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1.
2.
The microplasmodia of the slime mold, Physarum polycephalum, coalesce readily upon contact. The nuclei of the resulting macroplasmodia divide in synchrony approx. 6–8 h after coalescence. If prior to coalescence the microplasmodia are maintained on non-nutrient salts solution, followed by continued starvation of the resulting macroplasmodia, the nuclei also will eventually divide, although at a much later time. This mitosis occurs earlier if the starved microplasmodia are irradiated with UV light prior to coalescence. The most pronounced advancement of mitosis was found in plasmodia which were obtained by coalescence of irradiated, starved microplasmodia with non-irradiated ones.  相似文献   

3.
This experiment aimed to identify how a pig's age affected the extent and synchrony of use of different environmental enrichment materials, and how this use changed over time. Ten diverse novel objects were each presented to three replicate litters of 3 weeks of age (sucklers) and three replicate groups of three animals of 5 (weaners) weeks and 13 (growers) weeks of age. Video recordings were made of the pigs’ behaviour over a period of 5 days and subsequently analysed for activity, inactivity and object directed behaviour of three animals per group on days 1 and 5. The observed performance of any given behaviour, when at least one other member of the group was also performing that behaviour, was compared with the probability that such concurrence occurred by chance and these results were used to calculate the degree of synchronisation. Gender had no effect on the duration of object use or approach latency. Growers displayed a shorter latency to approach the objects initially compared to sucklers and weaners (mean seconds; 2153 versus 2660 versus 980 for sucklers, weaners and growers, respectively, S.E.D. 542, p = 0.007). Sucklers used the objects to a much lesser extent than either the weaners or growers (mean duration object interaction (s); 129 versus 1253 versus 1412 for sucklers, weaners and growers, respectively, S.E.D. 93, p < 0.001). Overall object use decreased between days 1 and 5 (mean duration object interaction (s); 1326 versus 536 for days 1 and 5, respectively, S.E.D. 76, p < 0.001). All of the age groups synchronised their behaviour to a much greater extent than expected by chance. The sucklers showed a higher degree of synchrony of activity (K; 0.890 versus 0.776 versus 0.682 for sucklers, weaners and growers respectively, S.E.D. 0.013, p < 0.001) and inactivity (K; 0.963 versus 0.905 versus 0.909 respectively, S.E.D. 0.007, p < 0.001), but lower degree of synchrony for object directed behaviour (K; 0.149 versus 0.375 versus 0.370 respectively, S.E.D. 0.025, p < 0.001), than the weaners and growers. The degree of synchronisation of object directed behaviour decreased over the 5-day period, irrespective of age (K; 0.382 versus 0.214 for days 1 and 5 respectively, S.E.D. 0.020, p < 0.001). Significant correlations (r = 0.678–0.879) were found between the degree of synchrony and extent of object interaction only for the sucklers. Since pigs showed behavioural synchronisation, object availability should be considered when providing desirable enrichment in order to avoid excessive competition in larger commercial groups.  相似文献   

4.
In Norway domestic sheep Ovis aries range unattended in mountainous areas during the summer season. Wolverines Gulo gulo re-established in the alpine regions of southern Norway during recent decades and are viewed as a substantial predator on lambs. Reducing predation on sheep by wolverines would not only reduce the economic loss to farmers but also promote the acceptance of wolverines in their summer ranges. We hypothesized that male lambs would be more prone to wolverine predation, because of higher locomotor activity, lower behavioural ewe–lamb synchrony and larger ewe–lamb distance. We studied ewe and lamb behavioural patterns, synchrony and ewe–lamb distance on a summer range in Knutshøi, south-central Norway. Although no differences were found in ewe–lamb distance or locomotor activity in gender, female lambs synchronized their behaviour more with their mother than males. Only for female lambs, increased synchrony resulted in closer ewe–lamb distances. Overall losses to wolverines based on long-term data indicate that male lambs are more prone to predation than females later in the season. These sex-specific behavioural differences in lambs affect the spatial and social relationships between ewe and lamb, and are likely to increase with age eventually leading to sexual segregation. Male lambs can therefore be expected to be more prone to wolverine predation towards the end of the season, when lambs become independent from the ewe.  相似文献   

5.
Poor developmental spike synchrony in wheat (Triticum aestivum L.) can reduce the effectiveness of chemical treatments keyed on reproductive events. The broadleaf herbicide (2-methyl-4-chlorophenoxy) acetic acid (MCPA) can be used to retard the development of wheat tillers if applied to winter wheat in the fall prior to the initiation of tiller primordia. Fall applications of 0.5 kg ha–1 MCPA were sufficient to reduce the tillering rate by 20–30% while providing a slight, but statistically non-significant, increase in yield. Significant increases in kernels spike–1 were observed in the MCPA treatments. The effect of MCPA on kernels spike –1 could be modulated by nitrogen fertility and planting density. A linear relationship between spike number m–2 and planting density could be observed with MCPA treatments. Reductions in total number of spikes m–2, but an increase in kernels spike–1, resulted in significant improvements in tiller synchrony. Improved tiller synchrony is important in optimizing chemical treatments where applications are based on the developmental stages of the spike. Significant reductions in plant height and subsequent reductions in lodging under high nitrogen fertility and high plant populations were observed with MCPA treatments.  相似文献   

6.
Micro/macrowire intracranial EEG (iEEG) signals recorded from implanted micro/macroelectrodes in epileptic patients have received great attention and are considered to include much information of neuron activities in seizure transition compared to scalp EEG from cortical electrodes. Microelectrode is contacted more close to neurons than macroelectrode and it is more sensitive to neuron activity changes than macroelectrode. Microwire iEEG recordings are inevitably advantageous over macrowire iEEG recordings to reveal neuronal mechanisms contributing to the generation of seizures. In this study, we investigate the seizure generation from microwire iEEG recordings and discuss synchronization of microwire iEEGs in four frequency bands: alpha (1−30 Hz), gamma (30−80 Hz), ripple (80–250 Hz), and fast ripple (>250 Hz) via two measures: correlation and phase synchrony. We find that an increase trend of correlation or phase synchrony exists before the macroseizure onset mostly in gamma and ripple bands where the duration of the preictal states varied in different seizures ranging up to a few seconds (minutes). This finding is contrast to the well-known result that a decrease of synchronization in macro domains exists before the macroseizure onset. The finding demonstrates that it is only when the seizure has recruited enough surrounding brain tissue does the signal become strong enough to be observed on the clinical macroelectrode and as a result support the hypothesis of progressive coalescence of microseizure domains. The potential ramifications of such an early detection of microscale seizure activity may open a new window on treatment by making possible disruption of seizure activity before it becomes fully established.  相似文献   

7.
Three-to-five-year population oscillations of northern small rodents are usually synchronous over hundreds of square kilometers. This regional synchrony could be due to similarity in climatic factors, or due to nomadic predators reducing the patches of high prey density close to the average density of a larger area. We estimated avian predator and small rodent densities in 4–5 predator reduction and 4–5 control areas (c. 3 km2 each) during 1989–1992 in western Finland. We studied whether nomadic avian predators concentrate at high prey density areas, and whether this decreases spatial variation in prey density. The yearly mean number of avian predator breeding territories was 0.2–1.0 in reduction areas and 3.0–8.2 in control areas. Hunting birds of prey concentrated in high prey density areas after their breeding season (August), but not necessarily during the breeding season (April to June), when they were constrained to hunt in vicinity of the nest. The experimental reduction of breeding avian predators increased variation in prey density among areas but not within areas. The difference in variation between raptor reduction and control areas was largest in the late breeding season of birds of prey, and decreased rapidly after the breeding season. These results appeared to support the hypothesis that the geographic synchrony of population cycles in small mammals may be driven by nomadic predators concentrating in high prey density areas. Predation and climatic factors apparently are complementary, rather than exclusive, factors in contributing to the synchrony.  相似文献   

8.
–Bungarotoxin (–BuTx) binds with high a.nity to the nicotinic acetylcholine receptor (AChR) of most species, mainly to sequences around the two cysteines at positions 192 and 193 of the –subunit, but other sequences of the –subunit and of the adjacent γ– or ε– and δ–subunits are also important in the native molecule. –BuTx binds strongly to human AChR but the short neurotoxins, for instance Erabutoxin B, are relatively ineffective at the human neuromuscular junction. In this article we compare the a.nity of 125I––BuTx for Torpedo and human muscle AChR and the ability of neurotoxins to inhibit this binding. We examine the contribution to –BuTx binding of the three amino acids that differ between human and Torpedo AChR –185—199. In addition, we show that an –185—199, peptide that binds strongly to 125I––BuTx and can inhibit its binding in solution, is also capable of protecting the AChR on a cell line or at the neuromuscular junction. Such peptides might be useful in the treatment of acute envenoming or the autoantibody–mediated block of AChR function that can occur in human disorders. © 1998 Elsevier Science Ltd. All rights reserved.  相似文献   

9.
Previous research has shown that after training simple discriminations (A1+/A2−, B1+/B2−), bringing these tasks under conditional control (J1–A1, J2–A2) leads to transfer of discriminative control (J1+/J2−) and to generalized matching on the basis of same discriminative functions (e.g. J1–B1, J2–B2). The same occurs when conditional discriminations are trained (D1–E1, D2–E2; F1–G1, F2–G2). When the subjects are then trained to demonstrate correct relations (D1–E1, D2–E2) when given X1 and to demonstrate incorrect relations when given X2 (XD–E), transfer of discriminative control (X1+/X2−) and generalized matching on the basis of same discriminative functions emerges (e.g. X1F1–G1, X2F1–G2). The present study investigated if these performances are dependent on the training and/or testing order. In Experiment 1, the lower-order contingency tasks were trained before the higher-order contingency tasks (A1+/A2−, B1+/B2− before J–A, and D–E, F–G before XD–E). Half the subjects received the J–B test before the more complex XF–G test (Condition A), while for the other subjects, this testing order was reversed (Condition B). Finally, all subjects received additional tests in which they were given the opportunity to demonstrate the discriminative properties of the J and X stimuli (J1+/J2−, X1+/X2−), and to match the A, J, and X stimuli with newly introduced stimuli of same discriminative properties (e.g. J1-POLITE, J2-RUDE). Experiment 2 was the same except that the training order was reversed (J–A before A1+/A2−, B1+/B2−, and XD–E before D–E, F–G). The results were affected by the training order but not by the testing order. Transfer of discriminative functions and generalized matching on the basis of same functions only occurred reliably when the lower-order contingency tasks were trained first. A stimulus-control account of the data is offered.  相似文献   

10.
Two new species of Eimeria were found from faecal samples of ten green peacocks (Pavo muticus) collected at Al-Kharj area, a central region of Saudi Arabia. Sporulated oocysts of Eimeria mutica n.sp. are ellipsoidal 23.1×17.4 (22.4–25.0×16.7–18.9) μm, with a smooth bilayered wall. A micropyle and bilobed polar body are present, but without an oocyst residuum. The sporocyst is an elongated-ovoid 13.7×6.2 (12.0–14.2×5.4–6.7) μm, with a Stieda body and a residuum. Sporulated oocysts of E. kharjensis n.sp. are subspherical 20.3×17.7 (19.0–21.5×16.2–18.7) μm, with a two layered wall and a single polar body. The micropyle is covered by a dome-shaped cap and the sporocyst is an elongate-ovoid 12.7×6.3 (11.9–13.5×5.4–6.8) μm, with a Stieda body. The sporocyst residuum is present as several small granules.  相似文献   

11.
An ‘antisense’ peptide (‘HTCA’), whose sequence was generated by reading the antisense RNA sequence corresponding to ACTH(1–24) was shown to bind ACTH(1–24) with a Kd of 0.3 nM in a solid-matrix binding assay [(1986) Biochem. J. 234, 679–683]. Two-dimensional NMR spectra were used to examine the conformational behavior in methanol and in water solution of two fragments of adrenocorticotropin, ACTH(1–24) and ACTH(1–13), as well as their antisense peptides, HTCA and HTCA(12–24). The conformations are extended chains in these solutions, both as isolated molecules and when mixed with their antisense complements. The Kd values are greater than 1 mM.  相似文献   

12.
WAY–100635 is the first selective, silent 5–HT1A (5-hydroxytryptamine1A, serotonin-1A) receptor antagonist. We have investigated the use of [3H]WAY–100635 as a quantitative autoradiographic ligand in post-mortem human hippocampus, raphe and four cortical regions, and compared it with the 5–HT1A receptor agonist, [3H]8–OH–DPAT. Saturation studies showed an average Kd for [3H]WAY–100635 binding in hippocampus of 1.1 nM. The regional and laminar distributions of [3H]WAY–100635 binding and [3H]8–OH–DPAT binding were similar. The density of [3H]WAY–100635 binding sites was 60–70% more than that of [3H]8–OH–DPAT in all areas examined except the cingulate gyrus where it was 165% higher. [3H]WAY–100635 binding was robust and was not affected by the post-mortem interval, freezer storage time or brain pH (agonal state). Using [3H]WAY–100635, we confirmed an increase of 5–HT1A receptor binding sites in the frontal cortex in schizophrenia, previously demonstrated with [3H]8–OH–DPAT. Compared to [3H]8–OH–DPAT, [3H]WAY–100635 has two advantages: it has a higher selectivity and affinity for the 5–HT1A receptor, and it recognizes 5–HT1A receptors whether or not they are coupled to a G-protein, whereas [3H]8–OH–DPAT primarily detects coupled receptors. Given these considerations, the [3H]WAY–100635 binding data in schizophrenia clarify two points. First, they indicate that the elevated [3H]8–OH–DPAT binding seen in the same cases is attributable to an increase of 5–HT1A receptors rather than any other binding site. Second, the enhanced [3H]8–OH–DPAT binding in schizophrenia reflects an increased density of 5–HT1A receptors, not an increased percentage of 5–HT1A receptors which are G-protein-coupled. We conclude that [3H]WAY–100635 is a valuable autoradiographic ligand for the qualitative and quantitative study of 5–HT1A receptors in the human brain.  相似文献   

13.
Time-resolved fluoroimmunoassay of plasma and urine O-desmethylangolensin   总被引:4,自引:0,他引:4  
We present a method for the determination of the phytoestrogen metabolite O-desmethylangolensin (O-DMA) in plasma (serum) and in urine. O-DMA is a metabolite of daidzein, which occurs in soybeans. It has been suggested that isoflavones may afford protection against breast and prostate cancer and therefore, also the metabolites are of interest. The method is based on time-resolved fluoroimmunoassay (TR–FIA) using a europium chelate as a label. After the synthesis of 4′′-O-carboxymethyl-O-DMA, this compound is coupled to bovine serum albumin, and then used as antigen in immunization of rabbits. The tracers with the europium chelate are synthesized using the same 4′′-O-derivative of the -methyldeoxybenzoin. After enzymatic hydrolysis and ether extraction the immunoassay is carried out by time resolved fluoroimmunoassay (TR–FIA). Cross-reactivity was tested with angolensin, dihydrogenistein, dihydrodaidzein, equol, 6′-OH-angolensin, trans-4-OH-equol, 6′-OH-O-DMA, cis-4-OH-equol and 5-OH-equol. The antiserum cross-reacted only with angolensin. This cross-reactivity seems not to influence the results, which were highly specific. Plasma samples are hydrolyzed and extracted. Urine samples are analyzed directly after hydrolysis without extraction. The correlation coefficient between the plasma TR–FIA results and the GC–MS results was high; r value was 0.985. The correlation coefficient between the urine TR–FIA results and the GC–MS results was high over the entire range of concentrations (0–1500 nmol/l); r value was 0.976, but lower in the low concentration range (0–100 nmol/l), i.e. value was 0.631. The intra-assay coefficients of variation (CVs) for plasma O-DMA concentrations and for urine O-DMA concentrations at three different concentrations varied 2.8–7.7 and 3.0–6.0%, respectively and the inter-assay CVs varied 3.8–8.9 and 4.4–6.6%, respectively. The working range of the plasma and urine O-DMA assays was 0.5–512 nmol/l.  相似文献   

14.
Six peptide sequences residing between basic amino acid residues in GAP were tested for effects on the release of FSH, LH and PRL in vivo in ovariectomized, estrogen-progesterone-primed (OEP) rats. Synthetic GAP peptides (1–13, 1–23, 15–23, 25–36, 38–53 and 41–53) were injected intravenously (IV) into conscious OEP rats and plasma levels of FSH, LH and PRL were measured by RIA. The activity of GAP peptides in the control of PRL was further examined in ether-stressed male rats which were injected IV with GAP peptides just prior to a 1-min etherization. GAP(1–13) significantly stimulated FSH release at doses of 1, 10 and 100 μg, whereas it stimulated LH release only at the highest dose of 100 μg. GAP(1–23) elevated plasma levels of FSH and LH only at a dose of 100 μg. The other 4 peptides had no effect on the release of gonadotropins. Of these 6 peptides, only GAP(1–13) partially lowered the plasma levels of PRL at the high dose of 100 μg in OEP rats, but it had no effect on the ether-induced PRL surge at doses of 10 and 100 μg. In conclusion, both GAP(1–13) and GAP(1–23) stimulate FSH and LH release in vivo; these 2 peptides are much less potent in stimulating gonadotropin release than is LHRH. GAP(1–13) exerts a preferential FSH-releasing activity, but its PRL-inhibiting activity is minimal.  相似文献   

15.
Tcp17 is a Trypanosoma cruzi gene located contiguous to the ABC-transporter tcpgp2. The protein contains 160 amino acid residues with a predicted molecular mass of 16.5 kDa. Western blot analysis using a polyclonal antiserum against recombinant TCP17 revealed that the protein is only expressed in the epimastigote form of the parasite; we did not detect the protein either in the amastigote or trypomastigote forms. A sequence comparison of TCP17 showed a remarkable homology with a conserved family of prokaryotic and eukaryotic proteins called YER057c whose function has not yet been characterized. Here, we propose a new signature of this family considering the N-terminal: [IV]–X(4)–[AV]–[AP]–X–[AP]–X(3)–Y–X(9)–[LIVF]–X(2)–[SA]–G–[QS], and the C-terminal: [AT]–R–X(2)–[IVFY]–X–[VC]–X(2)–L–P–X(4)–[LIVM]–E–[IVM]–[DE] motifs. Immunofluorescence and immunoelectron microscopy studies suggest that the protein has a wide distribution in the cell, with a higher concentration in the external side of the plasma membrane, on the Golgi complex and on cytoplasmic vacuoles. Although the physiological function of TCP17 is unknown, its conservation in evolution suggests biological relevance in the parasite.  相似文献   

16.
The synthesis of the 3-heptyl, and the eleven isomeric 3-methylheptyl-Δ8-tetrahydrocannabinols (3–7, R and S methyl epimers, and 8) has been carried out. The synthetic approach entailed the synthesis of substituted resorcinols, which were subjected to acid catalyzed condensation with trans-para-menthadienol to provide the Δ8-THC analogue. The 1′-, 2′- and 3′-methylheptyl analogues (3–5) are considerably more potent than Δ8-THC. The 4′-, 5′- and 6′-methylheptyl isomers (6–8) are approximately equal in potency to Δ8-THC.  相似文献   

17.
The genes coding for vegetative F plasmid replication, replication control, and incompatibility are known to map between the kilobase coordinates 40.3 and 49.3 (abbreviated 40.3–49.3F). We have subdivided this region of the F genome by a combination of in vivo and in vitro genetic techniques and have constructed F:pSC101 hybrid plasmids which contain the F DNA sequences having the approximate coordinates 41–43, 43–46, and 46–49F. We find that hybrids with regions 43–46 and 46–49F are incompatible with an F′lac+ plasmid while the hybrid with the region 41–43F is compatible. We have also constructed similar F:pSC101 hybrid plasmids with the regions 43–46 and 46–49F derived from mini-F plasmid copy number mutants. We find that hybrids made from three independent F copy number mutants show a loss of the incompatibility function associated with the 43–46F region and retention of the incompatibility function associated with 46–49F region. Moreover, spontaneous revertants, selected for regain of the 43–46F incompatibility function, have also regained normal control over their copy numbers. We also find that copy number mutations map in the 43–46F region. From our results we conclude (i) that F contains at least two inc+ loci, designated incA+ (46–49F) and incB+ (43–46F), and (ii) that gene(s) regulating F copy number may be related to the incB+ gene(s).  相似文献   

18.

Background and Aims

Self-pollination dominates in wheat, with a small level of out-crossing due to flowering asynchrony and male sterility. However, the timing and synchrony of male and female flowering in wheat is a crucial determinant of seed set and may be an important factor affecting gene flow and resilience to climate change. Here, a methodology is presented for assessing the timing and synchrony of flowering in wheat, Triticum aestivum.

Methods

From the onset of flowering until the end of anthesis, the anther and stigma activity of each floret was assessed on the first five developing ears in potted plants grown under ambient conditions and originating from ‘Paragon’ or ‘Spark-Rialto’ backgrounds. At harvest maturity, seed presence, size and weight was recorded for each floret scored.

Key Results and Conclusions

The synchrony between pollen dehiscence and stigma collapse within a flower was dependent on its relative position in a spike and within a floret. Determined on the basis of synchrony within each flower, the level of pollination by pollen originating from other flowers reached approx. 30 % and did not change throughout the duration of flowering. A modelling exercise parameterized by flowering observations indicated that the temporal and spatial variability of anther activity within and between spikes may influence the relative resilience of wheat to sudden, extreme climatic events which has direct relevance to predicted future climate scenarios in the UK.  相似文献   

19.
Iodination and immunoprecipitation techniques together with indirect fluorescent antibody tests identified two polypeptides (SP) of molecular weights 88,000–92,000 and 66,000–70,000 in the surface coat of bloodstream forms of the mouse trypanosome, Trypanosoma musculi. As parasites multiply and enter the early plateau phase of infection the 88,000–92,000 SP is present while the 66,000–70,000 SP is only detectable after the mid-plateau phase. Western blotting of parasite extracts showed that the 88,000–92,000 SP was present throughout the course of infection, but it appears to become masked by the 66,000–70,000 SP or possibly immunoglobulin from about 16 days after infection. Based on results when Western blots of parasite extracts were probed with antibodies affinity purified against the 88,000–92,000 SP, the two SP appear to be immunologically related and the smaller may be a cleavage product of the larger. This would explain why affinity purified antibodies to each SP bound to trypanosomes collected 8 days after infection, when only the 88,000–92,000 is detectable in parasite extracts. However, the failure of antibodies affinity purified against the 66,000–70,000 SP to bind to the 88,000–92,000 SP in Western blots suggests that the smaller SP has some epitopes that are immunologically distinct from those of the larger SP.  相似文献   

20.
Reaction of l-ascorbic acid with o-phenylenediamine and arylhydrazines afforded 3-(1-arylhydrazono-l-threo-2,3,4-trihydroxybutyl)-2-quinoxalinones (1–6). Whereas compounds 1–6 reacted with alkali to give 1-aryl-3-(l-threo-glycerol-1-yl)-flavazoles, the corresponding acetates (7) underwent deacetylation and rearrangement to 3-[1-aryl-5-(hydroxymethyl)pyrazol-3-yl]-2-quinoxalinones (20–24). Compounds 20–24 were also prepared from 1–5 by treatment with hot hydroxylamine hydrochloride. The action of boiling acetic anhydride on 1–5 or 7 afforded colorless products identified as the pyrazole acetates (15–19), which could also be obtained by the acetylation of compounds 20–24. Deacetylation of 15 gave 20. Oxidation of 20 with potassium permanganate gave the 5-carboxylic acid 26. The i.r., n.m.r., and mass spectra of some of these compounds are discussed.  相似文献   

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