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151.
Summary Hamilton and Zuk (1982) proposed that the quality of male showy traits reflects genetically-based resistance to parasites and can be used by females to select mates that are less prone to parasitic attack. The hypothesis requires that a particular state of a variable showy trait should be associated with parasite infection. We tested this idea with a population of western fence lizards, Sceloporus occidentalis, infected with the malarial parasite, Plasmodium mexicanum. Ventral color pattern is strongly dimorphic in fence lizards and varies greatly among males in this population. Malaria-infected males exhibited significantly more black and less pale on their ventral surface than did noninfected males of similar body size. This difference was not a function of differing ages of infected and noninfected animals of the same body size. However, logistic regression demonstrated that females using male ventral color as a gauge of infection status would only marginally improve their chance of choosing a noninfected lizard over random selection of mates. 相似文献
152.
The qualitative distribution and quantitative estimates of nitrogenase (EC 1.7.99.2), glutamine synthetase (EC 6.3.1.2), phycoerythrin and ribulose 1,5-bisphosphate carboxylase/oxygenase (EC 4.1.1.39) were studied in the cyanobacterium Nostoc residing in internal cephalodia of the tripartite lichen Nephroma arcticum L. Polyclonal antisera, raised in rabbit against the proteins, and goat anti-rabbit IgG conjugated to 10 nm gold were used as probes to detect the antigens by transmission electron microscopy. Western blot analyses demonstrated the monospecificity of the antisera. Nitrogenase was localized in heterocysts, with vegetative cells showing a label intensity comparable to the background. Distribution of the antigen within the heterocysts was uniform. Glutamine synthetase labelling was very low, but appeared to be distributed in both cell types. An intense phycoerythrin labelling was associated with the thylakoid region of the vegetative cells, whereas a much lower labelling was observed in the heterocyst. No significant differences were found between cyanobionts in younger and older cephalodia except for the nitrogenase labelling, which was higher in heterocysts of the cyanobiont in younger cephalodia. Most of the ribulose 1,5-bisphosphate carboxylase/oxygenase (Rubisco) label was present in vegetative cells. The Rubisco label was pronounced in the carboxysomes, whereas the label in the cytoplasm, on a unit area basis, was much lower. Heterocysts showed a label intensity similar to that of the vegetative cell cytoplasm. In Nostoc of the bipartite lichen Peltigera canina L., the Rubisco protein showed a comparable distribution pattern, but the average number of carboxysomes per vegetative cell was about 4 times higher. 相似文献
153.
154.
Tomato (Lycopersicon esculentum Mill. cv. Moneymaker) plants have been wounded to induce the accumulation of proteinase-inhibitor proteins (PI proteins) at the local site of injury and systemically in unwounded tissues. To determine the range of genes affected in the wound-response, polysomal mRNA has been isolated from the damaged leaves and from systemically responding leaves over a time-course of 2, 4, 10 and 24 h after wounding. Changes in the pattern of 35S-translation products indicate that the events that occur at the local wound-site are different from those that occur systemically, both with respect to the number of genes that are regulated and the timing of their regulation. In order to compare the effects of wounding and an endogenous systemic signal generated at the wound-site with those of elicitor (proteinase-inhibitor-inducing factor, PIIF) treatment of excised plants, polysomal mRNA has also been isolated from leaves of plants over a time-course of 2, 4, 10 and 24 h after PIIF-treatment. Changes in the pattern of 35S-translation products indicates that the events induced by PIIF resemble those induced by mechanical injury, rather than those induced by the endogenous systemic signal.Abbreviations IFF
isoelectric focussing
- PI proteins
proteinase inhibitor proteins
- PIIF
proteinase-inhibitor-inducing factor
- ssRubisco
small subunit of ribulose-1,5-bisphosphate carboxylase 相似文献
155.
Substrate specifity of the proton-driven hexose cotransport carrier in the plasmalemma of photoautotrophic suspension cells of Chenopodium rubrum L. has been studies through the short-term perturbation of 14C-labelled efflux of 3-O-methyl-d-glucose. Efflux, occurring exclusively via carrier-mediated exchange diffusion, is trans-stimulated by the substrate and trans-inhibited by the glucose-transport inhibitors phlorizin (K 1/2=7.9 mM) and its aglucon phloretin (K 1/2=84 μM); with both inhibitors, 3-O-methyl-d-glucose efflux may be blocked completely. Trans-stimulation of efflux (up to fourfold) by a variety of the d-enantiomers of neutral hexoses, including glucose (K 1/2=48 μM), 3-O-methyl-d-glucose (K 1/2=139 μM), and fructose (K 1/2=730 μM), but not by, for instance, d-allose, and l-sorbose, shows that carrier-substrate interaction critically involves the axial position at C-1 and C-3, respectively. We suggest that substrate binding by the Chenopodium hexose carrier involves both hydrophobic interaction with the pyran-ring and hydrogen-ion bonding at C-1 and C-3 of the d-glucose conformation. 相似文献
156.
When young wheat (Triticum aestivum L.) or barley (Hordeum vulgare L.) plants were deprived of an external sulphate supply (-S plants), the capacity of their roots to absorb sulphate, but not phosphate or potassium, increased rapidly (derepression) so that after 3–5 d it was more than tenfold that of sulphate-sufficient plants (+S plants). This increased capacity was lost rapidly (repression) over a 24-h period when the sulphate supply was restored. There was little effect on the uptake of L-methionine during de-repression of the sulphate-transport system, but S input from methionine during a 24-h pretreatment repressed sulphate influx in both+S and-S plants.Sulphate influx of both+S and-S plants was inhibited by pretreating roots for 1 h with 4,4-diisothiocyanatostilbene-2,2-disulphonic acid (DIDS) at concentrations > 0.1 mol · m-3. This inhibition was substantially reversed by washing for 1 h in DIDS-free medium before measuring influx. Longer-term pretreatment of roots with 0.1 mol·m-3 DIDS delayed de-repression of the sulphatetransport system in-S plants but had no influence on+S plants in 3 d.The sulphydryl-binding reagent, n-ethylmaleimide, was a very potent inhibitor of sulphate influx in-S roots, but was much less inhibitory in +S roots. Its effects were essentially irreversible and were proportionately the same at all sulphate concentrations within the range of operation of the high-affinity sulphate-transport system. Inhibition of influx was 85–96% by 300 s pretreatment by 0.3 mol·m-3
n-ethylmaleimide. No protection of the transport system could be observed by including up to 50 mol·m-3 sulphate in the n-ethylmaleimide pre-treatment solution. A similar differential sensitivity of-S and+S plants was seen with p-chloromercuriphenyl sulphonic acid.The arginyl-binding reagent, phenylglyoxal, supplied to roots at 0.25 or 1 mol·m-3 strongly inhibited influx in-S wheat plants (by up to 95%) but reduced influx by only one-half in+S plants. The inhibition of sulphate influx in-S plants was much greater than that of phosphate influx and could not be prevented by relatively high (100 mol·m-3 sulphate concentrations accompanying phenylglyoxal treatment. Effects of phenylglyoxal pretreatment were unchanged for at least 30 min after its removal from the solution but thereafter the capacity for sulphate influx was restored. The amount of new carrier appearing in-S roots was far greater than in+S roots over a 24-h period.The results indicate that, in the de-repressed state, the sulphate transporter is more sensitive to reagents binding sulphydryl and arginyl residues. This suggests a number of strategies for identifying the proteins involved in sulphate transport.Abbreviations DIDS
4,4-diisothiocyanatostilbene-2,2-disulphonic acid
- NEM
n-ethylmaleimide
- PCMBS
p-chloromercuriphenyl sulphonic acid 相似文献
157.
Nitrate reduction in roots and shoots and exchange of reduced N between organs were quantitatively estimated in intact 13-d-old seedlings of two-row barley (Hordeum vulgare L. cv. Daisengold) using the 15N-incorporation model (A. Gojon et al. (1986) Plant Physiol. 82, 254–260), except that NH
+
4
was replaced by NO
-
2
. N-depleted seedlings were exposed to media containing both nitrate (1.8 mM) and nitrite (0.2 mM) under a light-dark cycle of 12:12 h at 20°C; the media contained different amounts of 15N labeling. Experiments were started either immediately after the beginning (expt. 1) or immediately prior to the end (expt. 2) of the light period, and plants were sampled subsequently at each light-dark transition throughout 36 h. The plants effectively utilized 15NO
-
3
and accumulated it as reduced 15N, predominantly in the shoots. Accumulation of reduced 15N in both experiments was nearly the same at the end of the experiment but the accumulation pattern in roots and shoots during each 12-h period differed greatly depending on time and the light conditions. In expt. 1, the roots accounted for 31% (light), 58% (dark), and 9% (light) of nitrate reduction by the whole plants, while in expt. 2 the contributions of the root were 82% (dark), 20% (light), and 29% (dark), during each of the three 12-h periods. Xylem transport of nitrate drastically decreased in the dark, but that of reduced N rather increased. The downward translocation of reduced 15N increased while nitrate reduction in the root decreased, whereas upward translocation decreased while nitrate reduction in the shoot increased. We conclude that the cycling of reduced N through the plant is important for N feeding of each organ, and that the transport system of reduced N by way of xylem and phloem, as well as nitrate reduction by root and shoot, can be modulated in response to the relative magnitude of reduced-N demands by the root and shoot, with the one or the other predominating under different circumstances.Symbols Anl
accumulation of reduced 15N from 15NO
-
3
in 14NO
-
3
-fed roots of divided root system
- Ar
accumulation in root of reduced 15N from 15NO
-
3
- As
accumulation in shoot of reduced 15N from 15NO
-
3
- Rr
15NO
-
3
reduction in root
- Rs
15NO
-
3
reduction in shoot
- Tp
translocation to root of shoot-reduced 15N from 15NO
-
3
in phloem
- Tx
translocation to shoot of root-reduced 15N from 15NO
-
3
in xylem 相似文献
158.
Diurnal oscillations of steady-state mRNA levels encoding the chlorophyll a/b-binding proteins were monitored inLycopersicon esculentum, Glycine max, Phaseolus vulgaris, P. aureus, P. coccineus, Pisum sativum, Sinapis alba, Hordeum vulgare,
Triticum aestivum andZea mays. In these plant speciescab mRNA accumulation increases and decreases periodically indicating i) that the expression of the genes for chlorophyll a/b-binding
proteins (cab genes) is controlled by a circadian rhythm, and ii) that the rhythm is widely distributed among monocotyledonous and dicotyledonous
plant species. A detailed characterization of the pattern ofcab mRNA expression in tomato leaves shows that the amplitude of the oscillation is dependent on i) the developmental stage of
the leaves, ii) the circadian phase and duration of light and iii) the circadian phase and duration of darkness. In addition
to the chlorophyll a/b-binding proteins, genes coding for other cellular functions were examined for cyclic variations of
their mRNA levels. The analysis includes genes involved in i) carbon metabolism (e.g. phosphoenolpyruvate carboxylase, pyruvate
orthophosphate dikinase, alpha amylase, fructose-1,6-bisphosphate aldolase, triosephosphate isomerase), ii) photosynthesis
(large and small subunit of ribulose-1,5-bisphosphate carboxylase/oxygenase, QB-binding protein, reaction-center protein of photosystem I) and iii) other physiological or morphological reactions (e.g.
ubiquitin, actin). However, no periodic fluctuation pattern was detected for the mRNA levels of these genes in tomato and
maize leaves. 相似文献
159.
A few reports have suggested the possibility that feeding conditions might affect the sexual maturation of free-ranging Japanese
monkeys in provisionized troops. In the present study, the sexual maturation of male monkeys at Takasakiyama in 1984, nine
years after the start of restriction of artificial feeding, was examined externally and histologically and the results were
compared with data obtained in 1971, when artificial foods were abundantly given. Spermatogenesis was not observed in any
of the males under 4.5 years old in the present study, whereas it was noted in some premature 3.5-year-old males and in all
males over 4.5 years old in the 1971 study. The age of sexual maturation thus rose by one or more years over the 13-year period
from 1971 to 1984. The lag in sexual maturation of the males at Takasakiyama in 1984 could have been induced by the restriction
of artificial feeding. 相似文献
160.
V. I. Yermolaev G. I. Karasik T. M. Khlebodarova N. M. Matveeva M. R. Mullakandov A. M. Nayakschin T. V. Shumny N. B. Rubtsov O. L. Serov O. K. Baranov 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1989,78(1):93-96
Summary Using cloned cDNA for human 2-macroglobulin (A2M) as a probe, mink-Chinese hamster hybrid cells were analysed. The results allowed us to assign a gene for A2M to mink chromosome 9. Breeding tests demonstrated that the Lpm-locus coding for other related -macroglobulin protein and the gene for peptidase B (PEPB) are linked 11±3 cm apart. The PEPB gene is located on mink chromosome 9, and hence, the Lpw-locus is on the same mink chromosome. The relationship of the genetic systems controlling the isotypically different -macroglobulins in mink serum are discussed. 相似文献