Biotin- and Glycoprotein-Coated Microspheres as Surrogates for Studying Filtration Removal of Cryptosporidium parvum in a Granular Limestone Aquifer Medium

Members of the genus Cryptosporidium are waterborne protozoa of great health concern. Many studies have attempted to find appropriate surrogates for assessing Cryptosporidium filtration removal in porous media. In this study, we evaluated the filtration of Cryptosporidium parvum in granular limestone medium by the use of biotin- and glycoprotein-coated carboxylated polystyrene microspheres (CPMs) as surrogates. Column experiments were carried out with core material taken from a managed aquifer recharge site in Adelaide, Australia. For the experiments with injection of a single type of particle, we observed the total removal of the oocysts and glycoprotein-coated CPMs, a 4.6- to 6.3-log₁₀ reduction of biotin-coated CPMs, and a 2.6-log₁₀ reduction of unmodified CPMs. When two different types of particles were simultaneously injected, glycoprotein-coated CPMs showed a 5.3-log₁₀ reduction, while the uncoated CPMs displayed a 3.7-log₁₀ reduction, probably due to particle-particle interactions. Our results confirm that glycoprotein-coated CPMs are the most accurate surrogates for C. parvum; biotin-coated CPMs are slightly more conservative, while unmodified CPMs are markedly overly conservative for predicting C. parvum removal in granular limestone medium. The total removal of C. parvum observed in our study suggests that granular limestone medium is very effective for the filtration removal of C. parvum and could potentially be used for the pretreatment of drinking water and aquifer storage recovery of recycled water.     

Does mixed-species flocking influence how birds respond to a gradient of land-use intensity?

Conservation biology is increasingly concerned with preserving interactions among species such as mutualisms in landscapes facing anthropogenic change. We investigated how one kind of mutualism, mixed-species bird flocks, influences the way in which birds respond to different habitat types of varying land-use intensity. We use data from a well-replicated, large-scale study in Sri Lanka and the Western Ghats of India, in which flocks were observed inside forest reserves, in ‘buffer zones'' of degraded forest or timber plantations, and in areas of intensive agriculture. We find flocks affected the responses of birds in three ways: (i) species with high propensity to flock were more sensitive to land use; (ii) different flock types, dominated by different flock leaders, varied in their sensitivity to land use and because following species have distinct preferences for leaders, this can have a cascading effect on followers'' habitat selection; and (iii) those forest-interior species that remain outside of forests were found more inside flocks than would be expected by chance, as they may use flocks more in suboptimal habitat. We conclude that designing policies to protect flocks and their leading species may be an effective way to conserve multiple bird species in mixed forest and agricultural landscapes.     

A validated LC-MS/MS assay for quantification of 24(S)-hydroxycholesterol in plasma and cerebrospinal fluid

24(S)-hydroxycholesterol [24(S)-HC] is a cholesterol metabolite that is formed almost exclusively in the brain. The concentrations of 24(S)-HC in cerebrospinal fluid (CSF) and/or plasma might be a sensitive marker of altered cholesterol metabolism in the CNS. A highly sensitive 2D-LC-MS/MS assay was developed for the quantification of 24(S)-HC in human plasma and CSF. In the development of an assay for 24(S)-HC in CSF, significant nonspecific binding of 24(S)-HC was observed and resolved with the addition of 2.5% 2-hydroxypropyl-β-cyclodextrin (HP-β-CD) into CSF samples. The sample preparation consists of liquid-liquid extraction with methyl-tert-butyl ether and derivatization with nicotinic acid. Good linearity was observed in a range from 1 to 200 ng/ml and from 0.025 to 5 ng/ml, for plasma and CSF, respectively. Acceptable precision and accuracy were obtained for concentrations over the calibration curve ranges. Stability of 24(S)-HC was reported under a variety of storage conditions. This method has been successfully applied to support a National Institutes of Health-sponsored clinical trial of HP-β-CD in Niemann-Pick type C1 patients, in which 24(S)-HC is used as a pharmacodynamic biomarker.     

GSK-3β dysregulation contributes to parkinson's-like pathophysiology with associated region-specific phosphorylation and accumulation of tau and α-synuclein

Aberrant posttranslational modifications (PTMs) of proteins, namely phosphorylation, induce abnormalities in the biological properties of recipient proteins, underlying neurological diseases including Parkinson''s disease (PD). Genome-wide studies link genes encoding α-synuclein (α-Syn) and Tau as two of the most important in the genesis of PD. Although several kinases are known to phosphorylate α-Syn and Tau, we focused our analysis on GSK-3β because of its accepted role in phosphorylating Tau and to increasing evidence supporting a strong biophysical relationship between α-Syn and Tau in PD. Therefore, we investigated transgenic mice, which express a point mutant (S9A) of human GSK-3β. GSK-3β-S9A is capable of activation through endogenous natural signaling events, yet is unable to become inactivated through phosphorylation at serine-9. We used behavioral, biochemical, and in vitro analysis to assess the contributions of GSK-3β to both α-Syn and Tau phosphorylation. Behavioral studies revealed progressive age-dependent impairment of motor function, accompanied by loss of tyrosine hydroxylase-positive (TH+ DA-neurons) neurons and dopamine production in the oldest age group. Magnetic resonance imaging revealed deterioration of the substantia nigra in aged mice, a characteristic feature of PD patients. At the molecular level, kinase-active p-GSK-3β-Y216 was seen at all ages throughout the brain, yet elevated levels of p-α-Syn-S129 and p-Tau (S396/404) were found to increase with age exclusively in TH+ DA-neurons of the midbrain. p-GSK-3β-Y216 colocalized with p-Tau and p-α-Syn-S129. In vitro kinase assays showed that recombinant human GSK-3β directly phosphorylated α-Syn at a single site, Ser129, in addition to its known ability to phosphorylate Tau. Moreover, α-Syn and Tau together cooperated with one another to increase the magnitude or rate of phosphorylation of the other by GSK-3β. Together, these data establish a novel upstream role for GSK-3β as one of several kinases associated with PTMs of key proteins known to be causal in PD.After Alzheimer''s disease (AD), Parkinson''s disease (PD) is the second most prevalent neurodegenerative disease, characterized by selective loss of TH+ DA-neurons of substantia nigra (SN) with diminished production of dopamine (DA).¹ Genome-wide studies have identified SNCA and MAPT, genes encoding α-synuclein (α-Syn) and Tau, respectively, as having strong association to the genesis of PD.^{2, 3, 4} Although the precise etiology of PD remains a mystery, SNCA amplifications and mutations directly link α-Syn dysfunction to disease causation,^{5, 6} firmly establishing a role for α-Syn in sporadic and familial PD, respectively. α-Syn can be phosphorylated at several sites,⁷ and the predominance of α-Syn phosphorylated at serine 129 (S129) in Lewy bodies⁸ suggests its phosphorylation status at S129 has an important pathological role. Various PD models have shown that phosphorylation at S219 enhanced α-syn toxicity resulting in accelerated motor abnormalities and loss of DA-neurons.^{9, 10}Fewer studies have examined the role of Tau (or p-Tau) in PD, but interest in the field has grown since completion of several genome-wide association studies. p-Tau has been found to colocalize with α-Syn in tissue from sporadic PD and dementia with Lewy bodies.¹¹ We^{12, 13} and others^14,15 have also identified p-Tau in different brain regions of PD, dementia with Lewy bodies, and AD. High levels of p-Tau have also been observed in vivo in several toxin^{16, 17, 18} and transgenic α-Syn models of PD,^19,20 suggesting that p-Tau may be an important common factor in the neurodegeneration of not only tauopathies but also of synucleinopathies, such as PD.^{21, 22, 23, 24} Most studies to date have focused on the formation and accumulation of Tau and p-Tau in idiopathic PD. Yet several studies have provided evidence that leucine-rich repeat kinase-2 (LRRK2), a kinase, that when mutated is involved in familial forms of PD, can directly interact with, and activate GSK-3β, resulting in increased p-TAU formation.^25,26Among the kinases known to hyperphosphorylate Tau, glycogen synthase kinase-3β (GSK-3β) may be the most important given its ability to phosphorylate Tau at the majority of its serine/threonine sites that cause associated toxicities in AD.^27,28 The importance of GSK-3β is illustrated in that it is embryonically lethal when knocked out in mice. Regulation of GSK-3β is tightly controlled through a series of direct and indirect measures. Direct regulation occurs through autophosphorylation at Tyr216,^29,30 resulting in a kinase-active form, p-GSK-3β-Y216, whereas phosphorylation at Ser9 results in a kinase-inactive state.³¹ The activity of GSK-3β can also be controlled indirectly through binding to inhibitory complexes with other cytoplasmic proteins,^32,33 or through Wnt-mediated sequestration into multivesicular bodies³⁴ resulting in the physical separation of GSK-3β from its cytoplasmic targets. Control of GSK-3β in the normal state is therefore tightly regulated, with its dysregulation and ensuing aberrant phosphorylation of targets being a common occurrence in many diverse diseases. Several studies have shown that GSK-3β is an important mediator in the injury and repair processes of neurons during cross-talk between DA-neurons and reactive astrocytes.^35,36 These studies showed that astrocyte-derived Wnt1 was capable of blocking GSK-3β activation, allowing the nuclear accumulation of β-catenin and subsequent gene expression of β-catenin-dependent targets essential for neuron survival and repair during chemical or metabolic insults. The importance of regulating the active/inactive states of GSK-3β in regard to neuronal stability is further supported through the analysis of conditional (Tet-inducible) transgenic mice expressing a dominant-negative GSK-3β-K85R mutant or expressing the GSK-3β-S9A mutant.^37,38 In these studies, post-natal Tet-regulated expression of either GSK-3β-K85R or GSK-3β-S9A led to neurodegeneration in the cortex, striatum, and hippocampus. What separates our TG PD model from the tet-inducible GSK-3β models is the spatial patterns of transgene expression, which is influenced by the choice of promoters. The Tet-inducible GSK-3β models are expressed using a CAMKII promoter with our human(h) GSK-3β-S9A transgene being expressed under the Thy-1 promoter. CAMKII-driven expression is limited to neurons originating from the forebrain with Thy-1 promoter-driven expression restricted to neurons in all or most brain regions.^39,40 Although promoter choice effecting tissue expression ultimately decides which regions show degeneration, the important message is that both inactive and hyperactive states of GSK-3β reduce neuronal viability.In our past studies in various in vitro and in vivo models of PD and in postmortem PD tissues, we have consistently observed a positive correlation between increased α-Syn and p-Tau levels with increased GSK-3β-Y216 (the kinase-active form of GSK-3β).^{12, 13, 16, 19, 20} In in vitro studies of MPTP-treated SH-SY5Y cells, blockade of GSK-3β with lithium, or with the highly selective non-ATP competitive inhibitor, TDZD-8, prevented the induction of p-GSK-3β-Y216, abolished p-Tau formation, and reversed the accumulation and aggregation of both p-Tau and α-Syn, averting cell death.¹⁶ Other studies using Rotenone or MPTP/MPP+ in chemical PD models, have shown similar results of decreased neuronal viability during treatments accompanied by dose- and time-dependent increases in GSK-3β activation, with decreased cytotoxicity detected when GSK-3β was inhibited or knocked-down through the use of GSK-3β-specific small molecule inhibitors or through RNAi.^41,42 This suggested to us that p-GSK-3β-Y216 may have a contributory role in the pathogenesis of PD. Using a mouse model overexpressing hGSK-3β-S9A under the Thy-1 promoter together with in vitro kinase assays allowed us to discern the role GSK-3β has in the development of PD-like pathology.⁴³ Analysis of our hGSK-3β-S9A mouse model showed here for the first time that upon aging, these mice develop the cardinal features of parkinsonism, manifested as impaired motor behavior, with associated loss of TH+ neurons, reduced DA production, and shrinkage of SN. Invitro kinase assays confirmed that hGSK-3β was capable of phosphorylating α-Syn on Serine 129 together with the known ability to phosphorylate Tau. Remarkably, both α-Syn and Tau influenced the rate and magnitude of phosphorylation of the other by GSK-3β indicating that an intimate physical relationship exist between the trio of PD related proteins. Together, these data shown indicate the importance of GSK-3β activation, in the behavioral and physiological development of PD like pathology in a new mouse model.     

An ana2/ctp/mud complex regulates spindle orientation in Drosophila neuroblasts

Drosophila neural stem cells, larval brain neuroblasts (NBs), align their mitotic spindles along the apical/basal axis during asymmetric cell division (ACD) to maintain the balance of self-renewal and differentiation. Here, we identified a protein complex composed of the tumor suppressor anastral spindle 2 (Ana2), a dynein light-chain protein Cut up (Ctp), and Mushroom body defect (Mud), which regulates mitotic spindle orientation. We isolated two ana2 alleles that displayed spindle misorientation and NB overgrowth phenotypes in larval brains. The centriolar protein Ana2 anchors Ctp to centrioles during ACD. The centriolar localization of Ctp is important for spindle orientation. Ana2 and Ctp localize Mud to the centrosomes and cell cortex and facilitate/maintain the association of Mud with Pins at the apical cortex. Our findings reveal that the centrosomal proteins Ana2 and Ctp regulate Mud function to?orient the mitotic spindle during NB asymmetric division.     

The multiple‐specificity landscape of modular peptide recognition domains

Modular protein interaction domains form the building blocks of eukaryotic signaling pathways. Many of them, known as peptide recognition domains, mediate protein interactions by recognizing short, linear amino acid stretches on the surface of their cognate partners with high specificity. Residues in these stretches are usually assumed to contribute independently to binding, which has led to a simplified understanding of protein interactions. Conversely, we observe in large binding peptide data sets that different residue positions display highly significant correlations for many domains in three distinct families (PDZ, SH3 and WW). These correlation patterns reveal a widespread occurrence of multiple binding specificities and give novel structural insights into protein interactions. For example, we predict a new binding mode of PDZ domains and structurally rationalize it for DLG1 PDZ1. We show that multiple specificity more accurately predicts protein interactions and experimentally validate some of the predictions for the human proteins DLG1 and SCRIB. Overall, our results reveal a rich specificity landscape in peptide recognition domains, suggesting new ways of encoding specificity in protein interaction networks.     

SIV DNA vaccine co-administered with IL-12 expression plasmid enhances CD8 SIV cellular immune responses in cynomolgus macaques

Current evidence suggests that a strong induced CD8 human immunodeficiency virus type 1 (HIV-1)-specific cell mediated immune response may be an important aspect of an HIV vaccine. The response rates and the magnitude of the CTL responses induced by current DNA vaccines in humans need to be improved and cellular immune responses to DNA vaccines can be enhanced in mice by co-delivering DNA plasmids expressing immune modulators. Two reported to work well in the mouse systems are interleukin (IL)-12 and CD40L. We sought to compare these molecular adjuvants in a primate model system. The cDNA for macaque IL-12 and CD40L were cloned into DNA vectors. Groups of cynomolgus macaques were immunized with 2 mg of plasmid expressing SIVgag alone or in combination with either IL-12 or CD40L. CD40L did not appear to enhance the cellular immune response to SIVgag antigen. However, more robust results were observed in animals co-injected with the IL-12 molecular adjuvant. The IL-12 expanded antigen-specific IFN-gamma positive effector cells as well as granzyme B production. The vaccine immune responses contained both a CD8 component as well a CD4 component. The adjuvanted DNA vaccines illustrate that IL-12 enhances a CD8 vaccine immune response, however, different cellular profiles.     

3-Thio-1,2,4-triazoles, novel somatostatin sst2/sst5 agonists

Novel 3-thio-1,2,4-triazoles have been obtained via a solution-phase parallel synthesis strategy, affording potent non-peptidic human somatostatin receptor subtypes 2 and 5 agonists.