Culicoides responses to 1-octen-3-ol and carbon dioxide in salt marshes near Sea Island, Georgia, U.S.A.

Abstract. The semiochemicals carbon dioxide (CO₂) and l-octen-3-ol (octenol) were evaluated as attractants at several release rates, alone and in combination, for the major coastal species of biting midges in Georgia: Culicoides furens, C.hollensis and C.melleus (Diptera: Ceratopogonidae). The data show that CO₂ is an effective attractant for the females of all three species, but each has a different response pattern. In contrast, octenol was an effective attractant only for C.furens , either alone or in combination with CO₂; octenol had a repellent effect on the other two species. The combination of octenol and C0₂ had a synergistic effect on the collections of C.furens.     

Responses of mosquitoes of the Anopheles farauti complex to 1-octen-3-ol and light in combination with carbon dioxide in northern Queensland, Australia

Abstract. In northern Queensland, Australia, three experiments were conducted to determine the response of mosquitoes of the Anopheles farauti complex to CDC traps baited with four attractant combinations: octenol + C0₂ and light; octenol and light; CO, and light; or C0₂ and octenol without light. A CDC-modified updraft light-trap was also trialled, but did not significantly enhance collections of An.farauti sensu lato. The combination of light, octenol and C0₂ caught significantly more An.farauti s.l. (both An.farauti No. 1 and No. 2 sibling species) when compared to C0₂ and light alone. Only small numbers of the An.farauti complex were captured when CDC traps were baited with octenol alone, i.e. no light or C0₂.     

Differential responses of Aedes and Culex mosquitoes to octenol or light in combination with carbon dioxide in Queensland, Australia

Abstract. Field studies were conducted with EVS (encephalitis vector surveillance) traps in south-eastern Queensland, Australia, to determine the relative response rates of mosquitoes to three levels (0.1, 4.5 and 30mg/h) of 1-octen-3-ol (octenol) in combination with a standard bait of 2200 g carbon dioxide (CO₂), compared with CO₂ alone or CO₂ with light from a 6V incandescent bulb. Compared to CO₂ alone, Aedes vigilax collections increased significantly when CO₂ was supplemented by all three octenol emission levels, but not by the addition of light. Furthermore, the 4.5 and 30 mg/h release rate of octenol gave a significant increase in numbers of Ae.vigilax relative to that from CO₂+ light. In contrast, collections of Culex annulirostris and Culex sitiens were not enhanced significantly by either the addition of light or octenol at all three levels. Fewer Cx sitiens were collected with octenol released at 4.5 mg/h in comparison to CO₂ alone. These differential sampling rates should be taken into account when using EVS traps.     

Evaluation of the enantiomers of 1-octen-3-ol and 1-octyn-3-ol as attractants for mosquitoes associated with a freshwater swamp in Florida, U.S.A

Field studies were conducted at wooded wetlands in Gainesville, FL, U.S.A., to assess responses of natural populations of adult mosquitoes (Diptera: Culicidae) to American Biophysics MM-X and Coleman MD-2500 traps baited with enantiomers of 1-octen-3-ol, a naturally occurring compound, and 1-octyn-3-ol, a closely related synthetic compound. Overall, the same species of mosquitoes were attracted by all enantiomers, although the (R)-(+) isomer of octenol generally attracted more species, and it is the isomer produced in greatest proportion in nature. Traps baited with the R-enantiomer caught greater numbers of mosquitoes than those baited with the S-enantiomer of each compound, whereas traps baited with S-enantiomers were equally or slightly less attractive than those baited with carbon dioxide only.     

The role of 1-octen-3-ol as a host-odour attractant for the biting midge, Culicoides impunctatus Goetghebuer, and interactions of 1-octen-3-ol with a volatile pheromone produced by parous female midges

Abstract. 1-octen-3-ol, a component of the body odour of ruminants, is demonstrated to be an attractant for host-seeking, parous female Culicoides impunctatus Goetghebuer (Diptera, Ceratopogonidae).This compound was electrophysiologically and behaviourally active and, in the field, released at 0.11 ± 0.01 mg/day, increased female C.impunctatus catches over a seven-day period compared with control catches.When 1-octen-3-ol was combined either with live female midges or an extract of female midges in an electroantennogram assay, additive effects were recorded.Behaviourally, the same combination resulted in both enhanced attraction and repellency, depending on concentration.Attraction was recorded mainly when sub-threshold concentrations of the separate components were combined.The potential of such a combination as an effective field bait is discussed.     

Responses of the biting midge Culicoides impunctatus to acetone, CO2 and 1-octen-3-ol in a wind tunnel

Responses of host-seeking female Culicoides impunctatus (Goetghebuer) (Diptera: Ceratopogonidae) to acetone, carbon dioxide and 1-octen-3-ol were measured in a wind tunnel. Carbon dioxide, presented as a filamentous plume, increased upwind flight in a dose-dependent manner, up to 0.09% concentration. A homogenous CO2 plume elicited similar upwind responses at concentrations up to 0.09%, whereas higher plume concentrations (> 0.1%) induced erratic responses with a suppression of upwind flight. Bovine equivalent concentrations of acetone (1.5 x 10(-6)g/l) and 1-octen-3-ol (1.3 x 10(-8)g/) failed to induce any significant upwind response when tested alone. In the presence of CO2, however, 1-octen-3-ol showed highly significant increases in upwind responses at concentrations of 1.3 x 10(-1) - 10(-8)g/l. Mixtures of CO2+ acetone also enhanced upwind flight at 1.5 x 10(-9)g/l. High tunnel concentrations of both 1-octen-3-ol and acetone inhibited upwind responses. These findings are discussed in relation to host finding by C. impunctatus and known mechanisms by which upwind flight is initiated and arrested at high odour concentrations.     

Orientation behaviour of the blood-sucking bug triatoma infestans to short-chain fatty acids: synergistic effect of L-lactic acid and carbon dioxide

The role of short-chain fatty acids in the host-seeking behaviour of Triatoma infestans larvae was investigated using a locomotion compensator. Several short-chain fatty acids were tested alone over a wide range of doses, or in combination with L-lactic acid (L-LA; 100 microg). Bugs showed no attractive response to single carboxylic acids, but when L-LA was added to airstreams carrying specific intensities of either propionic (C3; 100 microg), butyric (C4; 1 microg) or valeric acid (C5; 1 microg), these mixtures elicited an attractive response, evincing a synergistic effect. No orientation response was observed when caproic acid (C6) was offered with L-LA at the doses tested. Two blends were created: (1) C3, C4 and C5 combined at the effective doses when added with L-LA [C3C4C5 (1)], and (2) C3, C4 and C5 combined at a third of those intensities [C3C4C5 (2)]. Both blends were tested alone, with L-LA (100 microg), with a sub-threshold concentration of CO(2) (300 p.p.m. above the ambient level), and combined with both compounds together. Oriented responses of bugs were only observed with the blend (2) added with L-LA and with the combination of this lure with CO(2). This last combination evoked a behavioural response similar in intensity to that induced by a live mouse.     

Effects of carbon dioxide, acetone and 1-octen-3-ol on the activity of the stable fly, Stomoxys calcitmns

Abstract. The responses of Stomoxys calcitrans (L.) to carbon dioxide, acetone and 1-octen-3-ol were assessed using flight activity as a measure of activation. Carbon dioxide and acetone caused significant increases in activity, with thresholds at -0.006% and -0.01 μg 1^-l, respectively. For l-octen-3-ol, flight activity decreased at 2 μg 1^-1 for males, and at 0.2 μg 1^-1 for females. Variation in activity was also manifest as differences in the time elapsed between landing and subsequent take-off: CO₂ (7.1 s) and acetone (12.2s) had lower times than the corresponding no-odour controls (16.6 and 23.2s), whereas 1-octen-3-ol (25 s) had a higher time than the control (21.5 s). The proportion of the total number of flights landing on a black target was higher in CO₂(0.16) and acetone (0.11) than in clear air (c. 0.07), but was lower for l-octen-3-ol.     

Electrophysiological and behavioural studies of the biting midge, Culicoides impunctatus Goetghebuer (Diptera, Ceratopogonidae): interactions between some plant-derived repellent compounds and a host-odour attractant, 1-octen-3-ol

Abstract. Electroantennogram (EAG) and y-tube bioassays have been used to demonstrate the repellent properties of five plant compounds with host-seeking parous female Culicoides impunctatus Goetghebuer. The compounds were methyl salicylate and allyl-, butyl-, phenyl- and 2-phenylethyl isothiocyanate. EAG thresholds were 1 times 10^-3 to 1 μg. In the bioassays, maximal repellencies occurred with 1 times 10˜² to lOug. When each compound was combined with 1-octen-3-ol, a confirmed host-odour attractant for C.impunctatus females, additive effects were recorded in EAG assays and in bioassays, all of the compounds either reduced or reversed the attractancy of l-octen-3-ol. Of the isothiocyanates, allyl isothiocyanate was the most potent and when combined with 1-octen-3-ol in field trials, the attractant effect of l-octen-3-ol was reduced.     

Effects of carbon dioxide, acetone and 1-octen-3-ol on the flight responses of the stable fly, Stomoxys calcitrans, in a wind tunnel

Abstract. The flight behaviour of Stomoxys calcitrans (L.) in odour plumes containing carbon dioxide, acetone or l-octen-3-ol was assessed from video recordings. A downwind bias was evident in clean air, whereas all three test chemicals elicited upwind anemotaxis. Response thresholds were ∼0.006% for CO2, between 0.001 and 0.01 μg/l for acetone, and ∼0.0002 u.g/1 for l-octen-3-ol. Sinuosity (° cm^-1) and angular velocity (° s^-1) increased with C0₂ concentration, but velocity (cm s"¹) decreased. Similar, but less clear effects were observed for acetone and l-octen-3-ol.     

Field studies on efficacy of host odour baits for the biting midge Culicoides impunctatus in Scotland

The efficacy of some putative attractants for the biting midge Culicoides impunctatus (Goetghebuer) (Diptera: Ceratopogonidae) was assessed using odour-baited 'delta traps' and suction traps. 1-octen-3-ol was confirmed as a potent olfactory attractant for C. impunctatus when released at 0.06mg/h. Acetone (23mg/h) and a mix of six phenolic compounds (phenol, 3-ethylphenol, 4-ethylphenol, 3-methylphenol, 4-methylphenol and 4-propylphenol), at undetermined release rate, also significantly increased delta trap catches compared to unbaited controls. When tested in combination, there was evidence of synergism between CO2 (0.2L/min) and acetone, 1-octen-3-ol or cow urine, trap catches being, respectively, 4.7, 6.2 and 9.3-fold greater than for CO2 alone. Highest catches were obtained with triple bait combinations comprising cow urine + acetone + CO2 or cow urine + 1-octen-3-ol+CO2, which increased trap catches by X 22 and X 24, respectively, compared to CO2 alone. Culicoides impunctatus was found to be extremely sensitive to CO2 and responses, gauged over two field seasons, showed a significant dose-dependent increase in catch across the entire range of release rates (0.2-2.5 L/min). Responses to these release rates, ranging from small to large mammal equivalents, emphasized the important role of CO2 in host location by C. impunctatus. Uses of olfactory attractants for monitoring and control of Culicoides are reviewed on the basis of these results.     

Assessing the eddy covariance technique for evaluating carbon dioxide exchange rates of ecosystems: past, present and future

The eddy covariance technique ascertains the exchange rate of CO₂ across the interface between the atmosphere and a plant canopy by measuring the covariance between fluctuations in vertical wind velocity and CO₂ mixing ratio. Two decades ago, the method was employed to study CO₂ exchange of agricultural crops under ideal conditions during short field campaigns. During the past decade the eddy covariance method has emerged as an important tool for evaluating fluxes of carbon dioxide between terrestrial ecosystems and the atmosphere over the course of a year, and more. At present, the method is being applied in a nearly continuous mode to study carbon dioxide and water vapor exchange at over a hundred and eighty field sites, worldwide. The objective of this review is to assess the eddy covariance method as it is being applied by the global change community on increasingly longer time scales and over less than ideal surfaces. The eddy covariance method is most accurate when the atmospheric conditions (wind, temperature, humidity, CO₂) are steady, the underlying vegetation is homogeneous and it is situated on flat terrain for an extended distance upwind. When the eddy covariance method is applied over natural and complex landscapes or during atmospheric conditions that vary with time, the quantification of CO₂ exchange between the biosphere and atmosphere must include measurements of atmospheric storage, flux divergence and advection. Averaging CO₂ flux measurements over long periods (days to year) reduces random sampling error to relatively small values. Unfortunately, data gaps are inevitable when constructing long data records. Data gaps are generally filled with values produced from statistical and empirical models to produce daily and annual sums of CO₂ exchange. Filling data gaps with empirical estimates do not introduce significant bias errors because the empirical algorithms are derived from large statistical populations. On the other hand, flux measurement errors can be biased at night when winds are light and intermittent. Nighttime bias errors tend to produce an underestimate in the measurement of ecosystem respiration. Despite the sources of errors associated with long‐term eddy flux measurements, many investigators are producing defensible estimates of annual carbon exchange. When measurements come from nearly ideal sites the error bound on the net annual exchange of CO₂ is less than ±50 g C m^?2 yr^?1. Additional confidence in long‐term measurements is growing because investigators are producing values of net ecosystem productivity that are converging with independent values produced by measuring changes in biomass and soil carbon, as long as the biomass inventory studies are conducted over multiple years.     

大气CO2浓度升高对亚洲玉米螟生长发育及繁殖的影响

大气CO2浓度升高影响寄主植物的营养而间接影响节肢动物外,还直接影响许多昆虫的生长发育和繁殖。为探讨大气CO2浓度升高对亚洲玉米螟Ostrinia furnacalis(Guenée)生长发育和繁殖的影响,在CDCC-1型密闭式动态CO2气室内研究了当前大气CO2浓度375μl/L及大气CO2浓度分别升高0.5倍和1倍,即达到550μL/L和750μL/L条件下人工饲料饲养亚洲玉米螟实验种群生命表及其营养效应指标。结果表明,大气CO2浓度分别升高到550μL/L和750μL/L时,亚洲玉米螟幼虫成活率分别降低3.0%和8.9%;幼虫、蛹和成虫体重则没有显著差异;在750μL/L CO2浓度下幼虫和蛹历期分别显著延长13.1%和25.8%。虽然单雌产卵量和净增值率(R0)在大气高CO2浓度下有增加趋势,但未达到显著性差异。与当前大气CO2浓度相比,高CO2浓度下玉米螟的取食量分别增加9.1%和34.0%,排粪量分别增加42.3%和42.0%。     

The synthesis of a DOPA analogue, 1-amino-2-(3, 4-dihydroxyphenyl)-ethylphosphonic acid and distribution studies in mice bearing the Harding-Passey melanoma

The aminophosphonic acid analogue of DOPA, DL-1-amino-2-(3,4-dihydroxy-phenyl) ethylphosphonic acid (ADEP) has been synthesised. The compound was of low toxicity; a single dose of 2 g/kg given to mice subcutaneously was not lethal.[³H]ADEP was injected subcutaneously into mice carrying the established Harding-Passey melanoma, and the distribution of the tritium determined. The highest initial concentration of radioactivity was in the kidneys, adrenal glands and eyes. Isotope content fell to low values in all tissues within 8 days or less but the tumour retained radioactivity for a longer period than did the other tissues examined.ADEP served as a substrate for mushroom tyrosinase.     

High resolution crystal structure of rat long chain hydroxy acid oxidase in complex with the inhibitor 4-carboxy-5-[(4-chlorophenyl)sulfanyl]-1, 2, 3-thiadiazole. Implications for inhibitor specificity and drug design

Long chain hydroxy acid oxidase (LCHAO) is responsible for the formation of methylguanidine, a toxic compound with elevated serum levels in patients with chronic renal failure. Its isozyme glycolate oxidase (GOX), has a role in the formation of oxalate, which can lead to pathological deposits of calcium oxalate, in particular in the disease primary hyperoxaluria. Inhibitors of these two enzymes may have therapeutic value. These enzymes are the only human members of the family of FMN-dependent l-2-hydroxy acid-oxidizing enzymes, with yeast flavocytochrome b₂ (Fcb2) among its well studied members. We screened a chemical library for inhibitors, using in parallel rat LCHAO, human GOX and the Fcb2 flavodehydrogenase domain (FDH). Among the hits was an inhibitor, CCPST, with an IC₅₀ in the micromolar range for all three enzymes. We report here the crystal structure of a complex between this compound and LCHAO at 1.3 Å resolution. In comparison with a lower resolution structure of this enzyme, binding of the inhibitor induces a conformational change in part of the TIM barrel loop 4, as well as protonation of the active site histidine. The CCPST interactions are compared with those it forms with human GOX and those formed by two other inhibitors with human GOX and spinach GOX. These compounds differ from CCPST in having the sulfur replaced with a nitrogen in the five-membered ring as well as different hydrophobic substituents. The possible reason for the ∼100-fold difference in affinity between these two series of inhibitors is discussed. The present results indicate that specificity is an issue in the quest for therapeutic inhibitors of either LCHAO or GOX, but they may give leads for this quest.     

Design,synthesis, in vitro and in vivo evaluation,and structure-activity relationship (SAR) discussion of novel dipeptidyl boronic acid proteasome inhibitors as orally available anti-cancer agents for the treatment of multiple myeloma and mechanism studies

A series of novel dipeptidyl boronic acid inhibitors of 20S proteasome were designed and synthesized. Aliphatic groups at R¹ position were designed for the first time to fully understand the SAR (structure–activity relationship). Among the screened compounds, novel inhibitor 5c inhibited the CT-L (chymotrypsin-like) activity with IC₅₀ of 8.21?nM and the MM (multiple myeloma) cells RPMI8226, U266B and ARH77 proliferations with the IC₅₀ of 8.99, 6.75 and 9.10?nM, respectively, which showed similar in vitro activities compared with the compound MLN2238 (biologically active form of marketed MLN9708). To investigate the oral availability, compound 5c was esterified to its prodrug 6a with the enzymatic IC₅₀ of 6.74?nM and RPMI8226, U266B and ARH77 cell proliferations IC₅₀ of 2.59, 4.32 and 3.68?nM, respectively. Furthermore, prodrug 6a exhibited good pharmacokinetic properties with oral bioavailability of 24.9%, similar with MLN9708 (27.8%). Moreover, compound 6a showed good microsomal stabilities and displayed stronger in vivo anticancer efficacy than MLN9708 in the human ARH77 xenograft mouse model. Finally, cell cycle results showed that compound 6a had a significant inhibitory effect on CT-L and inhibited cell cycle progression at the G2M stage.     

An investigation on 4-thiazolidinone derivatives as dual inhibitors of aldose reductase and protein tyrosine phosphatase 1B,in the search for potential agents for the treatment of type 2 diabetes mellitus and its complications

Designed multiple ligands (DMLs), developed to modulate simultaneously a number of selected targets involved in etiopathogenetic mechanisms of a multifactorial disease, such as diabetes mellitus (DM), are considered a promising alternative to combinations of drugs, when monotherapy results to be unsatisfactory. In this work, compounds 1–17 were synthesized and in vitro evaluated as DMLs directed to aldose reductase (AR) and protein tyrosine phosphatase 1B (PTP1B), two key enzymes involved in different events which are critical for the onset and progression of type 2 DM and related pathologies. Out of the tested 4-thiazolidinone derivatives, compounds 12 and 16, which exhibited potent AR inhibitory effects along with interesting inhibition of PTP1B, can be assumed as lead compounds to further optimize and balance the dual inhibitory profile. Moreover, several structural portions were identified as features that could be useful to achieve simultaneous inhibition of both human AR and PTP1B through binding to non-catalytic regions of both target enzymes.     

Stomatal sensitivities to changes in leaf water potential, air humidity, CO2 concentration and light intensity, and the effect of abscisic acid on the sensitivities in six temperate deciduous tree species

To characterise the stomata of six temperate deciduous tree species, sets of stomatal sensitivities to all the most important environmental factors were measured. To compare the importance of abscisic acid (ABA) in the different stomatal responses, the effect of exogenous ABA on all the stomatal sensitivities was determined.Almost all the stomatal sensitivities: the sensitivity to a decrease in leaf water potential, air humidity, CO₂ concentration ([CO₂]) and light intensity, and to an increase in [CO₂] and light intensity were the highest in the slow-growing species, and the lowest in the fast-growing species. Drought increased the sensitivity to the environmental changes that induce a decrease in the stomatal conductance, and decreased the sensitivity to the changes that induce an increase in this conductance. The sensitivities of the slow-growers were most strongly affected by drought and ABA. Therefore the success of the slow-growers in their ecological niches can be based on the highly sensitive and strictly regulated responses of their stomata. The fast-growers had the highest sensitivity to an increase in leaf water potential and this sensitivity was sharply reduced by drought and ABA. Thus, the dominance of the trees in riparian areas can be based on the ability of their stomata to quickly reach high conductance in well-watered conditions and to efficiently decrease this rate during drought.Stomatal sensitivities to the hydraulic environmental factors (water potentials in plant and air) had higher values in well-watered trees and a more pronounced response to drought than the sensitivities to the photosynthetic environmental factors ([CO₂] and light intensity). Thus, the hydraulic factors most likely prevail over the photosynthetic factors in determining stomatal conductance in these species.In response to exogenous ABA, the rates of stomatal closure, following a decrease in air humidity and light intensity, and an increase in [CO₂], were accelerated. Stomatal opening following an increase in air humidity and light intensity and a decrease in [CO₂] was replaced by slow closing. The rate of stomatal opening following an increase in leaf water potential was reduced. As the sensitivities to changes in light were modified less by the ABA than the other stomatal sensitivities, the prediction of stomatal responses on the basis of the sensitivity to light alone should be excluded in stomatal models.