C-terminal sequencing by mass spectrometry: application to gelatine-derived proline-rich peptides

Protonated peptides derived from proline‐rich proteins (PRP) are often difficult to sequence by standard collision‐induced dissociation (CID) mass spectrometry (MS) due to preferential amide bond cleavage N‐terminal to proline. In connection with bovine spongiform encephalopathy regulations, proteolytic products derived from the PRP collagen have been suggested as markers for contamination of animal feedstuffs with processed animal protein (Fernandez Ocaña, M. et al., Analyst 2004, 129, 111–115). Herein, we report the identification of these marker peptides using the strategy of C‐terminal sequencing by CID MS from their sodium and lithium adducts. Upon fragmentation a new cationized peptide was produced that is one C‐terminal amino acid shorter in length. This dissociation pathway allowed for the facile identification of the C‐terminal residue by matrix‐assisted laser desorption/ionization tandem time‐of‐flight mass spectrometry. Each newly formed cationized peptide was further fragmented by up to seven stages of electrospray ionization ion trap MS. Proline‐rich C‐terminal sequence tags were established which permitted successful database identification of collagen alpha type I proteins.     

Impaired flight ability--a cost of reproduction in female blue tits

When prey are attacked by predators, escape ability has an obvious influence on the probability of survival. Laboratory studieshave suggested that flight performance of female birds mightbe affected by egg production. This is the first study of changesin take-off ability, and thus potentially in predation risk,during reproduction in wild birds. We trapped individual maleand female blue tits repeatedly during the breeding season.Females were 14% heavier and flew 20% slower (probably as aconsequence of a lower ratio of flight muscle to body mass)during the egg-laying period than after the eggs had hatched.However, flight muscle size did not change to compensate for changes in body mass over this period. In contrast, males showedno changes in either body mass, muscle size, or flight abilityover the same period. Furthermore, the impairment of flightin females increased with the proportion of the clutch thathad been laid, an effect that was independent of body mass and muscle size. This indicates that egg production causes additional physiological changes in the female body that produce impairedlocomotor performance. We suggest that courtship feeding offemale blue tits by their mates might reduce predation riskduring the period when female take-off ability is impairedby reducing the time females have to spend foraging and thusreducing the time they are exposed to increased predation.     

Comparison of dispersal ability between the green leafhoppers,Nephotettix virescens andN. cincticeps (hemiptera: Cicadellidae) by tethered flight

Dispersal propensity of green leafhoppers was compared between a tropical species, Nephotettix virescens, and a temperate species, N. cincticeps. The flight ability was measured with tethered flight technique under laboratory conditions (25°C, 16L-8D). The pre-flight period was shorter and the flight duration was longer in N. virescens than in N. cincticeps in both sexes. No significant correlations were found between the flight activity and morphometric characters for either of the two species. The results suggested that dispersal propensity of N. virescens is higher than that of N. cincticeps.     

Effect of deltamethrin-incorporated nets on mobility and survivorship of Halyomorpha halys (Hemiptera: Pentatomidae) adults and nymphs in the laboratory

The brown marmorated stink bug, Halyomorpha halys Stål (Hemiptera: Pentatomidae), is an invasive pest that attacks specialty and row crops in North America and Europe. There has been a concerted effort to reduce frequent broad-spectrum insecticide applications made on vulnerable crops. One tool that has emerged recently is the use of long-lasting insecticide-treated nets (LLINs) as a killing agent. Here, we conducted bioassays to evaluate the effect of direct contact on deltamethrin-impregnated LLINs on the behaviour and survivorship of H. halys nymphs and adults in the laboratory. Following exposure at three different durations (1.25, 4.25 or 7.25 min), vertical and horizontal mobility of adults and nymphs and the flight capacity of adults were recorded and compared with individuals that were not exposed (control). Exposure to LLINs reduced the horizontal distance and velocity and increased the angular velocity of adults only but reduced vertical mobility of adults and nymphs. Adult flights were not significantly affected by LLIN exposure. Mortality of adults and nymphs at 7-day post-exposure ranged from 73% to 77% regardless of exposure time. We discuss our findings within the context of the potential for and limitations of deploying LLINs in vulnerable crops to manage H. halys populations.     

Exploring host‐associated differentiation in the North American native cranberry fruitworm,Acrobasis vaccinii,from blueberries and cranberries

The factors explaining host‐associated differentiation (HAD) have not yet been fully characterized, especially in agricultural systems. It is thought that certain characteristics within a system may increase the probability for HAD to occur. These characteristics include relatively long‐standing evolutionary relationships between insects and their host plants, endophagy, and allochrony in host‐plant phenologies. We assessed the status of these characteristics as well as the presence of HAD in the cranberry fruitworm, Acrobasis vaccinii Riley (Lepidoptera: Pyralidae), a pest associated with blueberry and cranberry in eastern North America. We reveal the occurrence of two distinct populations of A. vaccinii that are allochronically isolated by the phenological stage of their respective host plants (cranberries or blueberries). Laboratory‐reared A. vaccinii adults collected from blueberries emerge at least 1 week earlier than adults from cranberries and the antennal sensitivity of adults to host‐plant volatiles differs between A. vaccinii collected from blueberry and cranberry. Despite finding characteristics indicative of HAD, we did not detect a genetic signature of HAD in A. vaccinii. These findings suggest that HAD may occur through behavioral and phenological mechanisms before there is sufficient genetic variation to be detected.     

食物胁迫对翅二型丽斗蟋飞行肌和繁殖发育的影响

前期研究表明,在食物充足的条件下,翅二型丽斗蟋雌成虫长、短翅型间存在着资源投入和收益的权衡关系(trade-off);而雄成虫长短翅型间不存在此类权衡关系。在自然条件下,昆虫可能遭受食物缺乏的胁迫,因而进一步就食物胁迫对丽斗蟋飞行肌和繁殖发育的影响进行了研究。结果表明,在食物胁迫的条件下,长翅雌虫仍维持飞行肌的发育,但繁殖发育受到显著的抑制;而短翅雌虫飞行肌显著降解,繁殖发育亦维持在较高水平。说明即使是营养缺乏时,其雌成虫长、短翅型也依然存在资源配置的差异,具飞行肌和繁殖发育的权衡关系。长翅雄虫飞行肌的重量与食物充足组并无显著差异,但精巢的干重显著降低;而短翅雄虫在食物胁迫条件下飞行肌显著降解,但其精巢重量与食物充足组并无显著差异。可以认为,丽斗蟋雄虫的长、短翅型间也存在飞行肌和繁殖发育的权衡关系。     

Electrophoretic variation at flight-related enzyme loci and its possible association with flight capacity inEpiphyas postvittana

Variations at three flight-related enzyme loci, -glycerophosphate dehydrogenase (-Gpdh), glucose-6-phosphate dehydrogenase (G6pd), and phosphoglucomutase (Pgm), ofEpiphyas postvittana (Walker) moths were investigated using starch gel electrophoresis. Among the three enzyme loci, -Gpdh andG6pd were found to be monomorphic, butPgm was polymorphic, with a total of seven different genotypes and five alleles identified in this study. Comparisons of allozyme variability at thePgm locus showed significant differentiation among five natural populations sampled from geographically distinct localities in New Zealand and Australia and between laboratory populations differentiated by artificial selection on flight capacity. ThePgm polymorphism was shown to be associated with the variation of flight capacity, but the role of the enzyme locus in the evolution of flight behavior is to be demonstrated in this species.This work was supported by the research scholarship of the University of New England.     

光周期对粘虫生殖与飞翔影响的初步研究

在室内恒温条件下,测定了粘虫在短光照（ＬＤ８：１６）、中等光照（ＬＤ１２：１２）、长光照（ＬＤ１６：８）、光照逐日由长变短（ＬＤ１６：８－１２：１２）和逐日由为长（ＬＤ８：１６－１２：１２）等不同光周期条件下的发育进度,生殖力和飞翔能力。结果表明,光照由长变短使幼虫发育进度比其它处理平均缩短１ｄ以上,短光照、长变知道工换短、中等光照等条件下的成虫产卵前期均比长光照。短换长和短变和等处理蛾显著延长,     

Structural evidence for co-evolution of the regulation of contraction and energy production in skeletal muscle

Skeletal muscle phosphorylase kinase (PhK) is a Ca²⁺-dependent enzyme complex, (αβγδ)₄, with the δ subunit being tightly bound endogenous calmodulin (CaM). The Ca²⁺-dependent activation of glycogen phosphorylase by PhK couples muscle contraction with glycogen breakdown in the “excitation-contraction-energy production triad.” Although the Ca²⁺-dependent protein-protein interactions among the relevant contractile components of muscle are well characterized, such interactions have not been previously examined in the intact PhK complex. Here we show that zero-length cross-linking of the PhK complex produces a covalent dimer of its catalytic γ and CaM subunits. Utilizing mass spectrometry, we determined the residues cross-linked to be in an EF hand of CaM and in a region of the γ subunit sharing high sequence similarity with the Ca²⁺-sensitive molecular switch of troponin I that is known to bind actin and troponin C, a homolog of CaM. Our findings represent an unusual binding of CaM to a target protein and supply an explanation for the low Ca²⁺ stoichiometry of PhK that has been reported. They also provide direct structural evidence supporting co-evolution of the coordinate regulation by Ca²⁺ of contraction and energy production in muscle through the sharing of a common structural motif in troponin I and the catalytic subunit of PhK for their respective interactions with the homologous Ca²⁺-binding proteins troponin C and CaM.