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61.
Frank-Michael Stolz Hans-Peter Pfau Gernot Reipen Susanne Schnittger Karl-Heinz Grzeschik Ingo Hansmann 《Genomics》1991,11(4):948-955
Employing the flow-sorted chromosome 20-specific DNA library LL20NS01, we isolated seven novel unique poly- and monomorphic DNA markers specific to human chromosome 20. Initially, 201 phage clones were analyzed regarding insert size and repetitivity. By testing 14 single- and low-copy number clones for their ability to detect RFLPs, three polymorphisms were revealed by two probes, pFMS22-1.4 [D20S22] and pFMS76 [D20S23]. Seven of twenty probes (35%) were assigned to chromosome 20 using a somatic cell hybrid DNA panel. Five of them were regionally mapped by in situ hybridization. Three DNA markers, pFMS51 [D20S29], pFMS76 [D20S23], and pFMS106 [D20S30], were assigned to 20p11.2-p12, and two markers, pFMS22-1.4 [D20S22] and pFMS135 [D20S31], to 20q12-q13.3. Our new chromosome 20-specific DNA markers should be useful for the molecular characterization of this rather underpopulated human chromosome. 相似文献
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Abstract: [3 H]Strychnine specifically binds to membrane fractions isolated from rat retinae. The binding is saturable, with an apparent dissociation constant, K D , of 14.3 × 10−9 M and 205 fmol bound/mg protein. Specific binding is time-dependent and proportional to protein concentration. Glycine and taurine are equally potent inhibitors of [3 H]strychnine binding ( K i = 4 × 10−5 M); no other amino acids endogenously present in the retina inhibited [3 H]strychnine binding. 相似文献
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Adenosine and guanosine uptake have been studied in the rat retina. Both nucleosides are taken up in a time- and temperature-dependent manner by dispersed rat retinal cells. The uptake of both nucleosides is Na+-dependent and Ca++-independent. Initial rate studies of guanosine and adenosine uptake demonstrate a single uptake process for each nucleoside with KD values of 2.1 and 2.9 uM, and maximal rates of 24 and 17 pmol/mg protein/min, respectively. Guanosine uptake was inhibited by adenosine with a KI of 12.1 uM whereas guanosine inhibited adenosine uptake with a KI value greater than 10?3 M. LN6-phenylisopropyladenosine, a nucleoside analog, was the most potent inhibitor of adenosine and guanosine uptake with KI values of 25 and 8 uM, respectively. Phosphodiesterase inhibitors (isobutylmethylxanthine and theophylline) and biogenic amines (dopamine, norepinephrine, and histamine) had no significant effect on the uptake of guanosine or adenosine at concentrations up to 100 uM. 相似文献
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"Generalized distances" between centromeres were statistically analyzed (chi2 test) on 50 normal female trypsin-banded metaphase figures. This study revealed that the homologous chromosomes of the pairs 13, 17, 14, and 21 lie closer together than would be expected by a reference distribution, and this in a statistically significant way. The same relative position was demonstrated for the chromosome groups 13-14, 13-21, 14-21, 15-22, and 14-22. Evidences were collected that also showed that homologous chromosomes of the pairs 1, 19, and 20 and the chromosome groups 15-21, 13-15, and 18-20 tend to lie closer together. Giving a functional interpretation to the phenomenon of non-random distribution of chromosomes in metaphase figures, it may be suggested that the chromosomes 13, 14, and 21 are involved in the organization of the human nucleolar organizers, more frequently than the other D- and G-group chromosomes. 相似文献
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Evelien Jongepier Susanne Foitzik 《Proceedings. Biological sciences / The Royal Society》2016,283(1822)
Division of labour is of fundamental importance for the success of societies, yet little is known about how individual specialization affects the fitness of the group as a whole. While specialized workers may be more efficient in the tasks they perform than generalists, they may also lack the flexibility to respond to rapid shifts in task needs. Such rigidity could impose fitness costs when societies face dynamic and unpredictable events, such as an attack by socially parasitic slavemakers. Here, we experimentally assess the colony-level fitness consequences of behavioural specialization in Temnothorax longispinosus ants that are attacked by the slavemaker ant T. americanus. We manipulated the social organization of 102 T. longispinosus colonies, based on the behavioural responses of all 3842 workers. We find that strict specialization is disadvantageous for a colony''s annual reproduction and growth during slave raids. These fitness costs may favour generalist strategies in dynamic environments, as we also demonstrate that societies exposed to slavemakers in the field show a lower degree of specialization than those originating from slavemaker-free populations. Our findings provide an explanation for the ubiquity of generalists and highlight their importance for the flexibility and functional robustness of entire societies. 相似文献