Temperature influence on phytoplankton community growth rates

A large database of field estimates of phytoplankton community growth rates in natural populations was compiled and analyzed to determine the apparent temperature effect on phytoplankton community growth rate. We conducted an ordinary least squares regression to optimize the parameters in two commonly used growth-temperature relations (Arrhenius and Q10 models). Both equations fit the observational data equally with the optimized parameter values. The optimum apparent Q10 value was 1.47 ± 0.08 (95% confidence interval, CI). Microzooplankton grazing rates closely matched the temperature trends for phytoplankton growth. This likely reflects a dynamic adjustment of biomass and grazing rates by the microzooplankton to match their available food source, illustrating tight coupling of phytoplankton growth and microzooplankton grazing rates. The field-measured temperature effect and growth rates were compared with estimates from the satellite Carbon-based Productivity Model (CbPM) and three Earth System Models (ESMs), with model output extracted at the same month and sampling locations as the observations. The optimized, apparent Q10 value calculated for the CbPM was 1.51, with overestimation of growth rates. The apparent Q10 value in the Community Earth System Model (V1.0) was 1.65, with modest underestimation of growth rates. The GFDL-ESM2M and GFDL-ESM2G models produced apparent Q10 values of 1.52 and 1.39, respectively. Models with an apparent Q10 that is significantly greater than ~1.5 will overestimate the phytoplankton community growth response to the ongoing climate warming and will have spatial biases in estimated growth rates for the current era

Molecular Characterization of Shaker, a Drosophila Gene That Encodes a Potassium Channel

The Drosophila Shaker (Sh) gene appears to encode a type of voltage-sensitive potassium (K+) channel called the A channel. We have isolated Sh as part of a 350 kb chromosomal walk. The region around Sh contains four identified transcription units. We find that Sh corresponds to a very large transcription unit encompassing a total of about 95 kb of genomic DNA and split by a major 85 kb intron. Sh has multiple hydrophobic domains that have a high probability of being membrane-spanning, consistent with the proposal that it encodes an ion channel

Temperature influence on phytoplankton community growth rates

A large database of field estimates of phytoplankton community growth rates in natural populations was compiled and analyzed to determine the apparent temperature effect on phytoplankton community growth rate. We conducted an ordinary least squares regression to optimize the parameters in two commonly used growth-temperature relations (Arrhenius and Q10 models). Both equations fit the observational data equally with the optimized parameter values. The optimum apparent Q10 value was 1.47 ± 0.08 (95% confidence interval, CI). Microzooplankton grazing rates closely matched the temperature trends for phytoplankton growth. This likely reflects a dynamic adjustment of biomass and grazing rates by the microzooplankton to match their available food source, illustrating tight coupling of phytoplankton growth and microzooplankton grazing rates. The field-measured temperature effect and growth rates were compared with estimates from the satellite Carbon-based Productivity Model (CbPM) and three Earth System Models (ESMs), with model output extracted at the same month and sampling locations as the observations. The optimized, apparent Q10 value calculated for the CbPM was 1.51, with overestimation of growth rates. The apparent Q10 value in the Community Earth System Model (V1.0) was 1.65, with modest underestimation of growth rates. The GFDL-ESM2M and GFDL-ESM2G models produced apparent Q10 values of 1.52 and 1.39, respectively. Models with an apparent Q10 that is significantly greater than ~1.5 will overestimate the phytoplankton community growth response to the ongoing climate warming and will have spatial biases in estimated growth rates for the current era

Genetics and Molecular Biology of Ionic Channels in Drosophila

In this review we examine mutations that alter electrical excitability in the nervous system of the fruitfly, Drosophila melanogaster, and discuss how these mutations may be used to approach the molecular basis of ionic channel function

Identification of a Drosophila muscle development gene with structural homology to mammalian early growth response transcription factors.

In Drosophila, stripe (sr) gene function is required for normal muscle development. Some mutations disrupt embryonic muscle development and are lethal. Other mutations cause total loss of only a single muscle in the adult. Molecular analysis shows that sr encodes a predicted protein containing a zinc finger motif. This motif is homologous to the DNA binding domains encoded by members of the early growth response (egr) gene family. In mammals, expression of egr genes is induced by intercellular signals, and there is evidence for their role in many developmental events. The identification of sr as an egr gene and its pattern of expression suggest that it functions in muscle development via intercellular communication

A-type potassium channels expressed from Shaker locus cDNA.

A-type K+ currents are expressed in Xenopus oocytes injected with in vitro-synthesized transcripts from cDNAs for the Drosophila Shaker (Sh) locus. A single Sh gene product, possibly as a multimer, is sufficient for formation of functional A channels. Various Sh RNAs express A currents with distinct kinetic properties. An analysis of structure-function relationships shows that the conserved central region of Sh polypeptides determines ionic selectivity and overall channel behavior, whereas the divergent amino and carboxyl termini can modify channel kinetics. Alternative splicing of Sh gene transcripts may provide one mechanism for the generation of K+ channel diversity

A Pimarane Diterpene and Cytotoxic Angucyclines from a Marine-Derived Micromonospora sp. in Vietnam’s East Sea

A screening of our actinomycete fraction library against the NCI-60 SKOV3 human tumor cell line led to the isolation of isopimara-2-one-3-ol-8,15-diene (1), lagumycin B (2), dehydrorabelomycin (3), phenanthroviridone (4), and WS-5995 A (5). These secondary metabolites were produced by a Micromonospora sp. isolated from sediment collected off the Cát Bà peninsula in the East Sea of Vietnam. Compound 1 is a novel Δ8,9-pimarane diterpene, representing one of approximately 20 actinomycete-produced diterpenes reported to date, while compound 2 is an angucycline antibiotic that has yet to receive formal characterization. The structures of 1 and 2 were elucidated by combined NMR and MS analysis and the absolute configuration of 1 was assigned by analysis of NOESY NMR and CD spectroscopic data. Compounds 2–5 exhibited varying degrees of cytotoxicity against a panel of cancerous and non-cancerous cell lines. Overall, this study highlights our collaborative efforts to discover novel biologically active molecules from the large, underexplored, and biodiversity-rich waters of Vietnam’s East Sea