haemolymph is exposed to air and in the total protein as determined by the Folin phenol reagent. Furthermore, these changes are promoted by each of the three parasitoids in a different way. However, none of these parasitoids was able to alter the levels of host phenoloxidase as measured by the ability of the haemolymph to convert 4-methylcatechol to its quinone. The hymenopteran egg must therefore escape encapsulation in Heliothis in a way other than through inhibition of phenoloxidase, since the melanization reactions in the host's haemolymph are apparently unimpaired, particularly during the egg stage, by either the egg or venom of any one of the three parasitoids.     

Evolutionary dynamics of 5S rDNA location in acridid grasshoppers and its relationship with H3 histone gene and 45S rDNA location

We analyze the chromosomal location of 5S rDNA clusters in 29 species of grasshoppers belonging to the family Acrididae. There was extensive variation among species for the number and location of 5S rDNA sites. Out of 148 sites detected, 75% were proximally located, 21.6% were interstitial, and only 3.4% were distal. The number of 5S rDNA sites per species varied from a single chromosome pair (in six species) to all chromosome pairs (in five species), with a range of intermediate situations. Thirteen chromosomes from eight species carried two 5S rDNA clusters. At intraspecific level, differences among populations were detected in Eyprepocnemis plorans, and some heteromorphisms have also been observed in some species. Double FISH for 5S rDNA and H3 histone gene DNA, performed on 17 of these 29 species, revealed that both markers are sometimes placed in a same chromosome but at different location, whereas they appeared to co-localize in five species (Calliptamus barbarus, Heteracris adpersa, Aiolopus strepens, Oedipoda charpentieri and O. coerulescens). Double fiber-FISH in A. strepens and O. coerulescens showed that the two DNAs are closely interspersed with variable relative amounts of both classes of DNA. Finally, no correlation was observed between the number of 5S and 45S rDNA clusters in 23 species where this information was available. These results are discussed in the light of possible mechanisms of spread that led to the extensive variation in the number of clusters observed for both rDNA types in acridid grasshoppers.     

Phenoloxidase activity in the hemolymph of the spiny lobster Panulirus argus

The prophenoloxidase activating system plays a major role in the defense mechanism of arthropods. In the present study, the phenoloxidase activity and its location in the hemolymph of the spiny lobster Panulirus argus is presented. Phenoloxidase activity was observed in the hemocyte lysate supernatant (HLS) and plasma after their incubation with trypsin. Higher amounts of trypsin were required to activate the HLS prophenoloxidase, due to the presence of a trypsin inhibitor in this fraction. Activation of prophenoloxidase was found when HLS was incubated with calcium, with an optimal pH between 7.5 and 8. This spontaneous activity is due to the prophenoloxidase activating enzyme, a serine proteinase that activates the prophenoloxidase once calcium ions were available. SDS was able to induce phenoloxidase activity in plasma and hemocyte fractions. Prophenoloxidase from HLS occurs as an aggregate of 300kDa. Electrophoretic studies combining SDS-PAGE and native PAGE indicate that different proteins produced the phenoloxidase activity found in HLS and plasma. Thus, as in most crustaceans, Panulirus argus contains a prophenoloxidase activating system in its hemocyte, comprising at least the prophenoloxidase activating enzyme and the prophenoloxidase. Finally, it is suggested that phenoloxidase activity found in plasma is produced by hemocyanin.     

Monograph of the Afrotropical species of Scelio Latreille (Hymenoptera,Platygastridae), egg parasitoids of acridid grasshoppers (Orthoptera,Acrididae)

The genus Scelio is a cosmopolitan and speciose group of solitary parasitoids of the eggs of short-horned grasshoppers (Orthoptera: Acrididae). A number of these hosts are important pests, including plague locusts of the genus Schistocerca. Species of Scelio are recognized as potentially important biological control agents, but this possibility has yet to be fully realized, in part because the species-level taxonomy is still incompletely developed. The species of the pulchripennis group have been recently revised. As a continuation of this effort, here we revise the Afrotropical species of Scelio, excluding the pulchripennis species group. Sixty two (62) species are treated, 48 of which are new. Species are classified into the following species groups: ernstii (12 species, 9 new), howardi (23 species, 19 new), ipomeae (6 species, 5 new), irwini (4 species, 3 new), simoni (3 new species) and walkeri (12 species, 9 new). Keys to species groups and to the species within each group are provided. New species described are: S. albatus Yoder, sp. n., S. aphares Yoder, sp. n., S. apospastos Yoder, sp. n., S. ardelio Yoder, sp. n., S. aurantium Yoder, sp. n., S. balo Valerio & Yoder, sp. n., S. bayanga Yoder, sp. n., S. bubulo Yoder, sp. n., S. cano Yoder, sp. n., S. clypeatus Yoder, sp. n., S. concavus Yoder, sp. n., S. copelandi Yoder, sp. n., S. crepo Yoder, sp. n., S. destico Yoder, sp. n., S. dupondi Yoder, sp. n., S. effervesco Yoder, sp. n., S. erugatus Yoder, sp. n., S. exophthalmus Yoder, sp. n., S. fremo Valerio & Yoder, sp. n., S. gemo Yoder, sp. n., S. grunnio Yoder, sp. n., S. harinhalai Yoder, sp. n., S. igland Yoder, sp. n., S. impostor Yoder, sp. n., S. irwini Yoder, sp. n., S. janseni Yoder, sp. n., S. latro Yoder, sp. n., S. memorabilis Yoder, sp. n., S. modulus Yoder, sp. n., S. mutio Yoder, sp. n., S. ntchisii Yoder, sp. n., S. parkeri Yoder, sp. n., S. phaeoprora Yoder, sp. n., S. pilosilatus Yoder, sp. n., S. pipilo Yoder, sp. n., S. quasiclypeatus Yoder, sp. n., S. retifrons Yoder, sp. n., S. ructo Yoder, sp. n., S. scomma Yoder, sp. n., S. simoni Yoder, sp. n., S. simonolus Yoder, sp. n., S. somaliensis Yoder, sp. n., S. susurro Yoder, sp. n., S. tono Yoder, sp. n., S. transtrum Yoder, sp. n., S. tritus Yoder, sp. n., S. ululo Yoder, sp. n., S. vannoorti Valerio & Yoder, sp. n. The following species are redescribed: S. afer Kieffer, S. chapmani Nixon, S. howardi Crawford, S. ipomeae Risbec, stat. n., S. mauritanicus Risbec, S. philippinensis Ashmead, S. remaudierei Ferrière, S. striatus Priesner,S. taylori Nixon, and S. zolotarevskyi Ferrière. The genus Lepidoscelio Kieffer is treated as a junior synonym of Scelio Latreille, syn. n.; its type species, Lepidoscelio fuscipennis Kieffer, 1905 is transferred to Scelio, renamed Scelio obscuripennis Johnson, nom. n. (preoccupied by Scelio fuscipennis Ashmead, 1887), and redescribed. The following additional species are transferred from Lepidoscelio to Scelio: S. cayennensis (Risbec), comb. n., S. insularis Ashmead, rev. comb., S. luteus (Cameron), comb. n., S. thoracicus Ashmead, rev. comb. Lectotypes are designated for S. africanus Risbec, S. ipomeae Risbec, S. mauritanicus Risbec, S. remaudierei Ferrière, S. sudanensis Ferrière, and S. zolotarevskyi Ferrière. Scelio gaudens Nixon is a junior synonym of Scelio striatus Priesner, syn. n.; Scelio africanus Risbec and Scelio clarus Fouts are both junior synonyms of Scelio afer Kieffer, syn. n.; Scelio sudanensis Ferrière and Scelio cheops Nixon are both junior synonyms of Scelio zolotarevskyi Ferrière, syn. n.; Scelio cahirensis Priesner is a junior synonym of Scelio mauritanicus Risbec, syn. n. The name Scelio chapmanni Nixon is an incorrect original spelling, requiring an emendation to S. chapmani. Digital versions of the identification keys are available at http://www.waspweb.org/Platygastroidea/Keys/index.htm     

Phenoloxidase activity and thermostability of Cancer pagurus and Limulus polyphemus hemocyanin

The intrinsic and inducible o-diphenoloxidase (o-diPO) activity of Cancer pagurus hemocyanin (CpH) and Limulus polyphemus hemocyanin (LpH) were studied using catechol, l-Dopa and dopamine as substrates. The kinetic analysis shows that dopamine is a more specific substrate for CpH than catechol and l-Dopa (K_m value of 0.01 mM for dopamine versus 0.67 mM for catechol, and 2.14 mM for l-Dopa), while k_cat is highest for catechol (2.44 min^? 1 versus 0.67 min^? 1 for l-Dopa and 0.71 min^? 1 for dopamine). On treatment with 4 mM sodium dodecyl sulfate (SDS) or by proteolysis the o-diPO activity of CpH increases about twofold. In contrast, native LpH shows no o-diPO activity, and exhibits only a slight activity after incubation with SDS. Neither CpH nor LpH show intrinsic mono-PO activity with l-tyrosine and tyramine as substrates. To explore the possible correlation between the degree of PO activity and protein stability of arthropod hemocyanins, the thermal stability of CpH and LpH was investigated by differential scanning calorimetry and Fourier transform infrared spectroscopy. CpH is found to be less thermostable (T_m ~ 80 °C), suggesting that the dicopper active sites are more accessible, thereby allowing the hemocyanin to show PO activity in the native state. The LpH, on the other hand, is more thermostable (T_m ~ 92 °C), suggesting the existence of a correlation between the thermal stability and the intrinsic PO activity of arthropod hemocyanins.     

Response of grasshoppers (Orthoptera: Acrididae) to livestock grazing in southeastern Arizona: differences between seasons and subfamilies

Summary Grasshopper densities were compared between grazed and ungrazed semidesert grassland sites in southeastern Arizona. Bouteloua-dominated perennial grass cover was about 1.5 times greater on the livestock exclosure. Grasshoppers were 3.7 times more abundant on the protected area in the summers of 1983 and 1984, when dominant species were grass-feeding members of the subfamily Gomphocerinae. In fall 1984, grasshoppers were 3.8 times more common on the grazed site, when dominants were mainly herb-feeders in the subfamily Melanoplinae. These results indicate important seasonal and taxonomic differences in the responses of grasshoppers to the activities of vertebrate grazers.     

绿僵菌侵染对椰心叶甲酚氧化酶活性的影响

对椰心叶甲Brontispa longissima(Gestro)成虫血淋巴中酚氧化酶的特性进行分析,并研究绿僵菌(Metarhizium anisopliae)侵染对血浆甲酚氧化酶活性的影响。结果显示,椰心叶甲成虫的血浆及血细胞裂解液中均检测到酚氧化酶活性,且昆布多糖及胰蛋白酶可显著提高其活性。绿僵菌MA-4侵染组在侵染后第1至第5d的血浆酚氧化酶活性高于未侵染组(P<0.05),但是椰心叶甲成虫体内注射10μg昆布多糖后,侵染组的酚氧化酶活性显著低于未侵染组(P<0.05),表明绿僵菌一方面对可激活椰心叶甲的酚氧化酶原激活系统,另一方面又可抑制昆布多糖对椰心叶甲酚氧化酶原激活系统的诱导作用。     

Phenoloxidase activity and pathogen resistance in yellow dung flies Scathophaga stercoraria

Phenoloxidase (PO) is an important component of the insect immune system and is frequently used to measure an individual's immune defence ability. However, evidence documenting positive correlations between the immune assay and resistance against pathogens is scarce and contradictory. We used replicate lines of yellow dung flies Scathophaga stercoraria (L.) with different PO levels to investigate whether PO levels affect resistance against parasitic mites and entomopathogenic fungi. Prevalence of flies exposed to pathogens was the same in all selection regimes, although pathogens clearly negatively affected fitness. PO measurements alone therefore do not necessarily predict overall resistance against pathogens. Furthermore, under starvation lines selected for high PO levels did not survive longer than those selected for low PO levels, irrespective of exposure to pathogens. This suggests that even if elevated immune levels increase an individual's ability to combat pathogens, the benefits may not outweigh the costs of increased investment in immunity.     

中国对虾（Penaeus chinensis）酚氧化酶的分离纯化及其部分生物化学性质

以中国对虾 (Penaeuschinensis)的血淋巴为材料 ,利用凝胶过滤和离子交换等方法 ,对酚氧化酶 (phe noloxidase ,E .C .1 .1 0 .3.1 )进行了分离纯化和生物化学性质研究。实验发现 ,酚氧化酶原 (prophenoloxidase)的分子量为 87.5kD左右 ,在实验操作过程中极易发生降解或自身降解 ,变成有活性的大小约 77kD的酚氧化酶 ,1 0g/LSDS可使该酶原全部被激活而成为有活性的酚氧化酶。以L 二羟苯丙氨酸 (L DOPA)为特异性底物对酚氧化酶活性进行研究发现 ,其最适pH值为 6 .0左右 ,最适温度为 4 0℃ ,Km 值约为 1 .99mmol/L。利用多种氧化酶抑制剂对酚氧化酶纯化样品的酶活性进行研究 ,发现抗坏血酸 (ascorbicacid)、半胱氨酸 (cysteine)和二硫苏糖醇(dithiothreitol)对酚氧化酶活性具有很强的抑制作用 ,硫脲 (thiourea)对酚氧化酶活性也具有较强的抑制作用 ,而酚氧化酶对苯甲酸 (benzoicacid)、柠檬酸 (citricacid)和亚硫酸钠 (sodiumsulfite)不敏感 ,而且该酶对酪氨酸等单酚还具有高特异性的酚氧化酶活性 ,表明它可能是一种酪氨酸酶型的酚氧化酶 ;此外 ,该酶对EDTA和金属离子非常敏感 ,其活性能被Cu2 强烈抑制 ,被Mg2 强烈激活 ,表明该酶很可能是一种金属酶 (metalloenzyme)     

Phenoloxidase activity of intact and chemically modified functional unit RvH1: a from molluscan Rapana venosa hemocyanin

o-Diphenol oxidase activities (o-diPO) of chemically modified functional unit RvH1-a of molluscan hemocyanin Rapana venosa were studied using L-Dopa and dopamine as substrates. With L-Dopa as substrate the native FU RvH1-a did not show any o-diPO activity. Therefore the native FU RvH1-a was converted to enzymatic active form, after treatment with SDS, trypsin, urea and different values of pH when its o-diPO activity was studied. The highest artificial induction of o-diPO activity was observed after incubation of FU with 3.0mM SDS, and RvH1-a shows both, dopamine (K(M)=6.53mM, k(cat)/K(M)=1.29) and L-Dopa (K(M)=2.0mM, k(cat)/K(M)=2.1) activity due to a more open active site of the enzyme and better access of the substrates. It was determined that the K(M) value of SDS-activated RvH1-a against dopamine is higher compared to those of hemocyanins from Helix vulgaris, Helix pomatia and native tyrosinase from Ipomoea batatas but much lower than that from Illex argentinus (ST94) tyrosinase and arthropodan hemocyanin from Carcinus aestuarii. The Km value of SDS-activated RvH1-a against L-Dopa is higher than those of hemocyanins from H. vulgaris and Cancer magister, but lower than that of the tyrosinase from Streptomyces albus.     

Ostracoda of the subfamilies Protocytherinae and Trachyleberidinae from the British Lower Cretaceous

The distribution and range of the members of these two subfamilies are given for material of Hauterivian, Barremian, Aptian and Albian age from the Speeton Clay in Yorkshire, England. Eleven species are described and figured of whichProtocythere gaultina, Protocythere intermedia, Protocythere mertensi, Protocythere speetonensis, Homocythere reticulata, Cythereis blanda andCythereis lamplughi are new. The genusHomocythere is described for the first time. An ontogenetic study ofProtocythere triplicata (F. A. Roemer) is undertaken.     

The heterochromatin of grasshoppers from the Caledia captiva species complex

C-band variation between the Caledia taxa is extensive with numerous large interstitial and telomeric blocks of heterochromatin being present in the South-east Australian and Moreton taxa while the Torresian types possess small centromeric or telomeric C-bands. In situ hybridization using ³H-cRNA from a 168 bp (base pairs) highly repeated sequence, originally isolated from the South-east Australian taxon, defined further variation between the C. captiva taxa. This sequence family is present in each of the interstitial and telomeric constitutive heterochromatic blocks in the South-east Australian and Moreton taxa. However, it is represented in only a fraction of the heterochromatic regions, defined by C-banding, within the three Torresian types. A second, unrelated 144 bp sequence family, originally isolated from the Daintree taxon, is restricted to the procentric blocks of heterochromatin of chromosomes 2–7, 9 and 10 in the Daintree taxon. This sequence is A-T rich and possesses a region of dyad symmetry. Quantitative measurements for the two sequence families revealed a wide range of copy numbers between the C. captiva taxa. The 168 bp family has approximately 150,000, 35,000 and 4,000 copies, respectively, in the South-east Australian/ Moreton, Torresian and Daintree genomes. There are 2,000,000 and 100,000 copies of the 144 bp sequence in the Daintree and Papuan Torresian taxa, respectively. The distributional, quantitative and sequence characteristics of these repeat families imply that past amplification or introgression has played a major role in the evolution of these sequences. There is an overall negative correlation between the quantity of the 168 bp sequence and the levels of reproductive isolation and genie divergence between the various taxa. It is possible that some of the reduction in the viability of the hybrid individuals is due to the quantitative changes in these sequences. Moreover, the quantitative and qualitative characteristics of highly repeated DNA families may play a role in the modulation of such essential cellular functions as cell cycle duration, nuclear organization and gene expression.     

The heterochromatin of grasshoppers from the Caledia captiva species complex

A highly repeated family of sequences from the grasshopper Caledia captiva shows a dispersed distribution at the cytological level. Members of this 185 bp sequence family are not restricted to C-band heterochromatin, but rather are distributed in regions which appear as euchromatin in C-banded chromosomes. Sequence variation in this family is equivalent (14%–16%) at all levels of taxonomic comparison from within a population to between species. However, contiguous repeats demonstrate a much lower level of variation (9%). These, and other data, indicate that the concept of sequence homogeneity within a family of highly repeated sequences must be qualified with respect to the extensive variation between members of a given family. Comparison of the data for the 185 bp family with those from a study of a second highly repeated family, from the same taxon, demonstrates divergent patterns of evolution. Thus, the 185 bp repeats show much greater sequence variation, as well as a seemingly random pattern of incorporation of base pair alterations. The factors which may contribute to the observed pattern of variation include the time since the sequence family originated, its cytological distribution, the frequency of unequal crossing over and gene conversion and natural selection.