Estimating analytical variability in two-dimensional data

Throughout the course of drug development there are many instances in which a variability assessment within a set of analytical data is required, which may be challenging for techniques that produce two-dimensional data. This note describes an interval-based approach to variability assessment and demonstrates its applicability for analysis of near-UV circular dichroism (CD) spectra. The approach is generalizable and could be applied to two-dimensional data from other analytical techniques as well.     

Toxic benthic freshwater cyanobacterial proliferations: Challenges and solutions for enhancing knowledge and improving monitoring and mitigation

1. This review summarises knowledge on the ecology, toxin production, and impacts of toxic freshwater benthic cyanobacterial proliferations. It documents monitoring, management, and sampling strategies, and explores mitigation options.
2. Toxic proliferations of freshwater benthic cyanobacteria (taxa that grow attached to substrates) occur in streams, rivers, lakes, and thermal and meltwater ponds, and have been reported in 19 countries. Anatoxin- and microcystin-containing mats are most commonly reported (eight and 10 countries, respectively).
3. Studies exploring factors that promote toxic benthic cyanobacterial proliferations are limited to a few species and habitats. There is a hierarchy of importance in environmental and biological factors that regulate proliferations with variables such as flow (rivers), fine sediment deposition, nutrients, associated microbes, and grazing identified as key drivers. Regulating factors differ among colonisation, expansion, and dispersal phases.
4. New -omics-based approaches are providing novel insights into the physiological attributes of benthic cyanobacteria and the role of associated microorganisms in facilitating their proliferation.
5. Proliferations are commonly comprised of both toxic and non-toxic strains, and the relative proportion of these is the key factor contributing to the overall toxin content of each mat.
6. While these events are becoming more commonly reported globally, we currently lack standardised approaches to detect, monitor, and manage this emerging health issue. To solve these critical gaps, global collaborations are needed to facilitate the rapid transfer of knowledge and promote the development of standardised techniques that can be applied to diverse habitats and species, and ultimately lead to improved management.

     

The effect of anti-foam agents on the ultrafiltration of a protease solution

Polydimethylsiloxane and polypropylene glycol-based anti-foam agents adversely influence the ultrafiltration rate of a protease solution with polysulfon membranes. Four propietary agents have been compared, of which Rhodosil 426 R (ex Rhone Poulenc, France), an emulsion of polydimethylsiloxane, proved to have the least influence. With this agent, the relative filtration flux of a protease solution decreased by a factor of two for concentrations of anti-foam agent higher than 0.25 cm³/dm³. A simple, quasisteady-state model developed on the basis of data obtained from total recycle experiments with this anti-foam agent, well predicted the temporal variation of protease concentration during batch ultrafiltration experiments with and without Rhodosil 426 R.List of Symbols A _uf m² total membrane area - C _af dm³/m³ concentration of anti-foam agent - C _af,0 dm³/m³ initial concentration of anti-foam agent in the feed solution - C _e kg/m³ protease powder concentration - C _e,0 kg/m³ initial protease powder concentration in the feed solution - J m³/s ultrafiltration rate - J _w m³/m²s water flow for a clean membrane under processing conditions - R _af rejection coefficient for anti-foam agent - R _e rejection coefficient for protein - RF % relative filtration rate - t s filtration time - V m³ concentrate volume - V ₀ m³ volume to be concentrated - V _t m³ end volume     

STORAGE AND GERMINATION OF CHARA OOSPORES

Germination tests were conducted on 39 collections of Chara oospores stored under 4 different conditions for periods of approximately 4 yr. In general, storage of dried oospores at low temperatures (3 C) provided the most satisfactory means for long-term preservation of viable disseminules. Oospore germination zuas higher in light than in darkness. Effects of temperature and substrate upon germination were explored briefly.     

Oceanographic features and limited dispersal shape the population genetic structure of the vase sponge Ircinia campana in the Greater Caribbean

Understanding population genetic structure can help us to infer dispersal patterns, predict population resilience and design effective management strategies. For sessile species with limited dispersal, this is especially pertinent because genetic diversity and connectivity are key aspects of their resilience to environmental stressors. Here, we describe the population structure of Ircinia campana, a common Caribbean sponge subject to mass mortalities and disease. Microsatellites were used to genotype 440 individuals from 19 sites throughout the Greater Caribbean. We found strong genetic structure across the region, and significant isolation by distance across the Lesser Antilles, highlighting the influence of limited larval dispersal. We also observed spatial genetic structure patterns congruent with oceanography. This includes evidence of connectivity between sponges in the Florida Keys and the southeast coast of the United States (>700 km away) where the oceanographic environment is dominated by the strong Florida Current. Conversely, the population in southern Belize was strongly differentiated from all other sites, consistent with the presence of dispersal-limiting oceanographic features, including the Gulf of Honduras gyre. At smaller spatial scales (<100 km), sites showed heterogeneous patterns of low-level but significant genetic differentiation (chaotic genetic patchiness), indicative of temporal variability in recruitment or local selective pressures. Genetic diversity was similar across sites, but there was evidence of a genetic bottleneck at one site in Florida where past mass mortalities have occurred. These findings underscore the relationship between regional oceanography and weak larval dispersal in explaining population genetic patterns, and could inform conservation management of the species.Subject terms: Genetic variation, Ecology