instruction:
In this task, you are given a passage which has a question and the context. You have to generate an answer to the question based on the information present in the context.
question:
Context: This study investigated whether deletion of the alpha1A-adrenoceptor gene influences contractile responses of mouse prostate to noradrenaline. Responses of mouse prostate to noradrenaline are known to be mediated by alpha1L-adrenoceptors, which are thought to be a functional phenotype of alpha1A-adrenoceptor.', 'Prostate tissues from alpha1A-adrenoceptor knockout mice which were homozygous (alpha1A -/-) and heterozygous (alpha1A +/-) for the disrupted alpha1A-adrenoceptor gene, as well as wild-type (alpha1A +/+) littermates were mounted in glass-isolated organ baths. Electrical field stimulation of nerves and exogenous application of noradrenaline were used to investigate the effects of alpha1A-adrenoceptor disruption on prostate contractility.', 'Frequency-response curves to electrical field stimulation (0.5 ms pulse duration, 60 V, 0.1-20 Hz) yielded frequency-dependent contractions. At frequencies of 10 and 20 Hz, prostates from alpha1A -/- mice elicited an approximately 30% decreased response compared with prostates from alpha(1A)+/+ mice. Prazosin (0.3 muM) attenuated responses to electrical field stimulation in prostates from alpha1A +/+ and alpha1A +/- mice but not from alpha1A -/- mice. Increasing concentrations of exogenously administered noradrenaline (10 nM-1 mM) produced mean concentration-response curves in prostates from alpha1A +/+ and alpha1A +/- mice, which were not different. Maximum responses to noradrenaline were decreased by approximately 80% in prostates from alpha1A -/- mice compared with alpha1A +/+ mice. Prazosin attenuated responses to noradrenaline in all genotypes.\Question: Is the alpha1A-adrenoceptor gene required for the alpha1L-adrenoceptor-mediated response in isolated preparations of the mouse prostate?
answer:
alpha1L-Adrenoceptor-mediated responses in mouse prostate are abolished in alpha1A -/- mice, demonstrating that the alpha1A-adrenoceptor gene is essential to the manifestation of the prostatic alpha1L-adrenoceptor phenotype. This implies that alpha1L-adrenoceptors are indeed a functional phenotype of alpha1A-adrenoceptor.

question:
Context: To determine the extent of genetic variation among internationally collected HIV-1 isolates, to analyse phylogenetic relationships and the geographic distribution of different variants.', 'Phylogenetic comparison of 70 HIV-1 isolates collected in 15 countries on four continents.', 'To sequence the complete gag genome of HIV-1 isolates, build multiple sequence alignments and construct phylogenetic trees using distance matrix methods and maximum parsimony algorithms.', 'Phylogenetic tree analysis identified seven distinct genotypes. The seven genotypes were evident by both distance matrix methods and maximum parsimony analysis, and were strongly supported by bootstrap resampling of the data. The intra-genotypic gag distances averaged 7%, whereas the inter-genotypic distances averaged 14%. The geographic distribution of variants was complex. Some genotypes have apparently migrated to several continents and many areas harbor a mixture of genotypes. Related variants may cluster in certain areas, particularly isolates from a single city collected over a short time.\Question: Does phylogenetic analysis of gag genes from 70 international HIV-1 isolates provide evidence for multiple genotypes?
answer:
The genetic variation among HIV-1 isolates is more extensive than previously appreciated. At least seven distinct HIV-1 genotypes can be identified. Diversification, migration and establishment of local, temporal 'blooms' of particular variants may all occur concomitantly.

question:
Context: The checkpoint kinase 1 (Chk1) functions not only in genotoxic stresses but also in normal cell cycle progression, particularly in the initiation, progression and fidelity of unperturbed mitosis. In this study, we investigated the role of Chk1 in regulating the metaphase-anaphase transition in mammalian cells.', 'The mitotic progression was monitored by flow cytometry analysis. The levels of cyclin B1, Cdc20 and Mad2 were measured by Western blotting. Metaphase chromosome alignment and the subcellular localization of Cdc20 and Mad2 were analyzed by immunofluorescence and confocal microscopy.', 'Cyclin B1 degradation and the metaphase-anaphase transition were severely blocked by Chk1 siRNA. Depletion of Chk1 induced chromosome alignment defect in metaphase cells. The kinetochore localization of Cdc20, Mad2 was disrupted in Chk1 depleted cells. Chk1 abrogation also dramatically reduced the protein expression levels of Cdc20 and Mad2.\Question: Is chk1 required for the metaphase-anaphase transition via regulating the expression and localization of Cdc20 and Mad2?
answer:
These results strongly suggest that Chk1 is required for the metaphase-anaphase transition via regulating the subcellular localization and the expression of Cdc20 and Mad2.