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Understanding the dynamics of bodies of water and their impact on the global
environment requires sensing information over the full volume of water. In this article,
we develop a gradient-based decentralized controller that dynamically adjusts the depth
of a network of underwater sensors to optimize sensing for computing maximally detailed
volumetric models. We prove that the controller converges to a local minimum and show
how the controller can be extended to work with hybrid robot and sensor network systems.
We implement the controller on an underwater sensor network with depth adjustment
capabilities. Through simulations and in-situ experiments, we verify the functionality and
performance of the system and algorithm.

Cancer cells grown in 3D spheroid cultures are considered more predictive for clinical
efficacy. The marine natural product dragmacidin D induces apoptosis in MDA-MB-231 and MDAMB-
468 triple-negative breast cancer (TNBC) spheroids within 24 h of treatment while showing no
cytotoxicity against the same cells grown in monolayers and treated for 72 h. The IC50 for cytotoxicity
based on caspase 3/7 cleavage in the spheroid assay was 8 ± 1 µM in MDA-MB-231 cells and
16± 0.6 µM in MDA-MB-468 cells at 24 h. No cytotoxicity was seen at all in 2D, even at the highest
concentration tested. Thus, the IC50 for cytotoxicity in the MTT assay (2D) in these cells was found to
be >75 µM at 72 h. Dragmacidin D exhibited synergy when used in conjunction with paclitaxel, a
current treatment for TNBC. Studies into the signaling changes using a reverse-phase protein array
showed that treatment with dragmacidin D caused significant decreases in histones. Differential
protein expression was used to hypothesize that its potential mechanism of action involves acting
as a protein synthesis inhibitor or a ribonucleotide reductase inhibitor. Further testing is necessary
to validate this hypothesis. Dragmacidin D also caused a slight decrease in an invasion assay in
the MDA-MB-231 cells, although this failed to be statistically significant. Dragmacidin D shows
intriguing selectivity for spheroids and has the potential to be a treatment option for triple-negative
breast cancer, which merits further research into understanding this activity.

The Indian River Lagoon (IRL), a 156-mile-long estuary located on the eastern coast of
Florida, experiences phytoplankton bloom events due to increased seasonal temperatures coupled
with anthropogenic impacts. This study aimed to gather data on the toxicity to human cells and
to identify secondary metabolites found in water samples collected in the IRL. Water samples
from 20 sites of the IRL were collected during the wet and dry seasons over a three-year period.
A panel of cell lines was used to test cytotoxicity. Hemagglutination, hemolysis, and inhibition
of protein phosphatase 2A (PP2A) were also measured. Cytotoxic blooms were seen both in the
south (Microcystis) and the north (Pyrodinium) of the IRL. Each toxin induced a consistent pattern
of cytotoxicity in the panel of human cell lines assayed. During blooms, cytotoxicity due to a
single type of toxin is obvious from this pattern. In the absence of blooms, the cytotoxicity seen
reflected either a mixture of toxins or it was caused by an unidentified toxin. These observations
suggest that other toxins with the potential to be harmful to human health may be present in the
IRL. Moreover, the presence of toxins in the IRL is not always associated with blooms of known
toxin-producing organisms.

Includes a copy of this story published in The Sunday Review.

Includes correspondence from Fawcett Publications, Inc.