Changes in water quality related to permafrost thaw may significantly impact zooplankton in small Arctic lakes.

Rising temperatures are leading to permafrost thaw over vast areas of the northern hemisphere. In the Canadian Arctic, permafrost degradation is causing significant changes in surface water quality due to the release of solutes that can alter conductivity, water clarity, and nutrient levels. For this study, we examined how changes in water quality associated with permafrost thaw might impact zooplankton, a group of organisms that play an important role in the food web of Arctic lakes. We conducted a biological and water quality survey of 37 lakes in the Mackenzie Delta region of Canada's Northwest Territories. We then used this data set to develop models linking variation in the abundance, diversity, and evenness of zooplankton communities to physicochemical, biological, and spatial variables. Subsequently, we used these models to predict how zooplankton communities might respond as water quality is altered by permafrost thaw. Our models explained 47%, 68%, and 69% of the variation in zooplankton abundance, diversity, and evenness, respectively. Importantly, the most parsimonious models always included variables affected by permafrost thaw, such as calcium and conductivity. Predictions based on our models suggest significant increases in zooplankton abundance (1.6-3.6 fold) and decreases in diversity (1.2-1.7 fold) and evenness (1.1-1.4 fold) in response to water quality changes associated with permafrost thaw. These changes are in line with those described for significant perturbations such as eutrophication, acidification, and the introduction of exotic species such as the spiny water flea (Bythotrephes). Given their important role in aquatic food webs, we expect these changes in zooplankton communities will have ramifications for organisms at higher (fish) and lower (phytoplankton) trophic positions in Arctic lakes.

Laboratory Evolution of Metalloid Reductase Substrate Recognition and Nanoparticle Product Size.

Glutathione reductase-like metalloid reductase (GRLMR) is an enzyme that reduces selenodiglutathione (GS-Se-SG), forming zerovalent Se nanoparticles (SeNPs). Error-prone polymerase chain reaction was used to create a library of ∼10,000 GRLMR variants. The library was expressed in BL21Escherichia coli in liquid culture with 50 mM of SeO32- present, under the hypothesis that the enzyme variants with improved GS-Se-SG reduction kinetics would emerge. The selection resulted in a GRLMR variant with two mutations. One of the mutations (D-E) lacks an obvious functional role, whereas the other mutation is L-H within 5 Šof the enzyme active site. This mutation places a second H residue within 5 Šof an active site dicysteine. This GRLMR variant was characterized for NADPH-dependent reduction of GS-Se-SG, GSSG, SeO32-, SeO42-, GS-Te-SG, and TeO32-. The evolved enzyme demonstrated enhanced reduction of SeO32- and gained the ability to reduce SeO42-. This variant is named selenium reductase (SeR) because of its emergent broad activity for a wide variety of Se substrates, whereas the parent enzyme was specific for GS-Se-SG. This study overall suggests that new biosynthetic routes are possible for inorganic nanomaterials using laboratory-directed evolution methods.

Cloneable inorganic nanoparticles.

When a defined protein/peptide (or combinations thereof) control and define the synthesis of an inorganic nanoparticle, the result is a cloneable NanoParticle (cNP). This is because the protein sequence/structure/function is encoded in DNA, and therefore the physicochemical properties of the nanoparticle are also encoded in DNA. Thus the cloneable nanoparticle paradigm can be considered as an extension of the central dogma of molecular biology (e.g. DNA → mRNA → protein → cNP); modifications to the DNA encoding a cNP can modify the resulting properties of the cNP. Inorganic ion oxidoreductases (e.g., mercuric reductase, tellurite reductase, etc.) can select and reduce specific inorganic oxyanions and coordination complexes, creating zerovalent precipitates. Other proteins/peptides (often genetically concatenated to the parent oxidoreductase) serve as ligands, directing the size, shape, crystal structure and other properties of the nanoparticle. The DNA encoding a cNP can be recombinantly transferred into any organism. Ideally, this enables recombinant production of cNPs with the same defined physiochemical properties. Such cNPs are of interest for applications ranging from molecular imaging, bio-remediation, catalysis, and biomining. In this Feature Article we detail and define the cNP concept, and retrace the story of our creation of a cloneable Se NanoParticle (cSeNP). We also describe our more preliminary work that we expect to result in cloneable semiconductor quantum dots, cloneable Te nanoparticles, and other cNP formulations. We highlight the application of cNPs in cellular electron microscopy and compare this approach to other cloneable imaging contrast approaches.

Providing social support to cancer patients: a look at alternative methods.

One way in which the psychosocial needs of cancer patients can be addressed is through support groups, which are often recommended to patients by healthcare professionals. The present study aimed to assess the effectiveness of Gilda's Club in meeting the needs of cancer patients during their first year of membership and whether their experience with this organization was a positive one. Thirty Gilda's Club members with cancer completed a semi-structured quantitative and qualitative questionnaire. Findings revealed over half of the sample participated in some type of support group and the majority of participants reported that the supports groups were helpful, with only 10% of participants reporting that they did not receive help from the support group. Qualitative data revealed that the most common sources of support outside of Gilda's Club were family, friends, and church. Since their initial contact with Gilda's Club one year ago, 60% reported no change in their level of depression, 20% reported more depression, and 20% reported less depression. Most participants (57%) had received no counseling for depression, and only 20% were still receiving counseling for depression. Qualitative data also revealed the majority of participants had overall positive impressions of Gilda's club.

Treating Anorexia Nervosa and Bulimia Nervosa.

Research on the treatment of eating disorders is a relatively new field, dating back approximately 20 years (Peterson & Mitchell, 1999). The purpose of this article is to describe the most widely used treatments for anorexia nervosa (AN) and bulimia nervosa (BN) and review the existing literature on the effectiveness of the identified treatments. Specifically, this article examines the effectiveness of cognitive-behavioral therapy, family therapy, interpersonal therapy, and pharmacotherapy in the treatment of AN and BN. Each of the reviewed treatment modalities has some level of effectiveness, either alone or in conjunction with another treatment approach, in treating either AN or BN.