Bioactivity and molecular modelling of diphenylsulfides and diphenylselenides

Bis(2-bromo-4,5-dimethoxyphenyl)sulfide (5) and bis(2-bromo-4,5-dimethoxyphenyl) selenide (7) have been shown to block cells in the G2/M phase of the cell cycle, whereas the debromo (4, 6) equivalents do not. The dibromoselenide (7) is cytotoxic to tumour cells in vitro and has been shown to increase the mitotic index of treated cells. These biological effects are consistent with disruption of the mitotic apparatus. This agent does not inhibit microtubule assembly in vitro, but does bind to tubulin. Molecular modelling of these structures indicates that their spatial and electronic structures may make an important contribution to the biological activity.     

The legacy of forest logging on organic matter inputs and storage in tropical streams

Riparian forests play an important role in stream ecosystems, as they support biodiversity, reduce water erosion, and provide litter that fuels aquatic biota. However, they are affected by great array of anthropogenic threats (e.g., fire, logging, and organic pollution), which alter species composition and their physical structure. Although forest recovery after disturbance such as logging can take decades, the legacy of forest clear-cut logging on key processes in tropical riparian ecosystems is mostly unknown. Here, we investigated how litter inputs (leaves, twigs, and reproductive parts) and storage, key processes for carbon and nutrient recycling and for forest and stream biota, are influenced by riparian vegetation undergoing succession (after 28 years from logging) through the comparison of reference and logged forest sites in the Cerrado biome. Litterfall was overall similar between forest types, but litterfall of twigs was twofold higher at logged than reference sites. Similarly, litter inputs from the bank to the stream (i.e., lateral inputs) and streambed storage were 50–60% higher at logged than reference sites. The higher litterfall observed in logged forests could be related to higher proportion of tree species that are characteristic of primary and secondary successional stages, including fast-growing and liana species, which often are more productive and common in anthropogenic areas. Our results showed that the legacy impact of clear-cut logging, even if residual woody vegetation is maintained in riparian buffers, can shift the type, quantity, and seasonality of litter subsidies to tropical streams. This knowledge should be considered within the context of management and conservation of communities and ecosystem processes in the forest-stream interfaces.     

5′ and 3′ SINE-PCR allows genotyping of pig families without cloning and sequencing steps

A microsatellite-containing clone, isolated from a pig Chromosome (Chr) 1-specific library was characterized by sequencing and computer analysis. The (CA)₁₇ microsatellite motif was located at the 3 end of a short interspersed element (SINE) sequence at the position normally occupied by the oligo (A) stretch. Further computer analysis indicated that 12% of published pig SINE sequences contain dinucleotide repeat motifs adjacent to their 3 ends. By performing PCR with a single SINE primer in combination with a panel of arbitrarily selected unique primers, we have demonstrated that, as in human, polymorphisms can be detected and typed in pig family DNAs. A large number of SINE primer x unique primer combinations have been screened for the ability to detect polymorphisms in pig reference family DNAs. This approach does not require prior sequence information other than that of the pig SINE. We have also found polymorphisms at the 5 ends of pig SINE sequences by similar methods, but with a primer facing out to the 5 end of the SINE.     

Doubling protected land area may be inefficient at preserving the extent of undeveloped land and could cause substantial regional shifts in land use

Projection of land use and land-cover change is highly uncertain yet drives critical estimates of carbon emissions, climate change, and food and bioenergy production. We use new, spatially explicit land availability data in conjunction with a model sensitivity analysis to estimate the effects of additional land protection on land use and land cover. The land availability data include protected land and agricultural suitability and is incorporated into the Moirai land data system for initializing the Global Change Analysis Model. Overall, decreasing land availability is relatively inefficient at preserving undeveloped land while having considerable regional land-use impacts. Current amounts of protected area have little effect on land and crop production estimates, but including the spatial distribution of unsuitable (i.e., unavailable) land dramatically shifts bioenergy production from high northern latitudes to the rest of the world, compared with uniform availability. This highlights the importance of spatial heterogeneity in understanding and managing land change. Approximately doubling the current protected area to emulate a 30% protected area target may avoid land conversion by 2050 of less than half the newly protected extent while reducing bioenergy feedstock land by 10.4% and cropland and grazed pasture by over 3%. Regional bioenergy land may be reduced (increased) by up to 46% (36%), cropland reduced by up to 61%, pasture reduced by up to 100%, and harvested forest reduced by up to 35%. Only a few regions show notable gains in some undeveloped land types of up to 36%. Half of the regions can reach the target using only unsuitable land, which would minimize impacts on agriculture but may not meet conservation goals. Rather than focusing on an area target, a more robust approach may be to carefully select newly protected land to meet well-defined conservation goals while minimizing impacts to agriculture.     

Treatment-resistant depression: definition,prevalence, detection,management, and investigational interventions

Treatment-resistant depression (TRD) is common and associated with multiple serious public health implications. A consensus definition of TRD with demonstrated predictive utility in terms of clinical decision-making and health outcomes does not currently exist. Instead, a plethora of definitions have been proposed, which vary significantly in their conceptual framework. The absence of a consensus definition hampers precise estimates of the prevalence of TRD, and also belies efforts to identify risk factors, prevention opportunities, and effective interventions. In addition, it results in heterogeneity in clinical practice decision-making, adversely affecting quality of care. The US Food and Drug Administration (FDA) and the European Medicines Agency (EMA) have adopted the most used definition of TRD (i.e., inadequate response to a minimum of two antidepressants despite adequacy of the treatment trial and adherence to treatment). It is currently estimated that at least 30% of persons with depression meet this definition. A significant percentage of persons with TRD are actually pseudo-resistant (e.g., due to inadequacy of treatment trials or non-adherence to treatment). Although multiple sociodemographic, clinical, treatment and contextual factors are known to negatively moderate response in persons with depression, very few factors are regarded as predictive of non-response across multiple modalities of treatment. Intravenous ketamine and intranasal esketamine (co-administered with an antidepressant) are established as efficacious in the management of TRD. Some second-generation antipsychotics (e.g., aripiprazole, brexpiprazole, cariprazine, quetiapine XR) are proven effective as adjunctive treatments to antidepressants in partial responders, but only the olanzapine-fluoxetine combination has been studied in FDA-defined TRD. Repetitive transcranial magnetic stimulation (TMS) is established as effective and FDA-approved for individuals with TRD, with accelerated theta-burst TMS also recently showing efficacy. Electroconvulsive therapy is regarded as an effective acute and maintenance intervention in TRD, with preliminary evidence suggesting non-inferiority to acute intravenous ketamine. Evidence for extending antidepressant trial, medication switching and combining antidepressants is mixed. Manual-based psychotherapies are not established as efficacious on their own in TRD, but offer significant symptomatic relief when added to conventional antidepressants. Digital therapeutics are under study and represent a potential future clinical vista in this population.     

HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY OF PHYTOPLANKTON PIGMENTS USING A POLYMERIC REVERSED-PHASE C18 COLUMN1

A high-performance liquid chromatographic (HPLC) method is described that allows improved resolution of several chemotaxonomically significant phytoplankton pigments. The protocol, which employs two pumps and a modified Mantoura and Llewellyn (1983) solvent system, can be easily adapted for many HPLC systems currently in use. The most unique aspect of the method is the use of a polymeric C₁₈ reversed phase HPLC column (VYDAC 201TP). In comparison to the monomeric C₁₈ columns typically used in the characterization of phytoplankton pigments, polymeric C₁₈ columns offer superior selectivity for structurally similar compounds. The protocol was evaluated for the ability to resolve most of the phytoplankton pigments of diagnostic importance using algal cultures from nine classes. Pigment pairs that were resolved by the method include a) lutein and zeaxanthin, b) neoxanthin and 19′-hexanoyloxyfucoxanthin, and c) α-carotene and β-carotene, and partial resolution of chlorophyll c₁ and chlorophyll c₂.     

LEAF GAS EXCHANGE IN QUERCUS MACROCARPA (FAGACEAE): RAPID STOMATAL RESPONSES TO VARIABILITY IN SUNLIGHT IN A TREE GROWTH FORM

Responses in net photosynthesis (A), stomatal conductance to water vapor (g), and leaf xylem pressure potential (ψ) were measured in the deciduous tree Quercus macrocarpa during alternating periods of sun (photosynthetic photon flux, PPF > 1,500 μmol m^-2 sec^-1) and shade (ca. 350 μmol m^-2 sec^-1 simulating cloud cover). Measurements were made on trees growing at the gallery forest-prairie edge on the Konza Prairie Research Natural Area in northeast Kansas. The region is near the westernmost extension of the range of Q. macrocarpa where this species experiences significant seasonal water stress (minimum ψ < -2.9 MPa). Quercus macrocarpa was chosen for study because it has relatively high A (15 μmol m^-2 sec^-1) and g (300 mmol m^-2 sec^-1) in contrast to the deciduous and evergreen subalpine trees previously studied. Both trees and large saplings of Q. macrocarpa responded to alternating several minute periods of sun and shade with relatively rapid changes in A and g. Reductions in g (110 mmol m^-2 sec^-1) during shade periods lowered transpirational water losses (E) by 13% (and reduced A by 5%) relative to estimates of A and E made assuming g remained constant. Partial stomatal closure during shade was correlated with moderate enhancement in ψ (0.31 MPa) in Q. macrocarpa. However, greater increases in ψ were measured in adjacent prairie grasses exposed to similar periods of shade (0.72 MPa in Andropogon gerardii, 0.61 MPa in Sorghastrum nutans). Reduced variability in ψ in tree growth forms may reflect greater buffering of water relations associated with the large size of trees, the amount of tissue devoted to water storage, and differences in hydraulic resistance relative to herbs. Nonetheless, the gas exchange and water relations responses in Q. macrocarpa were much more similar to those previously measured in herbaceous subalpine and grassland species than to those documented for subalpine trees. Thus, rapid gas exchange responses to variable PPF may also occur in tree growth forms.