En route to early diagnosis of Alzheimer's disease--are we there yet?

As therapeutics for Alzheimer's disease (AD) become available, it will become increasingly important to develop accurate and reliable tools for its early diagnosis. A recent paper by Georganopoulou et al. suggests that nanobiotechnology could help to overcome the limitations with the current diagnostic methods. The paper introduces a nanoparticle-based assay using antibodies that are specific for amyloid beta-protein (Abeta) oligomers with sub-femtomolar sensitivity. This assay appears to be more specific for AD than previous ELISA-based work and, if specificity of the assay for Abeta oligomers can be established, the method developed might provide a sensitive, reliable diagnostic tool for AD.     

Isolation,identification and subtyping of Campylobacter: Where to from here?

Campylobacter species are widely regarded as the most frequent bacterial cause of gastroenteritis in humans worldwide. Their main transmission routes are via contaminated food and water. For interventions to be effective, methods for the detection, identification and epidemiological subtyping must be sensitive, accurate and rapid. As yet, methods are not perfect, although several significant advances have been made in these areas in recent years. This paper provides a brief review and commentary on the current state of the art in the hope that it will help provide context for others in selecting, improving or developing these vital tools for research and diagnoses.     

Electroantennogram (EAG) responses of Microplitis croceipes and Cotesia marginiventris and their lepidopteran hosts to a wide array of odor stimuli: Correlation between EAG response and degree of host specificity?

In order to test whether the electroantennogram (EAG) response spectrum of an insect correlates to its degree of host specificity, we recorded EAG responses of two parasitoid species with different degrees of host specificity, Microplitis croceipes (specialist) and Cotesia marginiventris (generalist), to a wide array of odor stimuli including compounds representing green leaf volatiles (GLVs), herbivore-induced plant volatiles (HIPV), ecologically irrelevant (not used by the parasitoid species and their hosts for host location) plant volatiles, and host-specific odor stimuli (host sex pheromones, and extracts of host caterpillar body and frass). We also tested the EAG responses of female moths of the caterpillar hosts of the parasitoids, Heliothis virescens and Spodoptera exigua, to some of the odor stimuli. We hypothesized that the specialist parasitoid will have a narrower EAG response spectrum than the generalist, and that the two lepidopteran species, which are similar in their host plant use, will show similar EAG response spectra to plant volatiles. As predicted, the specialist parasitoid showed greater EAG responses than the generalist to host-specific odor and one HIPV (cis-3-hexenyl butyrate), whereas the generalist showed relatively greater EAG responses to the GLVs and unrelated plant volatiles. We detected no differences in the EAG responses of H. virescens and S. exigua to any of the tested odor.     

P-factor,a developmental hormone of Penicillium cyclopium?

From the mycelium of Penicillium cyclopium a biologically active fraction (P-factor) was isolated, which increases conidiation and the formation of the benzodiazepine alkaloids cyclopenin and cyclopenol. Its activity was determined by measuring the increase of alkaloid formation in strain SM 72. On a preparative scale P-factor preparations were obtained from fermenter-grown hyphae of mutant dev 63 by extraction with water at 120°. P-factor is strongly hydrophilic but it is not a protein. It was active if added during conidiospore germination and early growth phase, causing an acceleration of protein biosynthesis. The action on alkaloid biosynthesis and sporulation is indirect and resembles that of a developmental hormone.     

Are the diatoms Navicula sp. and Thalassiosira fluviatilis suitable to be fed to the benthic harpacticoid copepod Tisbe biminiensis?

The objective of this study was to compare the influence of the diets of two diatoms, Navicula sp. (benthic) and Thalassiosira fluviatilis (planctonic), on the development, fecundity and survival of the harpacticoid copepod Tisbe biminiensis. In order to determine the optimal concentration of food, 35 egg-bearing females were submitted to six algal concentrations and controls (without food). After 24 h, the content of the recipients was fixed with 4% formalin and then fecal pellets produced by each female were counted and measured. The larval development was studied by surveying 50 nauplii on each diet individually until the adult stage, at intervals of 6 h. The cast exoskeletons were removed to count the number of segments and for measurement. The fecundity was obtained counting the naupliar production every 48 h of groups containing 10 females in different algal concentrations in both diets. The diet influence on fecundity was tested by submitting four groups of 10 females fed on optimal algal concentrations based on the fecal pellet experiments. In the Navicula sp. concentration of 0.4 μg Chl-a/ml, considered to be optimal for fecal pellets production, the diatoms were shown toxic, resulting in a low survival rate and inhibiting the egg production of copepods. The optimal concentration considering fecundity was estimated to be 0.1 μg Chl-a/ml for both diets. Copepods fed on Navicula sp. presented a faster development rate and higher naupliar production compared to copepods fed on T. fluviatilis. Size and survival did not vary significantly among diets. The algal concentration interfered significantly in the reproductive success of females. Both very low and very high algal concentrations reduced reproductive success. Concluding, the benthic diatom Navicula sp. was more favorable to the copepod T. biminiensis than the planktonic diatom T. fluviatilis.     

Can roadside habitat lead monarchs on a route to recovery?

The Eastern North American monarch butterfly population has severely declined over the past decade. The decreasing availability of larval host plants (milkweeds) due to the use of herbicide-tolerant crops has been implicated in this decline. Roadsides could provide additional habitat for monarchs. In this study we document the occurrence of milkweed and monarchs on roadsides, and discuss whether roadsides are appropriate targets for monarch habitat restoration. We sampled roadside rights-of-way in the Upper Midwestern U.S. during the summer of 2015 to estimate the abundance, distribution, and diversity of milkweeds and the extent to which monarchs use these milkweeds. We then compared monarch densities in roadsides to other habitat types and modelled immature monarch densities based on several site characteristics. Our findings suggest that roadsides have conservation potential for monarchs, especially when other habitat is scarce and if wildlife-friendly management practices are enacted. Milkweeds were found on ~60% of roadside transects. Asclepias syriaca was the most common of the seven species encountered, occurring on 97% of transects with milkweed. Immature monarchs were observed in roadsides, but in lower densities than other habitats during the same time period. At lower milkweed densities, immature monarch density per unit area is positively correlated with milkweed density. However, milkweed density weakens as a predictor of immature monarch density over ~0.6 plants per m², possibly indicating a saturation effect.     

How does a Psittacanthus robustus Mart. population structure relate to a Vochysia thyrsoidea Pohl. host population?

Distribution of parasitic plants is directly linked with the distribution of host species and behavioral patterns of seed dispersers. Psittacanthus robustus (Loranthaceae) is a neotropical hemiparasite that mainly colonizes species of the family Vochysiaceae. Vochysia thyrsoidea is the main host of P. robustus and is commonly found in areas of cerrado rupestre (rocky savanna), an abundant vegetation in our study site. We conducted the study in the ecological park Parque Ecológico Quedas do Rio Bonito (PEQRB), over an area of 2.82 ha of cerrado rupestre. The objective of this work was to investigate population structure, parasitic behavior (mistletoe grip height and circumference of host branch), and spatial distribution of Psittacanthus robustus on a population of Vochysia thyrsoidea. We sampled 267 V. thyrsoidea individuals and found that the population had a random distribution pattern. Seventy-nine individuals (29.6% of the sample population) hosted the hemiparasite, to a total of 193 P. robustus individuals. The number of mistletoe individuals per host plant ranged between 1 and 12. The V. thyrsoidea individuals most infested with mistletoes were those reaching greater heights. The correlation between height of host plant and preferred grip height was highly significant, with the preferred grip height being the uppermost portions of host plants. The crown size of P. robustus individuals ranged between 10 and 230 cm. The main disperser of P. robustus fruit was found to be swallow-tanager Tersina viridis viridis. Its activities led to a clumped pattern of spatial distribution of the hemiparasite along with higher infestation in larger trees.     

Mutations and addiction to EGFR: the Achilles ‘heal’ of lung cancers?

The epidermal growth factor receptor (EGFR) gene product is a receptor tyrosine kinase (TK) that affects many important downstream pathways. The recent finding that mutations in EGFR predict the response of lung cancers to therapies that target the TK domain of the gene product has generated considerable interest. The mutations are associated with adenocarcinoma histology, oriental origin, female gender and never-smoker status. Most mutations target structures in the TK domain that appear to be essential for the phosphorylation function of the gene. Cancer cells with mutant EGFR genes might become physiologically dependent on the continued activity of the gene for the maintenance of their malignant phenotype; however, this might also be a target for therapy.     

Is decreased generalized immunity a cost of Bt resistance in cabbage loopers Trichoplusia ni?

We studied the immune response to Bacillus thuringiensis kurstaki (Btk) in susceptible (Bt-RS) and resistant (Bt-R) Trichoplusia ni after exposure to low doses of Btk and injection with Escherichia coli. We measured the levels of resistance, the expression profiles of hemolymph proteins, the phenoloxidase (PO) activity, and the differential number of circulating hemocytes in resistant and susceptible individuals. Individuals from the Bt-RS line became more resistant following a previous exposure to sub lethal concentrations of Btk, but the resistance to Btk of the Bt-R line did not change significantly. Similarly the Bt-R strain showed no significant changes in any of the potential immune responses, hemolymph protein levels or PO activity. The number of circulating hemocytes was significantly lower in the Bt-R strain than in the Bt-RS strain. Exposure to Btk decreased the hemocyte counts and reduced PO activity of Bt-RS larvae. Hemolymph protein concentrations also declined significantly in the susceptible larvae continually exposed to Btk. Seven peptides with antibacterial activity were identified in the hemolymph of Bt-RS larvae after exposure to Btk and five were found in the Bt-R larvae. When exposed to a low level Bt challenge the susceptible strain increases in tolerance and there are concomitant reductions in hemolymph protein concentrations, PO activity and the number of circulating hemocytes.     

Zn- and Cu-thioneins: a functional classification for metallothioneins?

This report intends to provide the reader with a deeper insight in the chemical, and extensively biological, characteristics of the metallothionein (MT) system. We have devoted nearly 20 years to the study of MTs and this has allowed us to form what we believe is a more complete picture of this peculiar family of metalloproteins. At the beginning of the 1990s, the landscape of this field was quite different from the overall picture we have now. Many researchers have contributed to the readjustment of this part of scientific knowledge. In our case, we implemented a unified method for obtaining MTs, for characterizing their metal-binding features, and for applying a unified research rationale. All this has helped to enlarge the initial picture that was mainly dominated by mammalian MT1/MT2 and yeast Cup1, by introducing approximately 20 new MTs. It has also allowed some characteristics to be clarified and examined in more detail, such as the cooperativity or the coexistence of multiple species in the metal-substitution reactions, the availability of Ag(I) or Cd(II) for use as respective probes for the Cu(I) and Zn(II) binding sites, the participation of chloride or sulfide ligands in the metal coordination spheres, and the feasibility of using in vitro data as representative of in vivo scenarios. Overall, the results yield enough data to consider new criteria for a proposal of classification of MTs based on MT metal-binding features, which complements the previous classifications, and that can shed light on the still controversial physiological functions of this peculiar superfamily of metalloproteins.     

Prolonged clonal growth: escape route or route to extinction?

Many plant species have the capability to reproduce sexually as well as clonally. The balance between clonal reproduction and sexual reproduction varies between different species. It was estimated that 66.5% of all central European flora may form independent but genetically identical daughter plants. Also within species there is great variation in the ratio clonal/sexual reproduction. Clonal reproduction can be considered as an alternative life cycle loop that allows persistence of a species in the absence of the ability to complete the normal life cycle (i.e. seed production, germination and recruitment). Plant populations exhibiting prolonged clonal growth have been referred to as 'remnant populations'. A remnant population in general is defined as "a population capable of persistence during extended time periods despite a negative population growth rate (λ<1) due to longlived life stages and life cycles, including loops, that allow population persistence without completion of the whole life cycle". Here we argue that prolonged and nearly exclusive clonal growth through environmental suppression of sexual reproduction can ultimately lead to local sexual extinction and to monoclonal populations of a species, and that this may imply significant consequences for population viability. Especially obligate or mainly outcrossing clonal plant species may be vulnerable for sexual extinction. We argue that the consequences of reduced sexual recruitment in clonally propagating plants may be understudied and underestimated and that a re-evaluation of current ideas on clonality may be necessary.     

In vitro susceptibilities of Neoscytalidium spp. sequence types to antifungal agents and antimicrobial photodynamic treatment with phenothiazinium photosensitizers

Neoscytalidium spp. are ascomycetous fungi consisting of pigmented and hyaline varieties both able to cause skin and nail infection. Their color-based identification is inaccurate and may compromise the outcome of the studies with these fungi. The aim of this study was to genotype 32 isolates morphologically identified as Neoscytalidiumdimidiatum or N. dimidiatum var. hyalinum by multilocus sequence typing (MLST), differentiate the two varieties by their sequence types, evaluate their susceptibility to seven commercial antifungal drugs [amphotericin B (AMB), voriconazole (VOR), terbinafine (TER), 5-flucytosine (5FC), ketoconazole (KET), fluconazole (FLU), and caspofungin (CAS)], and also to the antimicrobial photodynamic treatment (APDT) with the phenothiazinium photosensitizers (PS) methylene blue (MB), new methylene blue (NMBN), toluidine blue O (TBO) and the pentacyclic derivative S137. The efficacy of each PS was determined, initially, based on its minimal inhibitory concentration (MIC). Additionally, the APDT effects with each PS on the survival of ungerminated and germinated arthroconidia of both varieties were evaluated. Seven loci of Neoscytalidium spp. were sequenced on MLST revealing eight polymorphic sites and six sequence types (ST). All N. dimidiatum var. hyalinum isolates were clustered in a single ST. AMB, VOR and TER were the most effective antifungal agents against both varieties. The hyaline variety isolates were much less tolerant to the azoles than the isolates of the pigmented variety. APDT with S137 showed the lowest MIC for all the isolates of both varieties. APDT with all the PS killed both ungerminated and germinated arthroconidia of both varieties reducing the survival up to 5 logs. Isolates of the hyaline variety were also less tolerant to APDT. APDT with the four PS also increased the plasma membrane permeability of arthroconidia of both varieties but only NMBN and S137 caused peroxidation of the membrane lipids.     

A Comparison of the Membrane Binding Properties of C1B Domains of PKCγ, PKCδ, and PKC?

The C1 domains of classical and novel PKCs mediate their diacylglycerol-dependent translocation. Using fluorescence resonance energy transfer, we studied the contribution of different negatively charged phospholipids and diacylglycerols to membrane binding. Three different C1B domains of PKCs were studied (the classical γ, and the novel δ and ?), together with different lipid mixtures containing three types of acidic phospholipids and three types of activating diacylglycerols. The results show that C1Bγ and C1B? exhibit a higher affinity to bind to vesicles containing 1-palmitoyl-2-oleoyl-sn-phosphatidic acid, 1-palmitoyl-2-oleoyl-sn-phoshatidylserine, or 1-palmitoyl-2-oleoyl-sn-phosphatidylglycerol, with C1B? being the most relevant case because its affinity for POPA-containing vesicles increased by almost two orders of magnitude. When the effect of the diacylglycerol fatty acid composition on membrane binding was studied, the C1B? domain showed the highest binding affinity to membranes containing 1-stearoyl-oleoyl-sn-glycerol or 1,2-sn-dioleoylglycerol with POPA as the acidic phospholipid. Of the three diacylglycerols used in this study, 1,2-sn-dioleoylglycerol and 1-stearoyl-oleoyl-sn-glycerol showed the highest affinities for each isoenzyme, whereas 1,2-sn-dipalmitoylglycerol; showed the lowest affinity. DSC experiments showed this to be a consequence of the nonfluid conditions of 1,2-sn-dipalmitoylglycerol;-containing systems.     

MUC genes: a superfamily of genes? Towards a functional classification of human apomucins

The MUC genes encode epithelial mucins. Eight different human genes have been well characterized, and two others identified more recently. Among them, a family of four genes, expressed in the respiratory and digestive tracts, is clustered to chromosome 11p15.5; and these genes encode gel-forming mucins which are structurally related to the superfamily of cystine-knot growth factors. A second group is composed of three independent genes encoding various isoforms of mucins including membrane-bound mucins associated to carcinomas. In this second group, MUC3 and MUC4 encode large apomucins containing EGF-like domains.     

Does sea level rise influence propagule establishment, early growth and physiology of Kandelia candel and Bruguiera gymnorrhiza?

Responses of Kandelia candel and Bruguiera gymnorrhiza in loamy-sandy (coarse) and silty (fine) soils to water level rise and prolonged inundation were investigated under mesocosm and field conditions. Acidity due to simulated sea level rise of 30 cm was more serious in fine soil than that in coarse soil. Propagules of K. candel had more rapid establishments under high water level and prolonged inundation, but establishments of B. gymnorrhiza were not significantly influenced by tide condition. Water level rise of 30 cm and prolonged inundation stimulated early growth especially in stem height increments during the first 2 months for K. candel and B. gymnorrhiza. However, relative growth rates (RGRs) during the second 2 months did not significantly change for K. candel and even decreased for B. gymnorrhiza with water level rise. The root/shoot biomass ratio in both K. candel and B. gymnorrhiza treated with high water level was significantly lower than that treated with low water level, especially in coarse soil. Biomass percentages of coarse roots of K. candel and B. gymnorrhiza seedlings significantly increased with water level rise. Water level rise led to decreases in Chl. a/b ratios in leaves of K. candel seedlings, but the ratios did not significantly change with water level for B. gymnorrhiza. Decreases in RGRs of B. gymnorrhiza were due to decreases in total leaf area resulting from increases in stomatal density. Contents of N and P in roots tended to increase with water level rise and prolonged inundation. Under both high and low water levels, all propagules of K. candel and B. gymnorrhiza successfully established and the seedlings survived throughout the mesocosm experiment. For the field trial, K. candel seedlings had similar high survival rates of over 90%, while B. gymnorrhiza seedlings had much less survival in lower intertidal zones than in upper intertidal zones. These differences were ascribed to stronger tidal action and more sedimentation in the field than under mesocosm conditions. Survived seedlings of K. candel and B. gymnorrhiza from both propagule plantation and seedling transplantation in field trial also showed higher stem increments during the first 4 months in lower intertidal zones.