Electrostatic interactions between FeS clusters in NADH:ubiquinone oxidoreductase (Complex I) from Escherichia coli

The redox properties of the cofactors of NADH:ubiquinone oxidoreductase (complex I) from Escherichia coli were studied by following the changes in electron paramagnetic resonance (EPR) and optical spectra upon electrochemical redox titration of the purified protein. At neutral pH, the FMN cofactor had a midpoint redox potential ( E m) approximately -350 mV ( n = 2). Binuclear FeS clusters were well-characterized: N1a was titrated with a single ( n = 1) transition, and E m = -235 mV. In contrast, the titration of N1b can only be fitted with the sum of at least two one-electron Nernstian curves with E m values of -245 and -320 mV. The tetranuclear clusters can also be separated into two groups, either having a single, n = 1, or more complex redox titration curves. The titration curves of the EPR bands attributed to the tetranuclear clusters N2 ( g = 2.045 and g = 1.895) and N6b ( g = 2.089 and g = 1.877) can be presented by the sum of at least two components, each with E m (app) approximately -200/-300 mV and -235/-315 mV, respectively. The titration of the signals at g = 1.956-1.947 (N3 or N7, E m = -315 mV), g = 2.022, and g = 1.932 (Nx, -365 mV) and the low temperature signal at g = 1.929 (N4 or N5, -330 mV) followed Nernstian n = 1 curves. The observed redox titration curves are discussed in terms of intrinsic electrostatic interactions between FeS centers in complex I. A model showing shifts of E m due to the electrostatic interaction between the centers is presented.     

Small effective population sizes in two planktonic freshwater copepod species (Eudiaptomus) with apparently large census sizes

In small planktonic organisms, large census sizes (N(c)) suggest large effective population sizes (N(e)), but reliable estimates are rare. Here, we present N(e)/N(c) ratios for two freshwater copepod species (Eudiaptomus sp.) using temporal samples of multilocus microsatellite genotypes and a pseudo-likelihood approach. N(e)/N(c) ratios were very small in both Eudiaptomus species (10(-7)-10(-8)). Although we hypothesized that the species producing resting eggs (E. graciloides) had a larger N(e) than the other (E. gracilis), estimates were not statistically different (E. graciloides: N(e) = 672.7, CI: 276-1949; E. gracilis: N(e) = 1027.4, CI: 449-2495), suggesting that the propagule bank of E. graciloides had no detectable influence on N(e).     

Fructosamine in human and bovine semen.

We detected the presence of fructosamine in human and bovine semen. In seminal plasma of healthy normozoospermic men (N = 17) fructosamine was found in 53% of the cases (fru+). In fru+ semen samples the concentration of fructosamine was (mean +/- S.E.M., N = 9) 0.45 +/- 0.09 mmol/L and varied from 0.15 to 0.75 mmol/L. It was 3-12 times lower than in blood serum of healthy men. In semen of infertile men (N = 57) fructosamine was present only in 21% of the cases and its concentration was lower than in fertile men i.e. (mean +/- S.E.M., N = 12) 0.27 +/- 0.007 mmol/L. In bulls (N = 98) fructosamine was found in semen of 82% of animals. In fru+ semen samples the concentration of fructosamine was (mean +/- S.E.M., N = 80) 0.77 +/- 0.12 mmol/L and varied from 0.30 to 1.15 mmol/L. We did not find any correlation between the concentration of fructosamine on one hand, and that of fructose and glucose on the other hand, in either human or bull semen. The difference in the frequency of fructosamine appearance in semen of fertile and infertile men suggests that fructosamine may be in some way involved in the process of fertilisation.     

Impact of the N5-proximal Asn on the thermodynamic and kinetic stability of the semiquinone radical in photolyase

Flavoproteins can dramatically adjust the thermodynamics and kinetics of electron transfer at their flavin cofactor. A versatile regulatory tool is proton transfer. Here, we demonstrate the significance of proton-coupled electron transfer to redox tuning and semiquinone (sq) stability in photolyases (PLs) and cryptochromes (CRYs). These light-responsive proteins share homologous overall architectures and FAD-binding pockets, yet they have evolved divergent functions that include DNA repair, photomorphogenesis, regulation of circadian rhythm, and magnetoreception. We report the first measurement of both FAD redox potentials for cyclobutane pyrimidine dimer PL (CPD-PL, Anacystis nidulans). These values, E(1)(hq/sq) = -140 mV and E(2)(sq/ox) = -219 mV, where hq is FAD hydroquinone and ox is oxidized FAD, establish that the sq is not thermodynamically stabilized (ΔE = E(2) - E(1) = -79 mV). Results with N386D CPD-PL support our earlier hypothesis of a kinetic barrier to sq oxidation associated with proton transfer. Both E(1) and E(2) are upshifted by ～ 100 mV in this mutant; replacing the N5-proximal Asn with Asp decreases the driving force for sq oxidation. However, this Asp alleviates the kinetic barrier, presumably by acting as a proton shuttle, because the sq in N386D CPD-PL oxidizes orders of magnitude more rapidly than wild type. These data clearly reveal, as suggested for plant CRYs, that an N5-proximal Asp can switch on proton transfer and modulate sq reactivity. However, the effect is context-dependent. More generally, we propose that PLs and CRYs tune the properties of their N5-proximal residue to adjust the extent of proton transfer, H-bonding patterns, and changes in protein conformation associated with electron transfer at the flavin.     

Effect of intravaginal implants of melatonin on the onset of ovarian activity in adult and prepubertal ewes

Melatonin was administered intravaginally in Silastic tubing to adult and prepubertal ewes. In Exp. 1, ewe lambs (born early March) were given intravaginal melatonin implants at a mean age (+/- s.e.m.) of 7.5 +/- 0.1 weeks (Group E, N = 10) or 19.4 +/- 0.2 weeks (Group L, N = 10). The third group (Group C, N = 10) received empty implants. In Exp. 2 mature ewes were given implants on 13 May (Group E, N = 10) or 18 July (Group L, N = 10) or received empty implants (Group C, N = 10) on one of these two dates. Blood samples were taken twice weekly for progesterone assay. In Exp. 1 the mean age (+/- s.e.m.) at puberty (progesterone greater than 2 nmol/l for two consecutive samples) was 35.4 +/- 0.8 weeks. Puberty was advanced by 5.2 weeks in Group L lambs, occurring at a mean age of 30.2 +/- 0.7 weeks (P less than 0.001). In Group E lambs the timing of puberty was unaltered, occurring at a mean age of 34.8 +/- 0.6 weeks. Mature ewes in Group L (Exp. 2) showed increased incidence of ovarian activity (9/10 ewes cycling by 26 September) compared with the control ewes (1/10) (P less than 0.001), but there was no effect in Group E ewes (3/10). The results demonstrate that continuous melatonin administration to adult and prepubertal ewes can mimic the effect of short days in terms of the reproductive response, and that the present and previous exposure to melatonin is critical in determining the response.     

异色瓢虫对白毛蚜捕食作用的研究

试验研究了异色瓢虫Leis axyridis(Pallas)各龄幼虫和戌虫对白毛蚜Chaitophorus po-pulialbae无翅成蚜的捕食功能反应及其成虫的寻找效应。功能反应均属Holling II型。异色瓢虫成虫寻找效应和自身密度之间的关系用Hasell & arley(1969)模型E=QP-m 和Beddington(1975)模型E=aT/［1+btm(P-1)]进行了模拟,Beddington模型更好地反映寻找效应和瓢虫密度之间的 关系。寻找效应与瓢虫成虫自身密度和蚜虫密度之间的关系用Bcddington(1995)模型E＝aT/[1+aT_mN十bt_m(P-1)]进行描述,表明寻找效应(E)随瓢虫密度(P)和猎物蚜虫密度(N)的增大而下降     

Mechanism of the mutagenic action of hydroxylamine. IX. The UV-induced cleavage of the N-O bond in N4-hydroxy-and N4-methoxycytidine and N6-methoxyadenosine.

The principal UV-induced (lambda = 2546nm) reaction of N4-hydroxy- and N4methoxycytidines and N6-methoxyadenosine in neutral aqueous solutions is cleavage of the exocyclic N-O bond with the respective formation of cytidine and adenosine. Quantum yields are 2.8x10(-3) and 2.2x10(-3) M/E for the first two compounds and 9.1x10(-3) M/E for N6-methoxyadenosine.     

RAPD analysis of genetic diversity and population structure of Elymus sibiricus (Poaceae) native to the southeastern Qinghai-Tibet Plateau, China

Genetic diversity of Elymus sibiricus (Poaceae) was examined in eight populations from the southeast Qinghai-Tibet Plateau. We detected 291 RAPD polymorphic loci in 93 samples. The percentage of polymorphic bands (PPB) was 79%. Genetic diversity (H(E)) was 0.264, effective number of alleles (N(E)) was 1.444, Shannon's information index (H(O)) was 0.398, and expected Bayesian heterozygosity (H(B)) was 0.371. At the population level, PPB = 51%, N(E) = 1.306, H(E) = 0.176, I = 0.263, and H(B) = 0.247. A high level of genetic differentiation was detected based on Nei's genetic diversity analysis (G(ST) = 32.0%), Shannon's index analysis (33.7%), and the Bayesian method (θ(B) = 33.5%). The partitioning of molecular variance by AMOVA demonstrated significant genetic differentiation within populations (60%) and among populations (40%). The average number of individuals exchanged between populations per generation (N(m)) was 1.06. The populations were found to share high levels of genetic identity. No significant correlation was found between geographic distance and pairwise genetic distance (r = 0.7539, P = 0.9996). Correlation analysis revealed a significant correlation (r = 0.762) between RAPD H(E) found in this study and ISSR H(E) values from a previous study.     

Effects of oestradiol, zeranol or trenbolone acetate implants on puberty, reproduction and fertility in heifers

The effects of anabolic agents on reproduction in beef heifers were determined by using 300 mg trenbolone acetate (TBA), 36 mg zeranol and 19 mg oestradiol-17 beta in a biodegradable pellet (1E: American Cyanamid, USA), or two such pellets (2E). On Day 1 of experiment, 81 Hereford x Friesian heifers (mean age = 84 +/- 1.2 days) were allocated at random to the following treatments: (1) controls (N = 15); (2) TBA (N = 15); (3) 1E (N = 12); (4) 2E (N = 15); (5) zeranol (N = 13); (6) TBA + 2E (N = 11). The 1 (1E), or 2 (2E) oestradiol implants were administered on Day 1 of the experiment only. Heifers assigned to receive TBA and zeranol were implanted on Days 1, 84, 168 and 252. Blood progesterone concentrations and oestrous activity were monitored from Days 137 and 200 respectively. Mean age (days) and weight (kg) at puberty (first ovulation), for heifers that reached puberty in Groups 1-6 respectively were 352 and 308, 419 and 356, 373 and 325, 381 and 331, 400 and 353, 423 and 383 [residual standard deviation (r.s.d.) = 43.8 and 39.4 for age and weight respectively]. Heifers in Group 4 were older (P less than 0.05), but not heavier (P greater than 0.05), while those in Groups 2 and 5 were both older (P less than 0.005) and heavier (P less than 0.005) than the controls at puberty. Age and weight at puberty were not different in heifers assigned to Groups 3 and 4, or to Groups 2 and 6. The proportion of heifers showing oestrus before puberty (prepubertal oestrus) were 3/15, 12/15, 6/12, 7/15, 10/13 and 11/11 in Groups 1-6 respectively. Heifers in Groups 2 and 5 had higher incidences of prepubertal oestrus than controls, while those in other treatment groups were not different. There was no treatment effect on the incidence of silent ovulations, but the incidence of non-ovulatory oestrus, after puberty, was increased from 4/48 in Group 1 to 26/40 (P less than 0.001), 15/56 (P less than 0.05) and 34/57 (P less than 0.001) in Groups 2, 4 and 5, respectively. Heifers in Group 6 had a higher incidence of non-ovulatory oestrus (P less than 0.05), but not of prepubertal oestrus, than did those in Group 2.(ABSTRACT TRUNCATED AT 400 WORDS)     

有益真绥螨与巴氏新小绥螨的集团内捕食和同类相残作用

【目的】有益真绥螨Euseius utilis是北方地区广泛分布的一种多食性植绥螨,而巴氏新小绥螨Neoseiulus barkeri目前在我国广泛应用于农业害虫的生物防治中。本研究旨在对巴氏新小绥螨在本地的应用进行风险评估及为与有益真绥螨的联合释放提供依据。【方法】本研究在室内通过一系列实验,比较了实验室饲养的巴氏新小绥螨和采自内蒙古农业大学校园的有益真绥螨的雌成螨对同种或异种未成熟螨的捕食量、存活时间及产卵量的差异,检测了有益真绥螨与巴氏新小绥螨两种植绥螨相互之间的攻击强度以及种内和种间的相互作用。【结果】两种植绥螨都难以刺吸同种或异种植绥螨的卵,而对同种或异种植绥螨幼螨的捕食量最大,其次是对若螨。在无共同食物的情况下,有益真绥螨雌成螨对同种植绥螨幼螨的攻击性比对异种植绥螨幼螨的攻击性强(BreslowDay检验:χ~2=13.84,df=1,P0.001),且有益真绥螨对同种植绥螨幼螨的捕食量(9.10±1.65头)高于对异种植绥螨幼螨的捕食量(5.31±1.43头)(T检验:t=5.487,P0.001),巴氏新小绥螨对异种植绥螨幼螨的捕食量(7.48±0.75头)高于对同种植绥螨幼螨的捕食量(4.75±0.58头)(T检验:t=9.110,P0.05)。【结论】有益真绥螨更倾向于捕食同种幼螨而发生同类相残;巴氏新小绥螨更倾向于捕食异种幼螨而发生集团内捕食。     

Hormonal and experiential control of female-male mounting in the female rat

Mounting behavior in the female rat has been studied extensively in same-sex interactions, but not in the heterosexual dyad. The present study examined the display of female mounting of castrated noncopulating male rats (FMM). Ovariectomized (OVX) sexually naive female rats (N = 80) were given either estrogen (E) + progesterone (P), E + oil (O), P + O, or O + O treatment for five tests with castrated male rats. FMMs were observed in both the E + P and E + O females. The influence of the ovarian cycle on FMM was also investigated. Vaginal smears from sexually naive females (N = 16) were taken daily for 12 days immediately after testing with castrated males. FMM frequency was greatest during Proestrus. Finally, OVX females (N = 30) treated with E + P were given either 0, 1, 10 multi-ejaculatory heterosexual experiences with intact, sexually experienced males, prior to tests with intact, copulating or castrated, noncopulating males for five tests. Sexually naive females displayed a greater number of mounts relative to the sexually experienced females when tested with castrated, noncopulating males. In contrast, very few FMMs were observed in females of any group tested with intact, copulating males. These data suggest that FMM occurs naturally in rats as a "super-solicitational" behavior that is modified by hormone treatment and prior heterosexual experience.     

Oxygen effect in the radioresistant Escherichia coli Gamr444 strain

In experiments on E. coli Gamr 444 the oxygen effect has been studied. Cells were exposed to gamma-rays with constant bubbling of oxygen or nitrogen through the suspension or without bubbling. In the latter case the dose-effect curve was distorted due to radiochemical absorption of oxygen. The dose curve parameters were determined in the anoxic and oxygenating conditions, they are: lin n(N2) = 3.6; D0(N2) = 371 Gy; In n(O2) = 3.6; D0(O2) = 112 Gy. The oxygen effect for E. coli Gamr 444 was 3.3 as determined by D0. In studying the radiosensitivity and its modification in radioresistant strains one should eliminate the influence of radiochemical absorption of oxygen by aeration of the medium during exposure.     

Effects of trehalose polycation end-group functionalization on plasmid DNA uptake and transfection

In this study, we have synthesized six analogs of a trehalose-pentaethylenehexamine glycopolymer (Tr4) that contain (1A) adamantane, (1B) carboxy, (1C) alkynyl-oligoethyleneamine, (1D) azido trehalose, (1E) octyl, or (1F) oligoethyleneamine end groups and evaluated the effects of polymer end group chemistry on the ability of these systems to bind, compact, and deliver pDNA to cultured HeLa cells. The polymers were synthesized in one-pot azide-alkyne cycloaddition reactions with an adaptation of the Carothers equation for step-growth polymerization to produce a series of polymers with similar degrees of polymerization. An excess of end-capping monomer was added at the end of the polymerizations to maximize functionalization efficiency, which was evaluated with GPC, NMR, and MALDI-TOF. The polymers were all found to bind and compact pDNA at similarly low N/P ratios and form polyplexes with plasmid DNA. The effects of the different end group structures were most evident in the polyplex internalization and transfection assays in the presence of serum as determined by flow cytometry and luciferase gene expression, respectively. The Tr4 polymers end-capped with carboxyl groups (1B) (N/P = 7), octyne (1E) (N/P = 7), and oligoethyleneamine (1F) (N/P = 7), were taken into cells as polyplex and exhibited the highest levels of fluorescence, resulting from labeled plasmid. Similarly, the polymers end-functionalized with carboxyl groups (1E at N/P = 7), octyl groups (1E at N/P = 15), and in particular oligoethyleneamine groups (1F at N/P = 15) yielded dramatically higher reporter gene expression in the presence of serum. This study yields insight into how very subtle structural changes in polymer chemistry, such as end groups can yield very significant differences in the biological delivery efficiency and transgene expression of polymers used for pDNA delivery.     

Echinococcus multilocularis in north Italy

Alveolar echinococcosis is a zoonotic infection caused by the metacestode of the tapeworm Echinococcus multilocularis. Fox populations living in the Alpine regions of Italy had been considered free from this parasite until 2002, when two infected foxes were detected in Bolzano province (Trentino Alto Adige region) near Austrian border. A modified nested PCR analysis was used to detect E. multilocularis DNA in faecal samples belonging to red fox populations from five Italian regions. A total of 522 faecal samples were analysed from foxes shot in Valle d'Aosta (N = 65), Liguria (N = 44), Lombardy (N = 105), Veneto (N = 67), and Trentino Alto Adige (N = 241) regions. Among these, 24 samples, all from the Trentino Alto Adige region, were found positive. Moreoever, 1406 faecal samples of red foxes were analyzed by CA-ELISAs commercial test kit. This paper provides an update of the epidemiological knowledge of this parasite in north Italy.     

Experience acquisition by Trichogramma australicum Girault (Hymenoptera: Trichogrammatidae)

We investigated experience acquisition (alpha-conditioning) by females of the parasitoid Trichogramma australicum using host eggs of the noctuid moth Helicoverpa armigera (Hübner). We compared the acceptance of a host egg by females with different levels of ovipositional experience. The level of experience was designated using the standard oviposition sequence: (1) host contact (C); (2) host examination (E); (3) drilling (D); (4) full insertion (FI); and (5) oviposition (O). Each treatment consisted of a single experience level, but together these consituted a qualitative behavioural continuum of oviposition experience from naive (N) to experienced wasps. We found that host experience by adult T. australicum females can modify their behaviour. Mean duration of host finding was: N = C > E = D > FI = O. Mean duration of host examination and full insertion were: N = C > E = D = FI = O. Drilling was constant for all experience levels. Experience in drilling of the chorion during the previous host-exposure process represents a critical experience for a female and results in efficient handling and more ready acceptance of a subsequently encountered host egg.     

异叶泽兰的遗传多样性和居群历史动态研究

异叶泽兰属于菊科泽兰属,是该属分布海拔相对较高的植物,分布在青藏高原东部和横断山海拔1700～3000 m的地区.该文利用ycf6-psbM和rpl32-trnL两个叶绿体DNA(cpDNA)片段以及核DNA片段ITS(nITS)作为分子标记,研究了异叶泽兰的遗传多样性及其分布特征,探讨了其居群历史动态.结果表明:(1...     

Material properties of the ovine mitral valve anterior leaflet in vivo from inverse finite element analysis

We measured leaflet displacements and used inverse finite-element analysis to define, for the first time, the material properties of mitral valve (MV) leaflets in vivo. Sixteen miniature radiopaque markers were sewn to the MV annulus, 16 to the anterior MV leaflet, and 1 on each papillary muscle tip in 17 sheep. Four-dimensional coordinates were obtained from biplane videofluoroscopic marker images (60 frames/s) during three complete cardiac cycles. A finite-element model of the anterior MV leaflet was developed using marker coordinates at the end of isovolumic relaxation (IVR; when the pressure difference across the valve is approximately 0), as the minimum stress reference state. Leaflet displacements were simulated during IVR using measured left ventricular and atrial pressures. The leaflet shear modulus (G(circ-rad)) and elastic moduli in both the commisure-commisure (E(circ)) and radial (E(rad)) directions were obtained using the method of feasible directions to minimize the difference between simulated and measured displacements. Group mean (+/-SD) values (17 animals, 3 heartbeats each, i.e., 51 cardiac cycles) were as follows: G(circ-rad) = 121 +/- 22 N/mm2, E(circ) = 43 +/- 18 N/mm2, and E(rad) = 11 +/- 3 N/mm2 (E(circ) > E(rad), P < 0.01). These values, much greater than those previously reported from in vitro studies, may result from activated neurally controlled contractile tissue within the leaflet that is inactive in excised tissues. This could have important implications, not only to our understanding of mitral valve physiology in the beating heart but for providing additional information to aid the development of more durable tissue-engineered bioprosthetic valves.     

鼠曲草的氨基酸含量的测定及营养评价

用氨基酸分析仪测定了鼠曲草中各种氨基酸的组成,并对其进行营养评价。结果表明,鼠曲草样品(茎、花)经酸水解 处理,含有苏氨酸、缬氨酸、蛋氨酸、苯丙氨酸、异亮氨酸、亮氨酸和赖氨酸等17种氨基酸,茎中总氨基酸质量分数为18.25%、花 中为14.44%;其中包含人体必需的8种氨基酸,配比合理:E/(E+N)=0.38(茎)或0.37(花),E/N=0.62(茎)或0.59(花), 与WHO/FAO提出的E/(E+N)应为0.4左右,E/N应为0.6左右的参考蛋白质模式接近,说明鼠曲草在医学和营养学上都 有很高的研究价值,值得大力开发利用。     

Stable isotope dilution assay for prostaglandin E metabolite: 24-hour urinary output in healthy male subjects

A stable isotope dilution assay for the major urinary metabolite of prostaglandins E1 and E2 (PGE-M) was developed. After extraction and purification, the compound was converted to the dimethyl ester bis(O-methyloxime)-trimethylsilyl ether derivative and quantified with the 13C-labeled dimethyl ester analog as internal standard. The interassay coefficient of variation was 0.8%, and the intraassay coefficient of variation ranged from 0.9 to 1.7%. The recovery of authentic, underivatized PGE-M added to urine was 99.5 +/- 3.2% (mean +/- SE, N = 9). The equation of the regression curve correlating the amounts added and recovered was Y = 1.05X - 5.84, with R = 0.998. The level of excreted metabolite in healthy male subjects was 13.86 +/- 1.46 micrograms/24 h (N = 24), in good agreement with data from other sources.     

Hormonal and experiential predictors of infant survivorship and maternal behavior in a monogamous primate (Callicebus cupreus)

To better understand the roles that hormones and experience play in infant survival and maternal behavior in a biparental primate species, we analyzed urinary estrone (E(1)C) and pregnanediol glucuronide (PdG) from 24 socially housed titi monkey (Callicebus cupreus) females over 54 pregnancies (N = 1,430 samples). Pregnancies were categorized according to whether the infant survived (N = 35) or not (N = 19), and by maternal parity (primiparous: N = 9; multiparous: N = 45). Mothers of infants that survived had a significantly greater drop in PdG from the third trimester to the first week postpartum than mothers of infants that did not survive. Multiparous mothers had a greater increase in PdG from the first to the third trimester as well as greater increases in the E(1)C:PdG ratio from the first to the third trimester and from the third trimester to the first week postpartum. There were positive relationships between third trimester PdG and maternal carrying and nursing during the first week postpartum, and between maternal age and carrying during the infant's first month of life. There was a negative correlation between maternal age and PdG during the third trimester. These results suggest that elevated progesterone during late pregnancy followed by progesterone withdrawal immediately following parturition is associated with greater probability of infant survivorship and maternal behavior in this species, and that older females engage in more postpartum maternal care.