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41.
Fruit developmental regulation of the kiwifruit actinidin promoter is conserved in transgenic petunia plants 总被引:5,自引:0,他引:5
We have examined the expression of actinidin, a cysteine protease found in kiwifruit, over the course of fruit development. Protease activity was first seen in fruit that had reached about half their final weight, and rose to high levels at harvest. The 5-flanking region (nucleotides –1301 to +58) of a kiwifruit actinidin gene was fused to the -glucuronidase (GUS)-coding region, and the chimaeric gene was introduced into transgenic petunia plants. Induction of the GUS gene was observed during the later stages of seed pod development, closely resembling the pattern of actinidin induction in fruit tissues of kiwifruit. Some GUS expression was also detected in the vascular system of the receptacle, leaves, stems and roots. A shorter promoter fragment consisting of nucleotides –115 to +58 conferred similar spatial and temporal regulation in some of the transgenic plants. 相似文献
42.
43.
Matthew J. Hansen Paolo Domenici Palina Bartashevich Alicia Burns Jens Krause 《Biological reviews of the Cambridge Philosophical Society》2023,98(5):1687-1711
Group-hunting is ubiquitous across animal taxa and has received considerable attention in the context of its functions. By contrast much less is known about the mechanisms by which grouping predators hunt their prey. This is primarily due to a lack of experimental manipulation alongside logistical difficulties quantifying the behaviour of multiple predators at high spatiotemporal resolution as they search, select, and capture wild prey. However, the use of new remote-sensing technologies and a broadening of the focal taxa beyond apex predators provides researchers with a great opportunity to discern accurately how multiple predators hunt together and not just whether doing so provides hunters with a per capita benefit. We incorporate many ideas from collective behaviour and locomotion throughout this review to make testable predictions for future researchers and pay particular attention to the role that computer simulation can play in a feedback loop with empirical data collection. Our review of the literature showed that the breadth of predator:prey size ratios among the taxa that can be considered to hunt as a group is very large (<100 to >102). We therefore synthesised the literature with respect to these predator:prey ratios and found that they promoted different hunting mechanisms. Additionally, these different hunting mechanisms are also related to particular stages of the hunt (search, selection, capture) and thus we structure our review in accordance with these two factors (stage of the hunt and predator:prey size ratio). We identify several novel group-hunting mechanisms which are largely untested, particularly under field conditions, and we also highlight a range of potential study organisms that are amenable to experimental testing of these mechanisms in connection with tracking technology. We believe that a combination of new hypotheses, study systems and methodological approaches should help push the field of group-hunting in new directions. 相似文献
44.
David L. Cheo Lisiane B. Meira Robert E. Hammer Dennis K. Burns Ana T.B. Doughty Errol C. Friedberg 《Current biology : CB》1996,6(12)
The significance of DNA repair to human health has been well documented by studies on xeroderma pigmentosum (XP) patients, who suffer a dramatically increased risk of cancer in sun-exposed areas of their skin [1] and [2]. This autosomal recessive disorder has been directly associated with a defect in nucleotide excision–repair (NER) [1] and [2]. Like human XP individuals, mice carrying homozygous mutations in XP genes manifest a predisposition to skin carcinogenesis following exposure to ultraviolet (UV) radiation [3], [4] and [5]. Recent studies have suggested that, in addition to roles in apoptosis [6] and cell-cycle checkpoint control [7] in response to DNA damage, p53 protein may modulate NER [8]. Mutations in the p53 gene have been observed in 50% of all human tumors [9] and have been implicated in both the early [10] and late [11] stages of skin cancer. To examine the consequences of a combined deficiency of the XPC and the p53 proteins in mice, we generated double-mutant animals. We document a spectrum of neural tube defects in XPC p53 mutant embryos. Additionally, we show that, following exposure to UV-B radiation, XPC p53 mutant mice have more severe solar keratosis and suffer accelerated skin cancer compared with XPC mutant mice that are wild-type with respect to p53. 相似文献
45.
We analysed the relative effects of food availability and temperature on rates of growth and development of a predatory planktonic
water mite, Piona exigua. Growth in length of mites fed Daphnia, Ceriodaphnia and Chydorus was analysed by Gompertz or von Bertalanffy curves; these curves were compared by parallel curve analysis.
Growth rates of nymphs and adult female mites increased with temperature; the duration of the imagochrysalis stage decreased.
Females grown at 10 °C were smaller at final size than females grown at 15 °C, 18 °C or 22 °C. Females reared at food levels
of 15 or 30 prey l−1 grew more slowly and were smaller than those provided with 60 or 120 prey l−1.
Nymphs grew more slowly when Daphnia were the only prey, than when smaller prey were available. Food level did not affect nymph growth at 10 °C or 15 °C, but
growth at 18 °C or 22 °C may have been slowed at the lowest food levels. Synergistic effects of temperature and food level
on nymph growth were apparent only from analysis of growth curves and not from stage duration data. 相似文献
46.
The role of colony-stimulating factors (CSFs) in regulating the synthesis of thrombospondin 1 (TSP1) by cultured human macrophages is investigated. Macrophage (M)-CSF is shown rapidly and transiently to induce two predominant species of TSP1 mRNA. One of these species was 3.2 kb in size and appeared to be specific to M-CSF-stimulated macrophages. Adherent M-CSF-treated macrophages are also shown to express abundant surface cell-associated TSP rapidly when examined by indirect immunofluorescence staining. Granulocyte-macrophage (GM)-CSF induced TSP1 mRNA at a later time point, and this was attributable to the effects of endogenous M-CSF induced by the GM-CSF; the GM-CSF-treated cells did not display surface-associated TSP after 3 hr of treatment. Analysis of the TSP1 protein synthesised by the M-CSF-treated macrophages revealed the expected trimeric form of the molecule. In addition, an unidentified 95-kDa protein was found to be covalently associated with immunoreactive TSP1, and this appeared to be specific to the macrophages as it was not found in TSP1 precipitated from other cell types. It is suggested that the induction of TSP1 by M-CSF may play an important role in the major physiological functions of macrophages. © 1995 Wiley-Liss, Inc. 相似文献
47.
Changes in key regulatory enzymes of hepatic carbohydrate metabolism after glucose loading of starved rats 总被引:5,自引:0,他引:5
T H Claus F Nyfeler H A Muenkel M G Burns T Pate S J Pilkis 《Biochemical and biophysical research communications》1984,125(2):655-661
When glucose was given to starved rats there was an increase in both 6-phosphofructo 2-kinase and pyruvate kinase activity and a decrease in fructose 2,6-bisphosphatase activity 30 min and 60 min later. These changes were accompanied by an increase in glycogen deposition and by modest, but significant increases in fructose 2,6-bisphosphate levels at the same time. Metabolite measurements indicated that flux through 6-phosphofructo 1-kinase and pyruvate kinase were increased. These results suggest that although glycogen deposition may occur via the gluconeogenic pathway, glycolysis is activated at the same time by changes in the phosphorylation state of key regulatory enzymes as well as by the small rise in fructose 2,6-bisphosphate. 相似文献
48.
Relationship of lipoamide dehydrogenases from Pseudomonas putida to other FAD-linked dehydrogenases 总被引:5,自引:0,他引:5
Pseudomonas putida produces two lipoamide dehydrogenases, LPD-glc and LPD-val. LPD-val is specifically required as the lipoamide dehydrogenase of branched-chain keto acid dehydrogenase and LPD-glc fulfills all other requirements for lipoamide dehydrogenase. Both proteins are dimers with one FAD per subunit. LPD-glc has an absorption maximum at 455 nm, but LPD-val has a maximum at 460 nm. Comparison of amino acid compositions revealed that LPD-glc was more closely related to Escherichia coli and pig heart lipoamide dehydrogenase than to LPD-val. LPD-val did not appear to be closely related to any of the proteins compared with the possible exception of mercuric reductase. 相似文献
49.
The chick brain microtubule-associated protein MAP2 can be phosphorylated in vitro to the extent of 12 mol/mol with GTP at the same sites as can be labelled by the cyclic AMP-independent protein kinase utilizing [gamma-32P]ATP as the phosphoryl donor. Consequently, the microtubule protein is chemically modified by the conditions usually employed for studies of microtubule assembly, so that the derived kinetic parameters may not relate to steady-state conditions. 相似文献
50.
S J Butler R B Payne I R Gunn J Burns C R Paterson 《BMJ (Clinical research ed.)》1984,289(6450):948-950
One quarter of 172 patients from two hospitals with no obvious disturbances of calcium homeostasis and with total serum calcium concentrations that were normal after adjustment for albumin concentration had low serum ionised calcium concentrations. The low values were not due to changes in pH but were associated with hypoalbuminaemia. Significant positive regressions of ionised calcium on albumin concentration were observed in patients from both hospitals and also in 48 healthy laboratory staff. Because the regressions did not differ between patients and healthy subjects the low ionised calcium values associated with hypoalbuminaemia are unlikely to have been of pathological importance. These findings indicate that interpreting serum ionised calcium concentrations in patients with a reduced serum albumin concentration on the basis of a reference range determined in subjects with a normal serum albumin concentration may be clinically misleading. 相似文献