The role of Ins(1,4,5)P(3) in signal transduction of the metabolic neuropeptide Mem-CC in the cetoniid beetle,Pachnoda sinuata

We have investigated the role of inositol triphosphate, Ins(1,4,5)P₃, in the transduction of the hypertrehalosaemic and hyperprolinaemic signal of the endogenous neuropeptide Mem-CC in the cetoniid beetle Pachnoda sinuata. Flight and injection of Mem-CC into the haemocoel of the beetle induce an increase of Ins(1,4,5)P₃ levels in the fat body of the beetle. When Mem-CC is co-injected with U 73122, which is an inhibitor of phospholipase C, this effect is abolished. Mem-CC also elevates Ins(1,4,5)P₃ concentration in fat body pieces in vitro. The increase in Ins(1,4,5)P₃ levels is tissue-specific and does not occur in brain and flight muscles. Elevation of the Ins(1,4,5)P₃ levels upon injection of Mem-CC is time- and dose-dependent: the maximum response is reached after 3 min and a dose of 10 pmol is needed. Compounds that mimic the action of cAMP (cpt-cAMP, forskolin) do not influence the concentration of Ins(1,4,5)P₃, while those that stimulate G-proteins (aluminium fluoride and cholera toxin) cause an increase of Ins(1,4,5)P₃ levels. The application (in vivo and in vitro) of F-Ins(1,4,5)P₃, an Ins(1,4,5)P₃ analogue that penetrates the cell membrane, causes a mobilisation of carbohydrate reserves via the activation of glycogen phosphorylase but does not stimulate proline synthesis. In addition, U 73122 abolishes the hypertrehalosaemic but not the hyperprolinaemic effect of Mem-CC. The results suggest that the hypertrehalosaemic signal of Mem-CC is mediated via an increase of Ins(1,4,5)P₃ levels in the fat body of P. sinuata.     

A Stilbene Optical Brightener can Enhance Bacterial Pathogenicity to Gypsy Moth (Lepidoptera: Lymantriidae) and Colorado Potato Beetle (Coleoptera: Chrysomelidae)

Stilbene optical brighteners were first investigated to protect biological control agents such as viruses, fungi, and nematodes against ultraviolet light. Some are known to enhance the activity of insect viruses in Lepidoptera. In this work, one stilbene brightener, Tinopal LPW, also increased mortality of gypsy moth and Colorado potato beetle larvae when treated with bacteria/optical brightener combinations. This increase in mortality, however, did not occur for every bacteria/insect combination. In gypsy moth, a significant increase in larval mortality was observed only with Bacillus thuringiensis combined with Tinopal LPW. In Colorado potato beetle, however, the addition of Tinopal LPW increased larval mortality with all bacteria tested (B. thuringiensis, Serratia marcescens, Photorhabdus luminescens, and Chromobacterium sp.). The brightener also decreased the time to kill for these pathogens. This decrease in LT₅₀ was observed not only for bacteria+Tinopal LPW combinations, but also for combinations of Chromobacterium sp. toxin+Tinopal LPW. The mechanism for increase in bacterial toxicity by optical brighteners is compatible with mechanisms proposed for enhancement based on viral/lepidopteran/optical brightener systems that are not dependent on replication.     

Purification and characterization of antimicrobial and vasorelaxant peptides from skin extracts and skin secretions of the North American pig frog Rana grylio

Eight peptides with differential growth–inhibitory activity against the gram-positive bacterium Staphylococcus aureus, the gram-negative bacterium Escherichia coli and the yeast, Candida albicans were isolated from an extract of the skin of the North American pig frog Rana grylio. The primary structures of these antimicrobial peptides were different from previously characterized antimicrobial peptides from Ranid frogs but on the basis of sequence similarities, the peptides may be classified as belonged to four previously characterized peptide families: the ranatuerin-1, ranatuerin-2 and ranalexin families, first identified in the North American bullfrog, Rana catesbeiana, and the temporin family first identified in the European common frog Rana temporaria. Peptides belonging to the brevinin-1, brevinin-2, esculentin-1, and esculentin-2 families, previously isolated from the skins of other species of Ranid frogs, were not identified in the extracts. The ranatuerin-1 and ranalexin peptides showed broadest spectrum of antimicrobial activity whereas the temporins were active only against S. aureus. Synthetic replicates of temporin-1Gb (SILPTIVSFLSKFL.NH₂) and temporin-1Gd (FILPLIASFLSKFL.NH₂) produced concentration-dependent relaxation of preconstricted vascular rings from the rat thoracic aorta (EC₅₀=2.4±0.1 μM for temporin-1Gb and 2.3±0.2 μM for temporin-1Gd). The antimicrobial peptides that were isolated in extracts of the skin R. grylio were present in the same molecular forms in electrically-stimulated skin secretions of the animal demonstrating that the peptides are stored in the granular glands of the skin in their fully processed forms.     

A comparative study on the isolation of adipokinetic and hypertrehalosaemic factors from insect corpora cardiaca

ABSTRACT. Extracts of corpora cardiaca from two cockroaches, Nauphoeta cinerea Olivier and Leucophaea maderae F., from a cricket, Gryllus bimaculatus De Geer, from the Colorado potato beetle, Leptinotarsa decemlineata Say, and from the sphinx moth, Sphinx ligustri L. were assayed for adipokinetic and hypertrehalosaemic activity, in acceptor locusts ( Locusta migratoria L.) and cockroaches ( Periplaneta americana L.) respectively. Both bioassays give positive results with all corpus cardiacum material tested except that from the sphinx moth; in this insect haemolymph lipid concentrations (but not those of the total carbohydrate) are, however, increased after injection of an extract of corpora cardiaca from the same species. A similar result is obtained when specimens of G. bimaculatus are injected with an extract of corpora cardiaca from G. bimaculatus. Biological activities of corpus cardiacum extracts from all species investigated can be resolved on reversed-phase high-performance liquid chromatography. Gland extracts from the two cockroach species each show a single absorbance peak which has hypertrehalosaemic activity, but with a (common) retention time distinct from all previously described arthropod neuropeptides. The corpora cardiaca of G. bimaculatus contain also a novel adipokinetic factor with a retention time distinct from previously characterized arthropod hormones, as well as from the new cockroach factor described in this study. The two hypertrehalosaemic factors from the corpora cardiaca of the potato beetle coelute with the hypertrehalosaemic hormones I and II of the American cockroach. The active (adipokinetic) compound from glands of S. ligustri appears to coelute with locust adipokinetic hormone I.     

The adipokinetic neuropeptide of Mantodea. Sequence elucidation and evolutionary relationships

A neuropeptide with adipokinetic activity in Locusta migratoria and the mantid Empusa pennata, and hypertrehalosaemic activity in Periplaneta americana, was isolated by reversed-phase high performance liquid chromatography from corpora cardiaca of the mantids E. pennata and Sphodromantis sp. After brief enzymatic digestion by 5-oxoprolylpeptidase the primary structure of the peptide of each species was determined by pulsed-liquid phase sequencing employing Edman degradation. The C-terminus of both peptides was blocked, as indicated by the lack of digestion with carboxypeptidase A. The peptides of both species were identical: a blocked, uncharged octapeptide with the sequence L-Glu-Val-Asn-Phe-Thr-Pro-Asn-Trp-NH2. The peptide is now called mantid adipokinetic hormone (Emp-AKH). The synthetic peptide was chromatographically indistinguishable from the natural compound and increased blood lipids in locusts and blood carbohydrates in cockroaches when administered in low doses. The structural features clearly define the peptide as a novel member of the large AKH/RPCH-family of peptides. Seven amino-acid residues are at identical positions in Emp-AKH when compared with the adipokinetic hormone of a dragonfly (Lia-AKH) and the hypertrehalosaemic hormone I from the American cockroach (Pea-CAH-I). Evolutionary relationships to other insect orders are discussed.     

Integration and expression of Sorghum C4 phosphoenolpyruvate carboxylase and chloroplastic NADP-malate dehydrogenase separately or together in C3 potato plants

We have integrated two cDNAs expressing Sorghum photosynthetic phosphoenolpyruvate carboxylase (C₄-PEPC) and NADP-malate dehydrogenase (cpMDH), two key enzymes involved in the primary carbon fixation pathway of NADP-malic enzyme-type C₄ plants, separately or together into a C₃ plant (potato). Analysis of the transgenic plants showed a 1.5-fold increase in PEPC and cpMDH activities compared to untransformed plants. Immunolocalization confirmed an increase at the protein level of these two enzymes in the transgenic plants and indicated that the Sorghum cpMDH was specifically addressed to the chloroplasts of potato mesophyll cells. However, integration of either or both of the cDNAs into the potato genome did not appear to significantly modify either tuber starch grain content or the rate of photosynthetic O₂ production compared to control untransformed plants. The low level of transgene expression probably explains the lack of influence on carbon metabolism and photosynthetic rates. This general observation suggests that some complex mechanism may regulate the level of production of foreign C₄ metabolism enzymes in C₃ plants.     

Isolation and identification of AKH/RPCH family peptides in blister beetles (Meloidae)

Abstract. Two peptides were isolated from methanolic extracts of corpora cardiaca of the blister beetle, Decupotoma lunata , by a single-step purification procedure, utilizing C-18 reversed-phase high-performance liquid chromatography (RP-HPLC) for separation, and the increase of haemolymph lipids in Locusta migratoria for bioassay. The native peptides were analysed by matrix-assisted laser-desorption ionization mass spectrometry revealing main ions at m/z 1180 and 1009 respectively which were attributed to the [M + Na]⁺ form of the respective peptides. After deblocking of the N-terminal pyroglutamate residue of each peptide, the structures of the deblocked peptides were determined by pulsed-liquid phase sequencing employing Edman chemistry. The sequences of the two peptides, (1) pGlu-Leu-Asn-Phe-Ser-Pro-Am-Trp-Gly-AsnNH₂ and (2) pGlu-Leu-Asn-Phe-Ser-Pro-Asn-TrpNH₂, characterize them as deca- and octapeptide members of the AKH/RPCH family. Whereas the decapeptide is a novel member of this family and is given the acronym Del-CC ( Decupotoma lunata corpus cardiacum peptide), the octapeptide has previously been found in tenebrionid beetles and has the acronym Tem-HrTH. The corpora cardiaca of two other species of blister beetles ( Cyaneolytta pectoralis and Mylabris coeca ) contain the same two peptides as D. lunata , as judged by RP-HPLC and biological activity. Neither a corpus cardiacum extract of Decupotoma lunata nor the synthetic peptides Del-CC and Tem-HrTH were active in mobilizing carbohydrates or lipids in the blister beetle.     

Sequence analyses of two neuropeptides of the AKH/RPCH-family from the lubber grasshopper, Romalea microptera

Two neuropeptides with adipokinetic activity in Locusta migratoria and hypertrehalosaemic activity in Periplaneta americana were purified by high-performance liquid chromatography from the corpus cardiacum of the lubber grasshopper, Romalea microptera. The sequences of both peptides, designated Ro I and Ro II, were determined by gas-phase sequencing employing Edman degradation after the N-terminal pyroglutamate residue was enzymatically deblocked, as well as by fast atom bombardment mass spectrometry. Ro I was found to be a decapeptide with the primary structure: pGlu-Val-Asn-Phe-Thr-Pro-Asn-Trp-Gly-Thr-NH2, whereas Ro II is an octapeptide with the structure: pGlu-Val-Asn-Phe-Ser-Thr-Gly-Trp-NH2. Ro II is identical with AKH-G isolated from the cricket Gryllus bimaculatus. Synthetic materials having the assigned structures were found to be chromatographically, mass spectrometrically, and biologically indistinguishable from the natural peptides, confirming the sequences and establishing the Romalea peptides as members of the AKH/RPCH-family of peptides.     

Variation in virulence of Beauveria bassiana isolates and its relatedness to some morphological characteristics

Ten Beauveria bassiana isolates were characterized using the following parameters: virulence, morphological measurements, germination in solid and liquid media, in vitro growth and physiological changes in liquid media. There were significant differences in mortality of second-instar larvae of the diamondback moth (DBM), Plutella xylostella (Lepidoptera: Plutellidae) and the Colorado potato beetle (CPB), Leptinotarsa decemlineata (Coleoptera, Chrysomelidae) according to isolate used (DBM; 14.51-53.37%, CPB; 25.05-74.07%). The most virulent isolates to DBM and CPB were KCF107 (soil origin) and KCF106 (Chilo suppressalis origin), respectively. Several morphological and physiological characteristics of isolates were evaluated for a possible link to virulence against both insect species. Special mean diameter (2.45-3.58 µm) and area of conidia (5.72-10.25 µm²) were significantly different among isolates. Time for 50% of conidia to germinate (GT₅₀) varied from 11 to 21 h depending on isolate. There was no correlation to virulence of size of conidia, GT_50, red pigment production and mycelial growth. Acidity of 7-day-old broth cultures of isolates was positively correlated with virulence. Iranian isolates KCF106 and KCF107 were the most promising and virulent isolates but field testing is needed to further evaluate their potential for use in DBM and CPB management.     

Consumption of O2 in the light by Chlorella pyrenoidosa and Chlamydomonas reinhardtii

A mass spectrometer has been used to measure O₂ production and consumption and net CO₂ exchange near the CO₂ compensation point in Chlorella pyrenoidosa and Chlamydomonas reinhardtii grown in air and in 2% (v/v) and 5% (v/v) CO₂ in air. Some experiments were run in presence of -hydroxy-2-pyridinemethanesulfonic acid and, for others, data are presented from parallel assays for enzymic glycolate oxidation. Although the glycolate-oxidising enzyme was present in cells grown with and without CO₂ enrichment, the activities measured were not compatible with direct measurements of O₂ consumption in the light. This and other evidence argues against glycolate being the primary substrate for light-induced O₂ consumption by these organisms.     

Volatiles released from oak, a host tree for the bark beetle Scolytus intricatus

Volatile compounds emitted in different phases of oak (Quercus robur) development (bark, unopened buds, young developing leaves, and blossoms) were analyzed with the aim of finding possible host-plant attractants for the European oak bark beetle, Scolytus intricatus. Complex mixtures of aliphatic, aromatic, and terpenoid compounds were identified in the samples. (E)-2-Hexenal and hexanal dominated in samples of bark. In buds, (Z)-3-hexenyl acetate formed a substantial part of the mixture. In both leaves and blossoms (E,E)--farnesene was the main component.

Volatiles released from oak twigs and branches during both the maturation feeding and construction of maternal galleries by Scolytus intricatus were also analyzed. Most compounds found in the samples from females’ and males’ maturation feeding were identical. High contents of anisole, (E)-β-ocimene, -copaene, one unidentified sesquiterpenic hydrocarbon C₁₅H₂₄ and β-caryophyllene were found in both samples of twigs attacked by beetles. During the construction of maternal galleries by bark beetles in oak logs, monoterpene hydrocarbons such as p-cymene, (E)-β-ocimene, and γ-terpinene, and sesquiterpenes -copaene and β-caryophyllene were released in large quantities. No new compound appeared when males were added to the log with feeding females.     

Synthesis and biological activity of adipokinetic hormone analogues modified at the C-terminus

A series of Locusta adipokinetic hormone I (AKH-I), C-terminal threonine residue using a combination of solid- and liquid-phase methodology and evaluated in Locusta migratoria, in a lipid mobilization assay in vivo and an acetate uptake assay in vitro. Modifications at Thr¹⁰ of AKH-I involved replacement of its C-terminal amide by the groups -OH, -OCH₃, -NHCH₃, -N(CH₃)₂, and -NHC₆H₅; the last three groups were also applied to the amide of AKH-I-[Thr(Brl)¹⁰]. The methyl ester, monomethyl, and dimethyl analogues were all of lower activity than the parent in the lipid mobilization assay, but lost less than two orders of potency. In the acetate uptake assay, again the methyl ester analogue showed the greatest retention of biological activity of all modified peptides. A cyclic analogue, cyclo (PLNFTPNWGT), was active in both assay, but only at very high concentrations. Almost all analogues were more active in the acetate uptake assay than in the lipid assay, but unusually, AKH-I-NHCH₃ and AKH-I-N(CH₃)₂, together with cyclo (PLNFTPNWGT), were more active in the lipid mobilization assay. In addition, the acid AKH-I analogue did not suffer as large a loss in potency in the lipid mobilization assay as in the acetate uptake assay, although it was less potent in the former. The relative potencies of these two methyl analogues contrast with those for AKH AKH-I-[Thr(Bzl)¹⁰]-NHCH₃ and AKH-I-[Thr(Bzl)¹⁰]-N(CH₃)₂, which, together with both phenyl analogues, were significantly more active in the acetate uptake assay. We conclude that the acetate uptake assay has a greater preference for a hydrophobic C-terminus, compared with the lipid mobilization assay.     

Daily Rhythms of Metabolic Rate and Body Temperature of Two Murids from Extremely Different Habitats

Daily circadian rhythms of body temperature (T_b) and oxygen consumption (VO₂) were measured in two murid species, which occupy extremely different habitats in Israel. The golden spiny mouse (Acomys mssalus) is a diurnal murid distributed in arid and hot parts of the great Syrio-African Rift Valley, while the broad-toothed field mouse (Apodeinns mystacinus) is a nocturnal species that inhabits the Mediterranean woodlands. In both species, the daily rhythms of T_b and VO₂ are entrained by the photoperiod. Under laboratory experimental conditions (ambient temperature T_a = 33^oC and photoperiod regime of 12L: 12D), Acomys russatus exhibits a tendency towards a nocturnal activity pattern, compared to the diurnal activity displayed by this species under natural conditions. Under the same photoperiod regime and at T_a = 28^oC, Apodemus mystacinus displays nocturnal activity, as observed under natural conditions. The maximal values of T_b were recorded in Acomys russatus at midnight (23:50 h), while the maximal values of VO₂ were recorded at the beginning of the dark period (18:20 h). In Apodemus mystacinus, the maximal values of T_b and VO₂ were recorded at 23:40 and 20:00 h, respectively. The ecophysiological significance of these results is discussed further.     

Respiration rhythms and heartbeats of diapausing Colorado potato beetles, Leptinotarsa decemlineata, at low temperatures

Discontinuous gas exchange cycles (DGCs), active muscular ventilation, microcycles of repetitive openings, and heartbeats of diapausing adult Colorado potato beetle, Leptinotarsa decemlineata Say (Coleoptera: Chrysomelidae), were studied at low temperatures (0, 5, and 10 °C) using an electrolytic respirometer combined with an infrared actograph. The DGC of the adult constriction-flutter-open type was the main respiration mode in fully quiescent beetles at temperatures from 5 to 10 °C. The CO₂ bursts were actively ventilated at temperatures above 5 °C. During the flutter period, a series of microcycles appeared, but no muscular contractions associated with the microcycles were detected. We identified this respiration mode as discontinuous suction ventilation.
The hydration condition of the beetles did not influence the frequency of the gas exchange cycles, but dehydrated beetles showed significantly longer flutter periods and shorter ventilation periods than hydrated beetles. The heartbeat frequencies were influenced by both temperature and hydration status.
We conclude from the results that DGCs are used at rest in adult L. decemlineata under various environmental conditions and also at low temperatures. Our results showed that DGCs are the main respiration mode of resting adult Colorado potato beetle irrespective of its hydration state and temperature. Our method resolves O₂ uptake and subsequent CO₂ release in flutter and ventilation periods and shows that diffusion is replaced by convection to reduce water loss in adult beetles.     

Infectivity of Steinernema spp. (Nematoda: Steinernematidae) to Adult Litter Beetles, Alphitobius diaperinus (Coleoptera: Tenebrionidae) in the Laboratory

Three species of Steinernema, S. carpocapsae, S. feltiae, and S. scapterisci consisting of 12 different strains, were tested for their infectivity towards adults of the litter beetle Alphitobius diaperinus. Of the five most promising nematode strains, LC₅₀ values ranged from 1.5 to 77.0 nematodes per host in the filter paper assays. Assays in poultry litter material revealed LC₅₀ values to be 5.8 and 14.6 nematodes per host for the Mexican S. carpocapsae strain and Pye S. feltiae strain.     

The methyl viologen-catalyzed mehler reaction and catalase activity in blue-green algae and Chlamydomonas reinhardi

1. The methyl viologen-catalyzed Mehler reaction was investigated in intact cells of five species of blue-green algae and Chlamydomonas reinhardi.

2. In the presence of methyl viologen, all the blue-green algae except Anabaena flos-aquae show a light-dependent O₂ consumption as well as a post-illumination O₂ evolution. The rate of O₂ consumption is stimulated by 1 mM KCN, an inhibitor of catalase, but the dark O₂ evolution becomes suppressed.

3. A. flos-aquae shows a light-dependent methyl viologen-catalyzed O₂ uptake which is not affected by 1 mM KCN. Furthermore, there is no release of O₂ in the dark following illumination.

4. With C. reinhardi, the cells do not show any net O₂ exchange during or after illumination. Addition of 1 mM KCN, however, results in an immediate O₂ uptake in the light.

5. Based on the mechanism postulated for the Mehler reaction in isolated chloroplasts, it was deduced that the differences in the kinetics of the O₂ exchange catalyzed by methyl viologen reflect differences in the endogenous catalase activity in these algae. Cells of A. flos-aquae are deficient in catalase activity whereas those of the other blue-green algae possess catalase, although at low activity. C. reinhardi, on the other hand, has high catalase activity in vivo.

6. These findings are corroborated by results obtained from O₂ electrode measurements of catalase activity in cell-free extracts of these algae.

7. The possible roles of catalase in algae and the implications of these results are also discussed.     

Influence of elevated CO2 and ozone concentrations on late blight resistance and growth of potato plants

Potato plants (Solanum tuberosum L. cv. Indira) with high susceptibility to the late blight pathogen Phytophthora infestans were exposed for 4 weeks to two different CO₂ concentrations (400/700 ppm) combined with ambient and double ambient ozone concentrations (first experiment) and with 1/5 ambient and ambient ozone concentrations (second experiment) in climate chambers. Leaves of the potato plants were then inoculated with Phytophthora infestans zoospores. Plants from the “high CO₂” variant showed a significantly increased resistance to the pathogen, verified by visual evaluation and quantitative real-time PCR, whereas plants treated with double ambient ozone were slightly more susceptible. An increase in the constitutive activities of the PR-proteins β-1,3-glucanase and osmotin in leaves of plants exposed to 700 ppm CO₂ correlated with the increase in resistance at this CO₂-concentration. Biomass parameters were barely affected by the elevated CO₂-concentration but decreased with increasing ozone concentrations. Biochemical analyses revealed that the content of starch as well as the content of soluble sugars in leaves were highest at the double ambient ozone/700 ppm CO₂ variants pointing to an ozone-induced inhibition of assimilate allocation from leaves to tubers. Leaf C/N-ratio increased at elevated CO₂-concentrations due to a decrease in N-content. The effect of the ozone- and CO₂-induced biochemical changes on the resistance response of potato towards Phytophthora infestans is discussed.     

Photostimulation of nitrogen fixation in Anabaena cylindrica

Photostimulation of N₂ fixation in the blue-green alga Anabaena cylindrica was investigated using monochromatic light and by comparing action spectra of C₂H₂ reduction with that of photosynthetic O₂ evolution. Maximum nitrogenase activity per unit energy was measured at a wavelength which corresponds to the maximum light absorption of chlorophyll a. The action spectrum of C₂H₂ reduction indicates a primary involvement of Photosystem I in N₂ fixation by blue-green algae.     

开放系统中农作物对空气CO2浓度增加的响应

FACE试验(free-air CO₂ enrichment)开展的10多年中,供试农作物主要有:C₃禾本科作物小麦(Triticum aestivum L.)、多年生黑麦草(Lolium perenne)和水稻(Oryza sativa L.),C₄禾本科类高粱(Sorghum bicolor(L.)Mench),C₃豆科植物白三叶草(Trifolium repens),C₃非禾本科块茎状作物马铃薯(Solanum tuberosum L.),以及多年生C₃类木本作物棉花(Gossypium hirsutumL.)和葡萄(Vitis viniferaL.).本文系统整理和分析了以下各项参数的结果:光合作用、气孔导度、冠层温度、水分利用、水势、叶面积指数、根茎生物量累积、作物产量、辐射利用率、比叶面积、N含量、N收益、碳水化合物含量、物候变化、土壤微生物、土壤呼吸、痕量气体交换以及土壤碳固定.CO₂浓度升高对农作物的影响作用主要表现在以下方面:(1)促进了植物光合作用、增加了其生物量累积;(2)显著提高C₃作物产量,但对C₄作物产量的影响很小;(3)降低了C₃和C₄作物气孔导度,非常显著地提高了所有作物的水分利用率;(4)对植物生长的促进作用在水分不足与水分充足时二者相当或前者大于后者;(5)对非豆科植物生长的促进作用要受到土壤低N水平限制,而对豆科植物则不受氮肥水平限制;(6)对根系生长的促进作用要大于地上部分;(7)对多年     

Transformation of steroids by Bacillus strains isolated from the foregut of water beetles (Coleoptera:Dytiscidae): I. Metabolism of androst-4-en-3,17-dione (AD)

Two Bacillus strains were isolated from the foregut of the water beetle Agabus affinis (Payk.) and tested for their steroid transforming ability. After incubation with androst-4-en-3,17-dione (AD), 13 different transformation products were detected. AD was hydroxylated at C₆, C₇, C₁₁ and C₁₄, resulting in formation of 6β-, 7-, 11- and 14-hydroxy-AD. One strain also produced small amounts of 6β,14-dihydroxy-AD. Partly, the 6β-hydroxy group was further oxidized to the corresponding 6-oxo steroids. In addition, a specific reduction of the Δ⁴-double bond was observed, leading to the formation of 5-androstane derivatives. In minor yields the carbonyl functions at C₃ and C₁₇ were reduced leading to the formation of 3ξ-OH or 17β-OH steroids. EI mass spectra of the trimethylsilyl and O-methyloxime trimethylsilyl ether derivatives of some transformation products are presented for the first time.