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1.
Pseudomonas sp. CBS3 is capable of growing with 4-chlorobenzoate as sole source of carbon and energy. The removal of the chlorine of 4-chlorobenzoate is performed in the first degradation step by an enzyme system consisting of three proteins. A 4-halobenzoate-coenzyme A ligase activates 4-chlorobenzoate in a coenzyme A, ATP and Mg2+ dependent reaction to 4-chlorobenzoyl-coenzyme A. This thioester intermediate is dehalogenated by the 4-chlorobenzoyl-coenzyme A dehalogenase. Finally coenzyme A is split off by a 4-hydroxybenzoyl-CoA thioesterase to form 4-hydroxybenzoate. The involved 4-chlorobenzoyl-coenzyme A dehalogenase was purified to apparent homogeneity by a five-step purification procedure. The native enzyme had an apparent molecular mass of 120,000 and was composed of four identical polypeptide subunits of 31 kDa. The enzyme displayed an isoelectric point of 6.7. The maximal initial rate of catalysis was achieved at pH 10 at 60 °C. The apparent K
m
value for 4-chlorobenzoyl-coenzyme A was 2.4–2.7 µM. V
max
was 1.1 × 10–7 M sec–1 (2.2 µmol min–1 mg–1 of protein). The NH2-terminal amino acid sequence was determined. All 4-halobenzoyl-coenzyme A thioesters, except 4-fluorobenzoyl-coenzyme A, were dehalogenated by the 4-chlorobenzoyl-CoA dehalogenase.Abbreviations CBA
chlorobenzoate
- CoA
coenzyme A
- HBA
hydroxybenzoate
- DTT
dithiothreitol
- HPLC
high performance liquid chromatography
- PAGE
polyacrylamide gel electrophoresis 相似文献
2.
The intermediate in the reaction catalysed by 4-chlorobenzoate dehalogenase from Pseudomonas sp. CBS3 was identified as 4-chlorobenzoyl-CoA. One component of 4-chlorobenzoate debalogenase worked as a a 4-chlorobenzoyl-CoA ligase catalysing the formation of 4-chlorobenzoyl-CoA from 4-chlorobenzoate, coenzyme A and ATP. This intermediate was detected spectrophotometrically and by HPLC. 4-chlorobenzoyl-CoA was the substrate for the dehalogenase component, which catalysed the conversion to 4-hydroxybenzoate with concomitant release or coenzyme A. 相似文献
3.
4-Chlorobenzoate:CoA ligase, the first enzyme in the pathway for 4-chlorobenzoate dissimilation, has been partially purified from Arthrobacter sp. strain TM-1, by sequential ammonium sulphate precipitation and chromatography on DEAE-Sepharose and Sephacryl S-200. The enzyme, a homodimer of subunit molecular mass approximately 56 kD, is dependent on Mg2+-ATP and coenzyme A, and produces 4-chlorobenzoyl CoA and AMP. Besides Mg2+, Mn2+, Co2+, Fe2+ and Zn2+ are also stimulatory, but not Ca2+. Maximal activity is exhibited at pH 7.0 and 25 degrees C. The ligase demonstrates broad specificity towards other halobenzoates, with 4-chlorobenzoate as best substrate. The apparent Michaelis constants (Km) of the enzyme for 4-chlorobenzoate, CoA and ATP were determined as 3.5, 30 and 238 microM respectively. 4-Chlorobenzoyl CoA dehalogenase, the second enzyme, has been purified to homogeneity by sequential column chromatography on hydroxyapatite, DEAE-Sepharose and Sephacryl S-200. It is a homotetramer of 33 kD subunits with an isoelectric point of 6.4. At pH 7.5 and 30 degrees C, Km and kcat for 4-CBCoA are 9 microM and 1 s(-1) respectively. The optimum pH is 7.5, and maximal enzymic activity occurs at 45 degrees C. The properties of this enzyme are compared with those of the 4-chlorobenzoyl CoA dehalogenases from Arthrobacter sp. strain 4-CB1 and Pseudomonas sp. strain CBS-3, which differ variously in their N-terminal amino acid sequences, optimal pH values, pI values and/or temperatures of maximal activity. 相似文献
4.
We tested the pathogenicity of 18 Metarhizium anisopliae (Metschn.) Sorokin isolates and 22 Beauveria bassiana (Balsamo) Vuillemin isolates against Alphitobius diaperinus (Panzer) (Coleoptera: Tenebrionidae) larvae and adults. The efficacy of the most virulent isolate—M. anisopliae K—was evaluated in containers with a concrete bottom covered with wood shavings, under simulated poultry house conditions.
Application of conidia of this isolate to the shavings or directly to the concrete bottom reduced the yield of larvae in 8–15
time compared with the control. In another test, the mortality of mature larvae placed on previously inoculated shavings or
bottom reached 80–90% within 14 days, compared with 14% in the control. The residual activity of conidia kept at 28°C retained
its initial level during 14 days post-inoculation, but declined after three weeks. Based on our data M. anisopliae has considerable potential for the control of A. diaperinus.
相似文献
Michael SamishEmail: Email: |
5.
Since 1985, China has established three breeding herds of Père David’s deer: the Beijing Père David’s Deer Park (39°07′N,
116°03′E), the Dafeng Père David’s Deer Nature Reserve (33°05′N, 120°49′E) and Shishou (Tianezhou) Père David’s Deer Nature
Reserve (29°49′N, 112°33′E), through reintroductions of about 30–40 founders. Since establishment, all three populations have
grown steadily. However, genetic backgrounds in those populations are still unknown. We studied the genetic diversity in Père
David’s deer and genetic consequences of population relocations in China. We revealed that genetic diversity was extremely
low in Père David’s deer populations in China. Only a single mtDNA D-loop haplotype was found in the deer, furthermore, only
five polymorphic microsatellite loci were screened out from 84 pairs of species-transferred primers. Genetic makeup in the
three Père David’s deer populations were significantly different (P < 0.01). H
E and allelic richness in the Tianezhou population were the highest (0.54, 2.60, n = 31), Beijing population (0.52, 2.4, n = 125) showed the second highest measures, while the Dafeng population (0.46, 2.39, n = 39) measured lowest. Our results suggest that effective management of a species of low genetic diversity like the Père
David’s deer should consider the genetic background of each founder to make sure genetic variations are preserved in both
source population and relocated population. Now, the Tianezhou population is the most appropriate source population in China
when establishing new Père David deer populations in the wild.
相似文献
Zhigang JiangEmail: |
6.
Five constant temperatures between 14 and 30°C were used to evaluate their effect on the development time and adult emergence
of five Trichogramma species found parasitizing eggs of the velvetbean caterpillar Anticarsia gemmatalis Hübner (Lepidoptera: Noctuidae) on soybeans in subtropical Southern Brazil. Host eggs were parasitized at 20°C and then transferred
to the study temperatures to follow development and emergence of parasitoids. All five species were able to develop and emerge
within the range of temperatures evaluated, and the effect of temperature on development rates could be described by linear
regression. Trichogramma acacioi Brun, Moraes & Soares and T. rojasi Nagaraja & Nagarkatti were the most cold-tolerant species, with lower threshold temperatures of 8.1 ± 0.16°C and 9.2 ± 0.16°C,
respectively. Trichogramma atopovirilia Oatman & Platner was the least cold-adapted species, with a lower threshold of 10.2 ± 0.13°C. Degree-day accumulation ranged
from 153.8 DD for T. atopovirilia to 190.7 DD for T. acacioi. Adult emergence was higher than 90% for T. atopovirilia and T. pretiosum at all temperatures, whereas T. lasallei Pinto emergence dropped to 71.3% at 14°C and to 58.3% at 26°C, both significantly lower than the emergence of T. pretiosum and T. atopovirilia. Significantly less T. acacioi adults emerged at 30°C than either T. pretiosum or T. atopovirilia. The sex-ratio was not affected within the range of temperatures studied, and varied from 0.65 to 0.88 (female/(male + female)).
Differences among Trichogramma spp. densities in the field can be attributed to slower development rates and/or reduced emergence of adults, both at low
and high temperatures.
相似文献
Luís A. FoersterEmail: |
7.
Carrie A. Rye Michail N. Isupov Andrey A. Lebedev Jennifer A. Littlechild 《Extremophiles : life under extreme conditions》2009,13(1):179-190
Haloacid dehalogenases have potential applications in the pharmaceutical and fine chemical industry as well as in the remediation
of contaminated land. The l-2-haloacid dehalogenase from the thermophilic archaeon Sulfolobus tokodaii has been cloned and over-expressed in Escherichia coli and successfully purified to homogeneity. Here we report the structure of the recombinant dehalogenase solved by molecular
replacement in two different crystal forms. The enzyme is a homodimer with each monomer being composed of a core-domain of
a β-sheet bundle surrounded by α-helices and an α-helical sub-domain. This fold is similar to previously solved mesophilic
l-haloacid dehalogenase structures. The monoclinic crystal form contains a putative inhibitor l-lactate in the active site. The enzyme displays haloacid dehalogenase activity towards carboxylic acids with the halide attached
at the C2 position with the highest activity towards chloropropionic acid. The enzyme is thermostable with maximum activity
at 60°C and a half-life of over 1 h at 70°C. The enzyme is relatively stable to solvents with 25% activity lost when incubated
for 1 h in 20% v/v DMSO. 相似文献
8.
The recombinant β-carotene 15,15′-monooxygenase from chicken liver was purified as a single 60 kDa band by His-Trap HP and Resource Q chromatography.
It had a molecular mass of 240 kDa by gel filtration indicating the native form to be tetramer. The enzyme converted β-carotene under maximal conditions (pH 8.0 and 37°C) with a k
cat of 1.65 min−1 and a K
m of 26 μM and its conversion yield of β-carotene to retinal was 120% (mol mol−1). The enzyme displayed catalytic efficiency and conversion yield for β-carotene, β-cryptoxanthin, β-apo-8′-carotenal, β-apo-4′-carotenal, α-carotene and γ-carotene in decreasing order but not for zeaxanthin, lutein, β-apo-12′-carotenal and lycopene, suggesting that the presence of one unsubstituted β-ionone ring in a substrate with a molecular weight greater than C30 seems to be essential for enzyme activity. 相似文献
9.
Parente A Conforto B Di Maro A Chambery A De Luca P Bolognesi A Iriti M Faoro F 《Planta》2008,228(6):963-975
The expression of type 1 ribosome-inactivating proteins (RIPs) in Phytolacca dioica L. leaves was investigated. Fully expanded leaves of young P. dioica plants (up to 3 years old) expressed two novel RIPs, dioicin 1 and dioicin 2. The former was also found in developing leaves
from adult P. dioica within about two and a half weeks after leaf development, and the latter continuously synthesized, with no seasonal or ontogenetic
constraint. Fully expanded leaves from adult P. dioica expressed four RIPs (PD-Ls1–4) exhibiting seasonal variation. RIPs were localized in the extracellular space, in the vacuole
and in the Golgi apparatus of mesophyll cells. Dioicin 1 and dioicin 2 showed rRNA N-β-glycosidase activity and displayed the following properties, respectively: (1) Mr values of 30,047.00 and 29,910.00, (2)
pIs of 8.74 and 9.37, and (3) IC50 values of 19.74 (0.658 nM) and 6.85 ng/mL (0.229 nM). Furthermore, they showed adenine polynucleotide glycosylase activity
and nicked pBR322 dsDNA. The amino acid sequence of dioicin 2 had 266 amino acid residues, and the highest percentage identity
(81.6%) and similarity (84.6%) with PAP-II from Phytolacca americana, while its identity with other RIPs from Phytolaccaceae was around 40%.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
相似文献
Augusto ParenteEmail: |
10.
Jianghong Dai Zhisheng Yu Yongzhi He Ling Zhang Zhihui Bai Zhiyang Dong Yuguo Du Hongxun Zhang 《World journal of microbiology & biotechnology》2009,25(9):1589-1595
Levoglucosan, cellulosic pyrolysate, is converted to glucose-6-phosphate by a specific levoglucosan kinase in fungi. A novel
cDNA of levoglucosan kinase gene (lgk) from yeast Lipomyces starkeyi YZ-215 was isolated by RACE method. The 1,445 bp cDNA fragment (lgk) harbouring the kinase gene exhibited one open reading frame (ORF) composed of 1,317 bp flanked by a 14 bp 5′-UTR and a 114 bp
3′-UTR, including a 25 bp poly(A) tail. The ORF encoded a 439 amino acid polypeptide with a 48.4 kDa predicted molecular mass.
Analysis of amino sequence revealed that the kinase belonged to the bacterial anhydro-N-acetylmuramic acid kinase (AnmK) family, and kinase-like proteins existed in some fungi, especially in filamentous fungi
such as Aspergillus. The kinase gene was transformed into Escherichia coli BL21 (DE3), recombinant E. coli could grow in M9 minimal medium with levoglucosan as a sole carbon source when induced by IPTG. In addition, the recombinant
kinase was overexpressed, purified and characterized. The kinase was stable at pH 7–10 and showed maximum activity at 30°C
and pH 9.0 as natural kinase, but presented higher thermostability. Kinetic constants (apparent K
m values) for LG and ATP were 105.3 ± 12.5 and 0.20 ± 0.02 mM, respectively. Furthermore, the kinase showed substrate specificity
for LG. This novel levoglucosan kinase gene would be useful in constructing recombinant microbial strains for the efficient
bioconversion of cellulosic pyrolysate to ethanol.
相似文献
Zhisheng YuEmail: |
11.
Vallejo-Becerra V Vásquez-Bahena JM Santiago-Hernández JA Hidalgo-Lara ME 《Journal of industrial microbiology & biotechnology》2008,35(11):1289-1295
The recombinant invertase INVB (re-INVB) from Zymomonas mobilis was immobilized on microbeads of Nylon-6, by means of covalent bonding. The enzyme was strongly and successfully bound to
the support. The activity of the free and immobilized enzyme was determined, using 10% (w/v) sucrose, at a temperature ranging
between 15 and 60 °C and a pH ranging between 3.5 and 7. The optimal pH and temperature for the immobilized enzyme were 5.5
and 25 °C, respectively. Immobilization of re-INVB on Nylon-6 showed no significant change in the optimal pH, but a difference
in the optimal temperature was evident, as that for the free enzyme was shown to be 40 °C. The values for kinetic parameters
were determined as: 984 and 98 mM for of immobilized and free re-INVB, respectively. values for immobilized and free enzymes were 6.1 × 102 and 1.2 × 104 s−1, respectively, and immobilized re-INVB showed of 158.73 μmol h min−1 mg−1. Immobilization of re-INVB on Nylon-6 enhanced the thermostability of the enzyme by 50% at 30 °C and 70% at 40 °C, when compared
to the free enzyme. The immobilization system reported here may have future biotechnological applications, owing to the simplicity
of the immobilization technique, the strong binding of re-INVB to the support and the effective thermostability of the enzyme. 相似文献
12.
Raif Musa-Aziz Lihong Jiang Li-Ming Chen Kevin L. Behar Walter F. Boron 《The Journal of membrane biology》2009,228(1):15-31
Others have shown that exposing oocytes to high levels of (10–20 mM) causes a paradoxical fall in intracellular pH (pHi), whereas low levels (e.g., 0.5 mM) cause little pHi change. Here we monitored pHi and extracellular surface pH (pHS) while exposing oocytes to 5 or 0.5 mM NH3/NH4
+. We confirm that 5 mM causes a paradoxical pHi fall (−ΔpHi ≅ 0.2), but also observe an abrupt pHS fall (−ΔpHS ≅ 0.2)—indicative of NH3 influx—followed by a slow decay. Reducing [NH3/NH4
+] to 0.5 mM minimizes pHi changes but maintains pHS changes at a reduced magnitude. Expressing AmtB (bacterial Rh homologue) exaggerates −ΔpHS at both levels. During removal of 0.5 or 5 mM NH3/NH4
+, failure of pHS to markedly overshoot bulk extracellular pH implies little NH3 efflux and, thus, little free cytosolic NH3/NH4
+. A new analysis of the effects of NH3 vs. NH4
+ fluxes on pHS and pHi indicates that (a) NH3 rather than NH4
+ fluxes dominate pHi and pHS changes and (b) oocytes dispose of most incoming NH3. NMR studies of oocytes exposed to 15N-labeled show no significant formation of glutamine but substantial accumulation in what is likely an acid intracellular compartment. In conclusion, parallel measurements of pHi and pHS demonstrate that NH3 flows across the plasma membrane and provide new insights into how a protein molecule in the plasma membrane—AmtB—enhances
the flux of a gas across a biological membrane.
相似文献
Walter F. Boron (Corresponding author)Email: |
13.
Subramanian Mohan Raj Chelladurai Rathnasingh Woo-Chel Jung Sunghoon Park 《Applied microbiology and biotechnology》2009,84(4):649-657
The stability and specific activity of endo-β-1,4-glucanase III from Trichoderma reesei QM9414 was enhanced, and the expression efficiency of its encoding gene, egl3, was optimized by directed evolution using error-prone PCR and activity screening in Escherichia coli RosettaBlue (DE3) pLacI as a host. Relationship between increase in yield of active enzyme in the clones and improvement
in its stability was observed among the mutants obtained in the present study. The clone harboring the best mutant 2R4 (G41E/T110P/K173M/Y195F/P201S/N218I)
selected in via second-round mutagenesis after optimal recombinating of first-round mutations produced 130-fold higher amount
of mutant enzyme than the transformant with wild-type EG III. Mutant 2R4 produced by the clone showed broad pH stability (4.4–8.8)
and thermotolerance (entirely active at 55°C for 30 min) compared with those of the wild-type EG III (pH stability, 4.4–5.2;
thermostability, inactive at 55°C for 30 min). k
cat of 2R4 against carboxymethyl-cellulose was about 1.4-fold higher than that of the wild type, though the K
m became twice of that of the wild type. 相似文献
14.
Tony Marcio da Silva Alexandre Maller André Ricardo de Lima Damásio Michele Michelin Richard John Ward Izaura Yoshico Hirata João Atilio Jorge Héctor Francisco Terenzi Maria Lourdes T. M. de Polizeli 《Journal of industrial microbiology & biotechnology》2009,36(12):1439-1446
A glucoamylase from Aspergillus niveus was produced by submerged fermentation in Khanna medium, initial pH 6.5 for 72 h, at 40°C. The enzyme was purified by DEAE-Fractogel
and Concanavalin A-Sepharose chromatography. The enzyme showed 11% carbohydrate content, an isoelectric point of 3.8 and a
molecular mass of 77 and 76 kDa estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis or Bio-Sil-Sec-400
gel filtration, respectively. The pH optimum was 5.0–5.5, and the enzyme remained stable for at least 2 h in the pH range
of 4.0–9.5. The temperature optimum was 65°C and retained 100% activity after 240 min at 60°C. The glucoamylase remained completely
active in the presence of 10% methanol and acetone. After 120 min hydrolysis of starch, glucose was the unique product formed,
confirming that the enzyme was a glucoamylase (1,4-alpha-d-glucan glucohydrolase). The K
m was calculated as 0.32 mg ml−1. Circular dichroism spectroscopy estimated a secondary structure content of 33% α-helix, 17% β-sheet and 50% random structure,
which is similar to that observed in the crystal structures of glucoamylases from other Aspergillus species. The tryptic peptide sequence analysis showed similarity with glucoamylases from A. niger, A. kawachi,
A. ficcum, A. terreus, A. awamori and A. shirousami. We conclude that the reported properties, such as solvent, pH and temperature stabilities, make A. niveus glucoamylase a potentially attractive enzyme for biotechnological applications. 相似文献
15.
This review examines the enzymes of 4-chlorobenzoate to 4-hydroxybenzoate converting pathway found in certain soil bacteria. This pathway consists of three enzymes: 4-chlorobenzoate: Coenzyme A ligase, 4-chlorobenzoyl-Coenzyme A dehalogenase and 4-hydroxybenzoyl-Coenzyme A thioesterase. Recent progress made in the cloning and expression of the pathway genes from assorted bacterial strains is described. Gene order and sequence found among these strains are compared to reveal independent enzyme recruitment strategies. Sequence alignments made between thePseudomonas sp. strain CBS3 4-chlorobenzoate pathway enzymes and structurally related proteins contained within the protein sequence data banks suggest possible origins in preexisting -oxidation pathways. The purification and characterization of the physical and kinetic properties of the pathway enzymes are described. Where possible a comparison of these properties between like enzymes from different bacterial sources are made. 相似文献
16.
Karen E. Chambers Ryan McDaniell Jeremy D. Raincrow Maya Deshmukh Peter F. Stadler 《Theorie in den Biowissenschaften》2009,128(2):109-120
Large-scale—even genome-wide—duplications have repeatedly been invoked as an explanation for major radiations. Teleosts, the
most species-rich vertebrate clade, underwent a “fish-specific genome duplication” (FSGD) that is shared by most ray-finned
fish lineages. We investigate here the Hox complement of the goldeye (Hiodon alosoides), a representative of Osteoglossomorpha, the most basal teleostean clade. An extensive PCR survey reveals that goldeye has
at least eight Hox clusters, indicating a duplicated genome compared to basal actinopterygians. The possession of duplicated Hox clusters is uncoupled to species richness. The Hox system of the goldeye is substantially different from that of other teleost lineages, having retained several duplicates
of Hox genes for which crown teleosts have lost at least one copy. A detailed analysis of the PCR fragments as well as full length
sequences of two HoxA13 paralogs, and HoxA10 and HoxC4 genes places the duplication event close in time to the divergence of Osteoglossomorpha and crown teleosts. The data are
consistent with—but do not conclusively prove—that Osteoglossomorpha shares the FSGD.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.
相似文献
Chi-hua ChiuEmail: |
17.
Danwei as a cornerstone of Chinese urban society has received great research attention. The relationship between the Danwei and psychiatric patients, however, remains unclear. This article aims to shed light on the subject with an integrated micro–macro
approach. It introduces a historical understanding of mental health in urban China under the “economic state in transition”
framework. A detailed case study in clinical sociology is provided to reveal the many social factors affecting the experience
of a schizophrenic patient and his significant others. A changing role of the Danwei is hypothesized and validated with qualitative data. The Danwei was shown to have changed significantly before the mid-1990s, yet it still played a major role in urban workers’ lives, including
those of psychiatric patients, and even more so in people’s expectations. This lends support to the need for a more responsive
public policy to address various social issues brought about by economic reform, with the learning of worldwide experiences
including “community care,” “social support” and “social rehabilitation.” Implications for social research, policymaking and
professional practice are discussed.
相似文献
Robert SévignyEmail: |
18.
Jaya Ram Simkhada Hyo Jeong Lee So Young Jang Seung Sik Cho Eun Jung Park Jae Kyung Sohng Jin Cheol Yoo 《Biotechnology letters》2009,31(3):429-435
A 60 kDa phospholipase D (PLD) was obtained from Streptomyces olivochromogenes by one-step chromatography on Sepharose CL-6B. Maximal activity was at pH 8 and 75°C and the enzyme was stable from pH 7
to 13 and from 55 to 75°C. Thermal and pH stability with temperature optimum of the enzyme were highest among Streptomyces PLDs reported so far. The activity was Ca2+-dependent and enhanced by detergents. The Km and Vmax values for phosphatidylcholine were 0.6 mM and 650 μmol min−1 mg−1, respectively. In addition, the enzyme also revealed transphosphatidylation activity, which was optimum at pH 8 and 50°C.
The first 15 amino acid residues of the N terminal sequence were ADYTPGAPGIGDPYY, which are significantly different from the
other known PLDs. The enzyme may therefore be a novel PLD with potential application in the lipid industry. 相似文献
19.
Aggregations of juvenile whale sharks (<Emphasis Type="Italic">Rhincodon typus</Emphasis>) in the Gulf of Tadjoura,Djibouti 总被引:1,自引:0,他引:1
D. Rowat M. G. Meekan U. Engelhardt B. Pardigon M. Vely 《Environmental Biology of Fishes》2007,80(4):465-472
A total of 23 whale sharks were identified over a 5 d period in the Arta Bay region of the Gulf of Tadjora, Djibouti. Most
of the sharks aggregating in this area were small (<4 m TL) males. Individuals were identified using photographs of distinctive
scars and spot and stripe patterns on the sides of the animals. Of these, 65% had scarring that was attributable to boat or
propeller strikes. Most of the whale sharks we encountered were feeding on dense accumulations of plankton in shallow water
just off (10–200 m) the shoreline. This food source may account for the aggregation of sharks in this area. One 3 m male shark
was tagged with an ARGOS (Splash) satellite tag for 9 d. During this time the shark traversed to the shoreline on the opposite
side of the Gulf (a distance of 14 km) and then returned to the Arta Bay area before retracing his path to the other shore.
The shark spent most of the daylight hours at the surface, while at night dives were more frequent, deeper and for longer
durations.
相似文献
D. RowatEmail: |
20.
Tomato is the most important vegetable crop in Spain. The mirid bug Nesidiocoris tenuis (Reuter) commonly appears in large numbers in protected and open-air tomato crops where little or no broad-spectrum insecticides
are used. Nesidiocoris tenuis is known to be a predator of whiteflies, thrips and several other pest species. However, it is also considered a pest because
it can feed on tomato plants, causing necrotic rings on stems and flowers and punctures in fruits. Our objectives were to
evaluate predation by N. tenuis on sweetpotato whitefly Bemisia tabaci Gennadius under greenhouse conditions and establish its relationship to N. tenuis feeding on tomato. Two different release rates of N. tenuis were compared with an untreated control (0, 1 and 4 N. tenuis plant−1) in cages of 8 m2. Significant reductions of greater than 90% of the whitefly population and correspondingly high numbers of N. tenuis were observed with both release rates. Regression analysis showed that necrotic rings on foliage caused by N. tenuis were best explained by the ratio of B. tabaci nymphs:N. tenuis as predicted by the equation y = 15.086x − 0.6359.
相似文献
Alberto UrbanejaEmail: |