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Comparative phylogeography of two co‐distributed but ecologically distinct rainbowfishes of far‐northern Australia 下载免费PDF全文
Andrew T. Mather Jeffrey O. Hanson Lisa C. Pope Cynthia Riginos 《Journal of Biogeography》2018,45(1):127-141
Aim
To test the influence of historical and contemporary environment in shaping the genetic diversity of freshwater fauna we contrast genetic structure in two co‐distributed, but ecologically distinct, rainbowfish; a habitat generalist (Melanotaenia splendida) and a habitat specialist (M. trifasciata).Location
Fishes were sampled from far northern Australia (Queensland and Northern Territory).Methods
We used sequence data from one mitochondrial gene and one nuclear gene to investigate patterns of genetic diversity in M. splendida and M. trifasciata to determine how differences in habitat preference and historical changes in drainage boundaries affected patterns of connectivity.Results
Melanotaenia splendida showed high levels of genetic diversity and little population structure across its range. In contrast, M. trifasciata showed high levels of population structure. Whereas phylogeographic patterns differed, both species showed a strong relationship between geographical distance and genetic differentiation between populations. Melanotaenia splendida showed a shallower relationship with geographical distance, and genetic differentiation was best explained by stream length and a lower scaled ocean distance (11.98 times coast length). For M. trifasciata, genetic differentiation was best explained by overwater distance between catchments and ocean distance scaled at 1.16 × 106 times coast length.Main conclusions
Connectivity of freshwater populations inhabiting regions periodically interconnected during glacial periods appears to have been affected by ecological differences between species. Species‐specific differences are epitomized here by the contrast between co‐distributed congeners with different habitat requirements: for the habitat generalist, M. splendida, there was evidence for greater historical genetic connectivity with oceans as a weaker barrier to gene exchange in contrast with the habitat specialist, M. trifasciata. 相似文献3.
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The effect of concanavalin A on the rat electro-olfactogram. Differential inhibition of odorant response. 总被引:1,自引:1,他引:0 下载免费PDF全文
When the rat olfactory mucosa is treated with concanavalin A, it subsequently shows diminished sensitivity towards 60% of the 112 odorants tested (as judged by the amplitude of the electro-olfactogram response). Odorants containing four to six carbon atoms tend to show the largest (absolute) diminutions, suggesting a receptor for this kind of odorant, although the structural specificity is weak. The receptor seems to be of particular importance in the detection of thiols, carboxylic acids and hydrocarbons of the above size, since these compounds loose the highest proportion of their original signal. The concanavalin A appears to be binding to the glycan of one or more cell-surface proteins. The binding may be at, or close to, at least one odorant receptor. 相似文献
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Gareth Williams Jaswinder S Gill Vic Aber Hugh M Mather 《BMJ (Clinical research ed.)》1988,296(6617):233-235
Vibration perception threshold was measured with a biothesiometer by a single observer at both medial malleoli and both big toes in 110 diabetic patients aged 15-65 selected at random and in 64 non-diabetic subjects aged 20-65. The vibration perception threshold showed appreciable individual variation both between contralateral sites and between ipsilateral sites, differing by at least 30% between the big toes in 26 (24%) of the diabetic patients and 16 (25%) of the non-diabetic group. Variability between sites was significantly greater in the diabetics than the normal subjects. The vibration perception threshold exceeded published normal values at one or more sites in 22 of the diabetic patients but at all four sites in only four.The wide variability in vibration perception threshold among sites may be due to the tissue characteristics locally and, in diabetic patients, possibly to asymmetric neuropathy. Biothesiometer readings at single or unilateral sites may be unrepresentative or misleading. 相似文献
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In many regions of Iran, crops are irrigated with municipal and industrial wastewater that contain a variety of metals. The purpose of this study was to simulate the level of metals that may be presented to plants over a growing season in a controlled laboratory setting. Cadmium, lead, arsenic, chromium, mercury, nickel, copper, zinc, and selenium were applied to plants at the high rate of 200 g metal/ha/wk. The following plants were examined for metal accumulation and effects on yield: garden cress (Lipidium sativum), leek (Allium porrum L.), basil (Ocimum basilicum L.), mint (Mentha arvensis L.), onion (Allium capa L.), radish (Raphanus sativus L.), and tarragon (Artemisia draculus L.). All plants showed significant uptake of all metals when compared to control (p=0.05), and growth was significantly reduced (p=0.05). Cadmium and chromium levels of 85±7.4 and 47.6±8.9 μg/g); selenium levels were highest in tarragon (16.5±5.8 μg/g). Zinc levels were similar (p=0.05) in all species tested, as were mercury and lead. The remaining metals (nickel and copper) showed significant differences in uptake, depending on plant species. 相似文献
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Seven mutants of Chlorella pyrenoidosa (Emerson strain 3) impaired for sulfate utilization have been isolated after treatment of the wild-type organism with nitrosoguanidine by replica plating on media containing thiosulfate and l-methionine. These mutants fall into three classes based on their ability to grow on sulfate, accumulate compounds labeled from sulfate-35S, and reduce adenosine 3′-phosphate 5′-phosphosulfate-35S (PAPS-35S) to thiosulfate-35S. Mutant Sat2− cannot grow on sulfate, but it accumulates thiosulfate-35S and homocysteic acid-35S from sulfate-35S in vivo. In addition, extracts of mutant Sat2− reduce PAPS-35S to thiosulfate-35S, indicating the possession of enzyme fractions S and A, both of which are required for thiosulfate formation. Mutants Sat1−, Sat3−, Sat4−, Sat5−, and Sat6− cannot grow on sulfate, and their extracts lack the ability to reduce PAPS-35S to thiosulfate-35S. Mutant Sat7−R1, a probable revertant, can grow on sulfate but still lacks the ability to reduce PAPS-35S to thiosulfate-35S in vitro. Complementation experiments in vitro show that the block in formation of acid-volatile radioactivity in every case is due to the absence of activity associated with fraction S. All mutants can grow on thiosulfate and all possess the activating enzymes which convert sulfate to PAPS. Through a comparison of nutritional and enzymatic characteristics, the first outlines of a branched and complicated pathway for sulfate reduction in Chlorella are beginning to emerge. 相似文献
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