Mouse chromosome 1

Chair of Committee for Mouse Chromosome 1     

SYSTEMATIC ANALYSIS OF SPHAEROPLEA (CHLOROPHYCEAE)1

A systematic investigation of the genus Sphaeroplea was conducted using cladistic analyses of both structural and isozyme characters for the same set of taxa. The structural data were not able to fully resolve some of the taxa while the isozyme data did produce a tree in which all nodes were supported by data. The structural characters were relatively consistent with one another, whereas the isozyme characters were much less internally consistent. Results from independent, cladistic analyses of both data sets support the concept that among those Sphaeroplea species investigated, S. fragilis Buchheim et Hoffman had an early divergence. The two data sets differed primarily in that the structural data support monophyly of the genus Sphaeroplea and the isozyme data do not. The greater relative consistency of the structural data suggests better support for trees inferred from its analysis. Furthermore, searches for character congruence between the two data sets revealed isozyme data which support monophyly of the genus Sphaeroplea, but had been overwhelmed by conflicting isozyme characters.     

Fast optimal genome tiling with applications to microarray design and homology search.

In this paper, we consider several variations of the following basic tiling problem: given a sequence of real numbers with two size-bound parameters, we want to find a set of tiles of maximum total weight such that each tiles satisfies the size bounds. A solution to this problem is important to a number of computational biology applications such as selecting genomic DNA fragments for PCR-based amplicon microarrays and performing homology searches with long sequence queries. Our goal is to design efficient algorithms with linear or near-linear time and space in the normal range of parameter values for these problems. For this purpose, we first discuss the solution to a basic online interval maximum problem via a sliding-window approach and show how to use this solution in a nontrivial manner for many of the tiling problems introduced. We also discuss NP-hardness results and approximation algorithms for generalizing our basic tiling problem to higher dimensions. Finally, computational results from applying our tiling algorithms to genomic sequences of five model eukaryotes are reported.     

THE TIME-COURSE OF PHOTOADAPTATION TO LOW-LIGHT IN PROROCENTRUM MARIAE-LEBOURIAE (DINOPHYCEAE)1

The estuarine dinoflagellate, Prorocentrum mariaelebouriae (Parke & Ballantine 1957) Faust 1974 undergoes increases in pigmentation and photosynthetic efficiency within several days of downward light shifts. These changes can be described by first-order kinetics, as has been reported previously for Chlorophyll (Chl) a in several phytoplankton species. The studies described in this paper were conducted with isolates of populations of Prorocentrum from the Chesapeake Bay. We determined rates of adaptation to low-light for cultures grown at a range of photon flux densities (I₀= 2.65–26.2 E.m^?2, d^?1, shifted to 6.3–7.0% I₀) at three temperatures (10°, 15°, and 20° C), bracketing the conditions this species experiences in situ. In this paper, I report the time-course of changes in α, P_max Chl a, peridinin, and I_k and first-order rate constants, K₁ for changes in α, Chl a and peridinin. cell^?1. K₁ for changes in α cell^?1 averaged 1.58 × 10^?2 h^?1 for conditions encompassing five light treatments and three temperatures; the corresponding mean for Chl a was 1.59 × 10^?2 h^?1. Increases in peridinin measured for five light treatments at 15° C showed a mean K₁ of 1.22 × 10^?2 h^?1, Average percent changes in per cell α, Chl a, and peridinin ranged from 0.4–4.0% h^?1 (10–90% d^?1) following exposure to low-light. Photoadaptive changes are important to Prorocentrum because in nature it occupies turbid waters (K_t≥ 0.5 m^?1) where the mixing depth often exceeds the depth of the photic layer. Cells are entrained beneath a seasonally-stable density discontinuity and are exposed to very low-light (< I E.m^?2.d^?1) for days to weeks during subpycnocline transport. The ability of this species to undergo changes in pigmentation and photosynthetic physiology confers increased efficiency of light harvesting and contributes to this species’survival in the estuary where it is an important component of the dinoflagellate flora.