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1.
N. J. Belshaw S. Hakola H. Nevalainen M. Penttil? P. Suominen D. B. Archer 《Molecular & general genetics : MGG》1997,256(1):18-27
Three DNA fragments, trs1, 2 and 3, were isolated from the Trichoderma reesei genome on the basis of their ability to promote autonomous replication of plasmids in Saccharomyces cerevisiae. Each trs element bound specifically to the isolated T. reesei nuclear matrix in vitro, and two of them bound in vivo, indicating that they are matrix attachment regions (MARs). A similar
sequence previously isolated from Aspergillus nidulans (ans1) was also shown to bind specifically to the T. reesei nuclear matrix in vitro. The T. reesei MARs are AT-rich sequences containing 70%, 86% and 73% A+T over 2.9, 0.8 and 3.7 kb, respectively for trs1, 2 and 3. They exhibited no significant sequence homology, but were shown to contain a number of sequence motifs that occur frequently
in many MARs identified in other eukaryotes. However, these motifs occurred as frequently in the trs elements as in randomly generated sequences with the same A+T content. trs1 and 3 were shown to be present as single copies in the T. reesei genome. The presence of the trs elements in transforming plasmids enhanced the frequency of integrative transformation of T. reesei up to five fold over plasmids without a trs. No evidence was obtained to suggest that the trs elements promoted efficient replication of plasmids in T. reseei. A mechanism for the enhancement of transformation frequency by the trs elements is proposed.
Received: 1 March 1997 / Accepted: 13 May 1997 相似文献
2.
Geographic variation in sexual dimorphism of tooth size was assessed for the red fox Vulpes vulpes (Linnaeus, 1758) across the whole northern range of the species. Twenty-one measurements of tooth size and skull length were taken from 2849 specimens (1577 males and 1272 females) originating from 12 Nearctic and 25 Palearctic localities. The index of sexual dimorphism was calculated as a quotient of the mean measure of certain characters in males by the respective mean in females ( M m / M f ). In the whole range, the males were larger than females and mean dimorphism index of tooth size ranged from 1.01 to 1.06. On average, the tooth measurements in males were 3.6% larger than in females. The highest dimorphism was observed in the canines. Dimorphism of tooth size was higher in the Palearctic than Nearctic. Statistically significant differences between regions were found for lengths of C1 , C1 and M1 . In the Palearctic, higher values of the dimorphism indices were observed particularly in the southern parts of the Eurasian range of the red fox and in Great Britain. For a few metrical traits, sexual dimorphism indices presented significant relations to some geo-climatic variables. The geographic pattern of size dimorphism in the red fox seems to be shaped by sexual selection, intraspecific and interspecific competition and population density. 相似文献
3.
R.J. Dobson A.P. Dargantes R.T. Mercado 《International journal for parasitology》2009,39(10):1115-1123
Simple demographic and infectious disease models of buffaloes and other domestic hosts for animal trypanosomosis (surra) caused by Trypanosoma evansi were developed. The animal models contained deterministic and stochastic elements and were linked to simulate the benefit of control regimes for surra in village domestic animal populations in Mindanao, Philippines. The impact of the disease on host fertility and mortality were key factors in determining the economic losses and net-benefit from the control regimes. If using a high (99%) efficacy drug in surra-moderate to high risk areas, then treating all animals twice each year yielded low prevalence in 2 years; targeted treatment of clinically sick animals, constantly monitored (monthly), required 75% fewer treatments but took longer to reach a low prevalence than treating all animals twice each year. At high drug efficacy both of these treatment strategies increased the benefit over untreated animals by 81%. If drug efficacy declined then the benefit obtained from twice yearly treatment of all animals declined rapidly compared with regular monitoring and targeting treatment to clinically sick animals. The current control regimen applied in the Philippines of annual sero-testing for surra and only treating sero-positive animals provided the lowest net-benefit of all the control options simulated and would not be regarded as effective control. The total net-benefit from effective surra control for a typical village in a moderate/high risk area was 7.9 million pesos per annum (US $158,000). The value added to buffaloes, cattle, horses, goats/sheep and pigs as a result of this control was US $88, $84, $151, $7, $114 per animal/year, respectively. 相似文献
4.
The southeast Asian scarab beetle genus Peltonotus Burmeister (Scarabaeidae, Dynastinae, Cyclocephalini) is reviewed. New country records for Peltonotus morio Burmeister (Myanmar and Vietnam), Peltonotus nasutus Arrow (southern China and Cambodia), and Peltonotus favonius Jameson and Wada (Myanmar) are reported, including a new record in the Palearctic/Sino-Japanese biogeographic region. The first female specimen of Peltonotus favonius is described. Biological associations with aroid inflorescences are reviewed, and human consumption of Peltonotus beetles is reported. A key to all species, paralectotype designations for Peltonotus nasutus, diagnoses, and distributions using dynamic mapping tools are included. 相似文献
5.
P. S. GREWAL W. R. MARTIN R. W. MILLER E. E. LEWIS 《Biocontrol Science and Technology》1997,7(3):393-400
We studied the influence of entomopathogenic nematodes , Steinernema carpocapsae and S. riobravis, on natural populations of plant - parasitic nematodes (PPNs) infesting turfgrass in Georgia and South Carolina . S. riobravis applied at 6 109 infective juveniles (IJs) / acre provided up to 95 - 100% control of the root - knot , Meloidogyne sp ., sting , Belonolaimus longicaudatus, and ring nematode , Criconemella sp ., in Georgia , but S. carpocapsae had no effect . S. riobravis was as effective as the chemical nematicide , Fenamiphos (Nemacur 10G) at 4 weeks after treatment and more effective at 8 weeks after treatment . In South Carolina , both S. riobravis and S. carpocapsae applied at 1 109 IJs / acre provided up to 86 - 100 % control of the root - knot , sting and ring nematodes . Application of 6 109 IJs / acre increased control by only 4 - 14 % over the 1 109 dosage . Possible causes of differences in efficacy of S. carpocapsae at the two sites are discussed . It is concluded that S. riobravis may provide effective , predictable and economical control of PPNs in turfgrass . 相似文献
6.
Adventitious root formation in vitro in 1-mm stem slices cut from microshoots of apple cv. Jork 9 was studied using light
and electron microscopy. When indole-3-butyric acid (IBA) had been added to the medium, starch grains accumulated during the
first 24 h of culture in cells of the cambial region and in cells in the vicinity of vascular tissue and in the primary rays.
This accumulation occurred only in the basal part of explants. After that, the nuclei in these cells were activated, and the
density of the cytoplasm and the number of cell organelles increased, whereas starch was broken down. Cambium cells started
to divide transversely and at 96 h, after several divisions, a continuous ring of isodiametric cytoplasmic cells had appeared
around the xylem near the basal cutting surface. The cells in this ring were rich in cell structures, and did not contain
large starch grains and a central vacuole. Root meristemoids regenerated from the portions of the ring that were localized
in the primary rays. From the other cells in the ring, callus developed. The meristemoids did not grow into the direction
of the epidermis as in shoots, but along the vascular bundles. After emergence from the cutting surface, the meristemoids
were transformed into small, dome-like primordia. They developed a typical root apex with root cap, root ground meristem and
tracheid connection with shoot vascular tissue.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
7.
Angus Davison †§ Johnny D. S. Birks † Rachael C. Brookes † John E. Messenger† Huw I. Griffiths‡ 《Molecular ecology》2001,10(10):2479-2488
The flora and fauna of Europe are linked by a common biogeographic history, most recently the Pleistocene glaciations that restricted the range of most species to southern refugial populations. Changes in population size and migration, as well as selection, have all left a signature on the genetic differentiation. Thus, three paradigms of postglacial recolonization have been described, inferred from the patterns of DNA differentiation. Yet some species, especially wide-ranging carnivores, exhibit little population structuring between the proposed refugia, although relatively few have been studied due to the difficulty of obtaining samples. Therefore, we investigated mitochondrial variation in pine martens, Martes martes, in order to understand the extent to which they were affected by glacial cycles, and compared the results with an analysis of sequences from polecats, Mustela putorius. A general lack of ancient lineages, and a mismatch distribution that is consistent with an expanding population, is evidence that the present-day M. martes and Mu. putorius in central and northern Europe colonized from a single European refugium following a recent glaciation. There has also been interspecific mitochondrial introgression between M. martes and the sable M. zibellina in Fennoscandia. 相似文献
8.
The rate constant of modification of a specific thiol group, SH2, with N-ethylmaleimide (NEM) has been used to estimate the conformational change in the local area containing SH2 (SH2 region) of skeletal myosin as a structural probe. The rate of Mg2+-ATP-induced SH2 modification of subfragment-1 (S-l) isozymes was regulated by Ca2+ in the pCa range below 6.4 and was not regulated in the pCa range above 6.4. No substantial difference between S-1 containing alkali light chain, A1, (S-1(A1)) and S-1 containing alkali light chain, A2, (S-1(A2)) was observed in the Ca2+-dependent rate of SH2 modification. Due to the presence of this Ca2+ regulation in myosin (absence in S-1 isozymes) in the pCa range above 6.4, absence of 5,5-dithiobis-(2-nitrobenzoic acid) (DTNB) light chain in S-1 isozymes, and high affinity of Ca2+ for DTNB light chain, this Ca2+ regulation in the pCa range above 6.4 is possibly related to the Ca2+ binding to DTNB light chain. F-Actin, which is entirely free from tropomyosin and troponin, enhanced the rate of Mg2+-ATP-induced SH2 modification of S-1 isozymes equally and of myosin, and reduced the Ca2+ sensitivity with an increase in F-actin concentration. 相似文献
9.
The N-terminal -amino groups of 1-bungarotoxin (1-Bgt) fromBungarus multicinctus venom were modified with trinitrobenzene sulfonic acid and the modified derivative was separated by high performance liquid chromatography. The trinitrophenylated (TNP) derivative contained two TNP groups at the -amino groups of A chain and B chain and showed a marked decrease in enzymatic activity. Methionine residues at positions 6 and 8 of the A chain were oxidized with chloramine T or cleaved with cyanogen bromide to remove the N-terminal octapeptide. Oxidation of methionine residues and removal of the N-terminal octapeptide caused a precipitous decrease in enzymatic activity, whereas antigenicity remained unchanged. The presence of dihexanoyllecithin influenced the interaction between 1-Bgt and 8-antilinonaphthalene sulfonate (ANS) and revealed that 1-Bgt consists of two types of ANS-binding sites, one at the substrate binding site of the A chain and the other might be at the B chain. The modified derivatives still retained their affinity for Ca2+ and ANS, indicating that the N-terminal region is not involved in Ca2+ and substrate binding. A fluorescence study revealed that the -amino group of the A chain was in the vicinity of substrate binding site and that the TNP -amino groups were in proximity to Trp-19 of the A chain. In addition, the study showed that the N-terminal region is important for stabilizing the architectural environment of Trp-19. The results, together with the proposal that Trp-19 of the A chain is involved in substrate binding, suggest that the N-terminal region of the A chain plays a crucial role in maintaining a functional active site for 1-Bgt. 相似文献
10.
S. Živanović 《Human Evolution》1988,3(5):329-334
Studies of the morphological features of the temporal region of mesolithic skulls from Padina in the Iron Gate Gorge of the
Danube revealed a very prominent and large supramastoid ridge which is the most striking feature in skulls of both sexes.
Mastoid processes were larger in male skulls, but in 25% of the cases there was an overlap between the size of the processes
in male and female specimens. The mastoid ridge was prominent in both sexes. The digastric fossa was always well defined in
both sexes and in the two thirds of the skull specimens it was deep. The posterior root of the zygoma was prominent in all
the skulls, but it was better developed in the male specimens. The parietotemporal suture in both sexes rises above the level
of the pterion. There were no morphological or anthropometrical differences between the left and the right side of individual
skulls outside the limits of natural asymmetry. All these morphological characteristics of the temporal region may help in
racial and sexual diagnosis of the Mesolithic skulls from the Iron Gate Gorge. 相似文献