965 resultados para Insect chemosterilization.
Resumo:
Leaf and needle biomasses are key factors in forest health. Insects that feed on needles cause growth losses and tree mortality. Insect outbreaks in Finnish forests have increased rapidly during the last decade and due to climate change the damages are expected to become more serious. There is a need for cost-efficient methods for inventorying these outbreaks. Remote sensing is a promising means for estimating forests and damages. The purpose of this study is to investigate the usability of airborne laser scanning in estimating Scots pine defoliation caused by the common pine sawfly (Diprion pini L.). The study area is situated in Ilomantsi district, eastern Finland. Study materials included high-pulse airborne laser scannings from July and October 2008. Reference data consisted of 90 circular field plots measured in May-June 2009. Defoliation percentage on these field plots was estimated visually. The study was made on plot-level and methods used were linear regression, unsupervised classification, Maximum likelihood method, and stepwise linear regression. Field plots were divided in defoliation classes in two different ways: When divided in two classes the defoliation percentages used were 0–20 % and 20–100 % and when divided in four classes 0–10 %, 10–20 %, 20–30 % and 30–100 %. The results varied depending on method and laser scanning. In the first laser scanning the best results were obtained with stepwise linear regression. The kappa value was 0,47 when using two classes and 0,37 when divided in four classes. In the second laser scanning the best results were obtained with Maximum likelihood. The kappa values were 0,42 and 0,37, correspondingly. The feature that explained defoliation best was vegetation index (pulses reflected from height > 2m / all pulses). There was no significant difference in the results between the two laser scannings so the seasonal change in defoliation could not be detected in this study.
Resumo:
Sulfotransferases (SULTs) and UDP-glucuronosyltransferases (UGTs) are important detoxification enzymes and they contribute to bioavailability and elimination of many drugs. SULT1A3 is an extrahepatic enzyme responsible for the sulfonation of dopamine, which is often used as its probe substrate. A new method for analyzing dopamine-3-O-sulfate and dopamine-4-O-sulfate by high-performance liquid chromatography was developed and the enzyme kinetic parameters for their formation were determined using purified recombinant human SULT1A3. The results show that SULT1A3 strongly favors the 3-hydroxy group of dopamine, which indicates that it may be the major enzyme responsible for the difference between the circulating levels of dopamine sulfates in human blood. All 19 known human UGTs were expressed as recombinant enzymes in baculovirus infected insect cells and their activities toward dopamine and estradiol were studied. UGT1A10 was identified as the only UGT capable of dopamine glucuronidation at a substantial level. The results were supported by studies with human intestinal and liver microsomes. The affinity was low indicating that UGT1A10 is not an important enzyme in dopamine metabolism in vivo. Despite the low affinity, dopamine is a potential new probe substrate for UGT1A10 due to its selectivity. Dopamine was used to study the importance of phenylalanines 90 and 93 in UGT1A10. The results revealed distinct effects that are dependent on differences in the size of the side chain and on the differences in their position within the protein. Examination of twelve mutants revealed lower activity in all of them. However, the enzyme kinetic studies of four mutants showed that their affinities were similar to that of UGT1A10 suggesting that F90 and F93 are not directly involved in dopamine binding in the active site. The glucuronidation of β-estradiol and epiestradiol (α-estradiol) was studied to elucidate how the orientation of the 17-OH group affects conjugation at the 3-OH or the 17-OH of either diastereomer. The results show that there are clear differences in the regio- and stereoselectivities of UGTs. The most active isoforms were UGT1A10 and UGT2B7 demonstrating opposite regioselectivity. The stereoselectivities of UGT2Bs were more complex than those of UGT1As. The amino acid sequences of the human UGTs 1A9 and 1A10 are 93% identical, yet there are large differences in their activity and substrate selectivity. Several mutants were constructed to identify the residues responsible for the activity differences. The results revealed that the residues between Leu86 and Tyr176 of UGT1A9 determine the differences between UGT1A9 and UGT1A10. Phe117 of UGT1A9 participated in 1-naphthol binding and the residues at positions 152 and 169 contributed to the higher glucuronidation rates of UGT1A10. In summary, the results emphasize that the substrate selectivities, including regio- and stereoselectivities, of UGTs are complex and they are controlled by many amino acids rather than one critical residue.
Resumo:
The role of hippuric acid formation as a mechanism for detoxication of benzoic acid in the silkworm has been investigated. Benzoate is inhibitory to the growth of the silkworm and excreted as hippuric acid, which is not toxic. Hippuric acid is not a normal constituent of excreta. Synthesis of hippuric acid has been shown to occur in the intestines of the silkworm. Hippuricase activity is present in the fat body and silk-gland tissue.
Resumo:
The variations in the activities of the alkaline and acid phosphatases of the silkworm, Bombyx mori, were studied in all stages of the life cycle. From hatching until the spinning stage a steady increase was recorded in the activity of both the enzymes followed with a conspicuous decrease at each moult. During the pupal stage the alkaline phosphatase was almost absent, whereas the acid phosphatase maintained a high and constant value. Increase or decrease of the activity of the enzymes during larval development was reflected in a decrease or increase in the acid-soluble phosphorus content. Acid phosphatase activity slowly increased from laying of the eggs to hatching of the larvae with a concomitant decrease in the acid-soluble phosphorus. Tissue analysis showed a high concentration of the alkaline enzyme in the intestines, but the haemolymph was almost free of both enzymes. Feeding of inorganic phosphate increased the alkaline enzyme in the intestines, whereas glucose had no effect on either of the enzymes in the intestines.
Resumo:
Administration of chloromycetin has been found to enhance the oxygen uptake of the gut of the silkworm. The possibility that this increase might have been due to a thinning of the gut wall has been ruled out since the reduction in gut weight set in much later. Although glucose ultilization by the gut has been found to be increased in vitro, increase in oxygen uptake has not been affected in the presence of glucose. The possibility of a hormonal stimulation has been discussed.
Resumo:
Administration of chloromycetin has been found to enhance the oxygen uptake of the gut of the silkworm. The possibility that this increase might have been due to a thinning of the gut wall has been ruled out since the reduction in gut weight set in much later. Although glucose ultilization by the gut has been found to be increased in vitro, increase in oxygen uptake has not been affected in the presence of glucose. The possibility of a hormonal stimulation has been discussed.
Resumo:
The nature and extent of the influence of chloromycetin on larval digestion and utilization of the principal dietary constituents-the proteins, fats, and minerals-was studied. The antibiotic was shown to influence favourably the utilization of all the constituents studied. The results have been discussed in the light of these and other findings.
Resumo:
The transport of glycine in vitro into the silk glands of the silkworm has been studied. Glycine accumulates inside the tissue to a concentration higher than that present outside, indicating an active transport mechanism. The kinetics of uptake show a biphasic curve and two apparent Km values for accumulation, 0.33 mM and 5.00 mM. The effect of inhibitors on the energy metabolism of glycine transport is inconclusive. Exchange studies indicate the existence of two pools inside the gland, one that is easily removed by exchange and osmotic shock, and the other which is not. The results obtained conform with the carrier model of Britten and McClure concerning the amino-acid pool in E. coli.
Resumo:
An efficient location service is a prerequisite to any robust, effective and precise location information aided Mobile Ad Hoc Network (MANET) routing protocol. Locant, presented in this paper is a nature inspired location service which derives inspiration from the insect colony framework, and it is designed to work with a host of location information aided MANET routing protocols. Using an extensive set of simulation experiments, we have compared the performance of Locant with RLS, SLS and DLS, and found that it has comparable or better performance compared to the above three location services on most metrics and has the least overhead in terms of number of bytes transmitted per location query answered.
Resumo:
GlycodelinA (GdA), a multifunctional glycoprotein secreted at high concentrations by the uterine endometrium during the early phases of pregnancy, carries glycan chains on asparagines at positions N28 and N63. GdA purified from amniotic fluid is known to be a suppressor of T-cell proliferation, an inducer of T-cell apoptosis, and an inhibitorof sperm-zona binding in contrast to its glycoform, glycodelinS (GdS), which is secreted by the seminal vesicles into the seminal plasma. The oligosaccharide chains of GdA terminate in sialic acid residues, whereas those of GdS are not sialylated but are heavily fucosylated. Our previous work has shown that the apoptogenic activity of GdA resides in the protein backbone, and we have also demonstrated the importance of sialylation for the manifestation of GdA-induced apoptosis. Recombinant glycodelin (Gd) expressed in the Sf21 insec cell line yielded an apoptotically active Gd; however, the same geneexpressed in the insect cell line Tni produced apoptotically inactive Gd, as observed with the gene expressed in the Chinese hamster ovary(CHO) cell line and earlier in Pichia pastoris. Glycan analysis of the Tni and Sf21 cell line-expressed Gd proteins reveals differences in their glycan structures, which modulate the manifestation of apoptogenic activity of Gd. Through apoptotic assays carried out with the wild-type (WT) and glycosylation mutants of Gd expressed in Sf21 and Tni cells before and after mannosidase digestion, we conclude that the accessibility to the apoptogenic region of Gd is influenced by the size of the glycans.
Resumo:
Guanylyl cyclase C (GCC) is the receptor for the family of guanylin peptides and bacterial heat-stable enterotoxins (ST). The receptor is composed of an extracellular, ligand-binding domain and an intracellular domain with a region of homology to protein kinases and a guanylyl cyclase catalytic domain. We have expressed the entire intracellular domain of GCC in insect cells and purified the recombinant protein, GCC-IDbac, to study its catalytic activity and regulation. Kinetic properties of the purified protein were similar to that of full-length GCC, and high activity was observed when MnGTP was used as the substrate. Nonionic detergents, which stimulate the guanylyl cyclase activity of membrane-associated GCC, did not appreciably increase the activity of GCC-IDbac, indicating that activation of the receptor by Lubrol involved conformational changes that required the transmembrane and/or the extracellular domain. The guanylyl cyclase activity of GCC-IDbac was inhibited by Zn2+, at concentrations shown to inhibit adenylyl cyclase, suggesting a structural homology between the two enzymes. Covalent crosslinking of GCC-IDbac indicated that the protein could associate as a dimer, but a large fraction was present as a trimer. Gel filtration analysis also showed that the major fraction of the protein eluted at a molecular size of a trimer, suggesting that the dimer detected by cross-linking represented subtle differences in the juxtaposition of the individual polypeptide chains. We therefore provide evidence that the trimeric state of GCC is catalytically active, and sequences required to generate the trimer are present in the intracellular domain of GCC.
Resumo:
The relationship between hosts and parasites is one of the most studied interactions between living organisms, and it is both universal and common in nature. Parasitoids are special type of parasites whose offspring develop attached to or within a single host organism that it ultimately consumes and kills. Hosts are arthropods and most parasitoids belong to the insect order Hymenoptera. For almost two decades metapopulation research on the Glanville fritillary butterfly (Melitaea cinxia) has been conducted in the Åland Islands, Finland. The studies have been concerned with the population dynamics, evolution, genetics, behavior, natural history and life history characteristics of M. cinxia, as well as with species interacting with the butterfly. The parasitoids of M. cinxia have been under long term studies and much has been learned about specific host-parasitoid interactions during the past decade. The research for this Master s thesis was done in the Åland Islands during summer 2010. I conducted a reciprocal transplant style experiment in order to compare the performance of host butterflies (M. cinxia) under attack by different parasitoid wasps (C. melitaearum). I used hosts and parasitoids from five origins around the Baltic Sea: Öland, Uppland, Åland, Saaremaa and Pikku-Tytärsaari. The host-parasitoid relationship was studied in terms of host susceptibility and parasitoid virulence, addressing specifically the possible effects of inbreeding and local adaptation of both parasitoids and their hosts. I compared various factors such as host defence ratio, parasitoid development rate, cocoon production rate etc. I also conducted a small scale C. melitaearum egg development experiment and C. melitaearum external morphology comparison between different parasitoid populations. The results show that host resistance and parasitoid virulence differ between both host and parasitoid populations. For example, Öland hosts were most susceptible to parasitoids and especially vulnerable to Pikku-Tytärsaari wasps. Pikku-Tytärsaari wasps were most successful in terms of parasitoids virulence and efficiency except in Saaremaa hosts, where the wasp did not succeed. Saaremaa hosts were resistant except towards Åland parasitoids. I did not find any simple pattern concerning host resistance and parasitoid virulence between inbred and outbred populations. Also, the effect of local adaptation was not detected, perhaps because metapopulation processes disturb local adaptation of the studied populations. Morphological comparisons showed differences between studied wasp populations and sexual dimorphism was obvious with females being bigger that males. There were also interesting differences among populations in male and female wing shapes. The results raise many further questions. Especially interesting were Pikku-Tytärsaari wasps that did well in terms of efficiency and virulence. Pikku-Tytärsaari is a small, isolated island in the Gulf of Finland and both the host and parasitoids are extremely inbred. For the host and parasitoid to persist in the island, the host has to have some mechanisms to escape the parasitoid. Further research will be done on the subject to discover the mechanisms of Pikku-Tytärsaari host s ability to escape parasitism. Also, genetic analyses will be conducted in the near future to determine the relatedness of used C. melitaearum populations.
Resumo:
Hyönteispölytys lisää monien ristipölytteisten viljelykasvien siemensatoa sekä parantaa sadon laatua. Marjakasveilla, kuten mansikalla ja vadelmalla marjojen koko suurenee sekä niiden laatu paranee onnistuneen pölytyksen seurauksena. Aiempien havaintojen mukaan mansikan kukat eivät pääsääntöisesti houkuttele mehiläisiä, kun taas vadelma on yksi mehiläisten pääsatokasveista. Tutkimuksen tarkoituksena oli selvittää, miten tehokkaasti mehiläiset vierailevat mansikalla sekä vadelmalla, keskittyen kukkakohtaisiin käynteihin tuntia kohti. Mehiläisiä voidaan käyttää Gliocladium catenulatum-vektoreina torjuttaessa mansikan ja vadelman harmaahometta (Botrytis cinerea). Kukkavierailujen perusteella arvioidaan, onko vektorilevitys riittävän tehokas torjumaan harmaahometta ja miten hyvin mehiläisiä voidaan käyttää pölytyspalveluihin, etenkin mansikalla. Havainnot kerättiin kuudelta eri tilalta Sisä-Savosta kesällä 2007. Kukkavierailuja laskettiin mansikan ja vadelman kukinnan aikana erilaisissa sääolosuhteissa, eri kellonaikoina ja eri etäisyyksillä mehiläispesistä. Kukat valittiin satunnaisesti, ja valintaperusteena oli kukan avonaisuus. Tarkkailuaika riippui mehiläisten lentoaktiivisuudesta. Mansikan koko havaintojakson keskiarvoksi tuli 1,75 käyntiä kukkaa kohti tunnissa. Vadelmalla vastaava luku oli 4,27, joten keskiarvojen perusteella vadelma oli houkuttelevampi kuin mansikka. Kasvukauden vaiheella ei ollut eroja vierailuihin kummallakaan kasvilla, mutta vuorokaudenajan suhteen vierailuja oli enemmän aamupäivällä kuin iltapäivällä. Lämpötila korreloi positiivisesti vierailutiheyden kanssa kummallakin kasvilla. Sääolosuhteet rajoittivat havaintojen keräämistä ja kesä oli erittäin sateinen. Mehiläiset vierailivat kukissa riittävästi haastavissakin sääolosuhteissa niin, että harmaahometorjunta onnistui. Vektorilevitystä suunnitellessa, etenkin mansikalla, tulee ottaa huomioon pesien sijoittelu sekä riittävä lukumäärä. Pesien ravinnontarpeen tulee olla suuri, jotta mehiläiset keräisivät ravintoa kukista mahdollisimman tehokkaasti. Pesiin voidaan lisätä tarvittaessa avosikiöitä tai poistaa siitepölyvarastoja ravinnonkeruuaktiivisuuden lisäämiseksi. Lisätutkimusta tarvitaan pesien sijoittelun, kilpailevien kasvien sekä mansikkalajikkeiden houkuttelevuuden vaikutuksesta vierailutiheyteen. Suomalaisten mansikkalajikkeiden meden sekä siitepölyneritystä olisi myös hyvä selvittää.
Resumo:
Experiments are performed to determine the mass and stiffness variations along the wing of the blowfly Calliphora. The results are obtained for a pairs of wings of 10 male flies and fresh wings are used. The wing is divided into nine locations along the span and seven locations along the chord based on venation patterns. The length and mass of the sections is measured and the mass per unit length is calculated. The bending stiffness measurements are taken at three locations, basal (near root), medial and distal (near tip) of the fly wing. Torsional stiffness measurements are also made and the elastic axis of the wing is approximately located. The experimental data is then used for structural modeling of the wing as a stepped cantilever beam with nine spanwise sections of varying mass per unit lengths, flexural rigidity (EI) and torsional rigidity (GJ) values. Inertial values of nine sections are found to approximately vary according to an exponentially decreasing law over the nine sections from root to tip and it is used to calculate an approximate value of Young's modulus of the wing biomaterial. Shear modulus is obtained assuming the wing biomaterial to be isotropic. Natural frequencies, both in bending and torsion, are obtained by solving the homogeneous part of the respective governing differential equations using the finite element method. The results provide a complete analysis of Calliphora wing structure and also provide guidelines for the biomimetic structural design of insect-scale flapping wings.
Resumo:
A non-occluded baculovirus, OBV-KI has been isolated from the insect pest, Oryctes rhinoceros. The viral genome is estimated to be 123 kb, with a G + C content of 43 mol% and no detectible methylated bases. A restriction map of the OBV-KI genome for BamHI, EcoRI, HindIII, PstI, SalI and XbaI has been constructed.