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341.
342.
The molecular organization of the beta-globin complex of the deer mouse, Peromyscus maniculatus 总被引:1,自引:0,他引:1
Padgett RW; Loeb DD; Snyder LR; Edgell MH; Hutchison CA d 《Molecular biology and evolution》1987,4(1):30-45
Recombinant DNA clones have been isolated that contain 80 kb of the
beta-globin complex from the deer mouse, Peromyscus maniculatus.
Comparisons of this complex with that from the laboratory mouse, Mus
domesticus (with an order 5'-Hbby, Hbb-bhO, Hbb-bhl, Hbb-bh2, Hbb-bh3,
Hbb-bl, Hbb-b2 3') highlight organizational trends in the beta-globin
complex since the two species diverged. Unlike other mammals studied thus
far, the deer mouse possesses three adult genes. Partial sequence analysis
indicates that each of the three adult genes is intact and hence may be
functional. Hybridization of one of the two Mus pseudogenes, Hbb-bh3, to
genomic blots from Peromyscus reveals that it has a homologous counterpart
in Peromyscus. Homologous genes to the two gamma-like Mus genes, Hbb-bhO
and Hbb-bhl, are also found in Peromyscus. The strong hybridization between
the Hbb-bhl genes and significant nucleotide similarity between the Hbb-bhO
genes suggest that both pairs are important for the ontogeny of these mice
although no known product has been identified for the Hbb-bhO genes. The
presence of Hbb-bhO and Hbb-bhl in Peromyscus suggests that the duplication
that created this related gene set occurred before the two lineages
diverged. A single gene for Hbb-y has been isolated from Peromyscus. The
adult region in Peromyscus has undergone significant divergence from the
same region in Mus, having three rather than two adult genes, the
acquisition of at least 15 kb of extra DNA relative to Mus, and possibly
the loss of the Hbb-bh2 pseudogene. The nonadult region of the complex, in
contrast, contains the same set of genes apparently distributed over the
same amount of DNA as in the Mus beta- globin complex. This observation
suggests that the embryonic region of the complex is more evolutionarily
stable than the adult region.
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343.
344.
A simple population dynamics model was constructed to simulate temporal
variability in the biomass of a dominant copepod Calanoides
carinatus (Copepoda: Calanoida) along the West Coast region of
South Africa. Calanoides carinatus is extensively
preyed upon by the commercially important anchovy Engraulis
capensis, thus variability in zooplankton production may serve
as a useful predictor of variability in anchovy recruitment levels. The
model developed here circumvents the need to include a large number of
parameters because it uses satellite-derived estimates of chlorophyll
a concentration and sea surface temperature as primary
inputs. Abundance estimates necessary to initialize the model are readily
obtainable from biannual research cruises. The model successfully simulates
observed features of a copepod population's response to pulses of upwelling
and is robust with respect to most of its parameters because minor changes
in their values result in predictable changes in model output. The model
showed greatest sensitivity to parameters that are difficult to determine
empirically, such as predator-induced mortality rates. Gaps in our present
understanding of the nature and scale of processes affecting copepod egg
abundance, survival and viability in the southern Benguela system were
identified as the dominant impediment to simulating copepod population
dynamics in the region.
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