Fingerprint Patterns in Huntington's Chorea and Parkinson's Disease

In the course of a continuing search for means of predicting Huntington''s chorea before the onset of neurological symptoms, a study of fingerprint patterns was undertaken, using the technique employed by Hodges and Simon in the investigation of patients with Wilson''s disease. Fingerprint patterns of 61 patients with Huntington''s chorea and 50 with Parkinson''s disease were compared with norms established by Scotland Yard. Although an increased incidence of the “whorl” pattern was seen in the left second and third fingers in patients with Huntington''s chorea, this finding could not be interpreted as having diagnostic or prognostic value as it was found also in some normal subjects and in occasional cases of Parkinson''s disease. The pattern supposedly characteristic of Wilson''s disease was also seen in persons with Huntington''s chorea.     

In vitro and in vivo neurotoxicity of prion protein oligomers

The mechanisms underlying prion-linked neurodegeneration remain to be elucidated, despite several recent advances in this field. Herein, we show that soluble, low molecular weight oligomers of the full-length prion protein (PrP), which possess characteristics of PrP to PrPsc conversion intermediates such as partial protease resistance, are neurotoxic in vitro on primary cultures of neurons and in vivo after subcortical stereotaxic injection. Monomeric PrP was not toxic. Insoluble, fibrillar forms of PrP exhibited no toxicity in vitro and were less toxic than their oligomeric counterparts in vivo. The toxicity was independent of PrP expression in the neurons both in vitro and in vivo for the PrP oligomers and in vivo for the PrP fibrils. Rescue experiments with antibodies showed that the exposure of the hydrophobic stretch of PrP at the oligomeric surface was necessary for toxicity. This study identifies toxic PrP species in vivo. It shows that PrP-induced neurodegeneration shares common mechanisms with other brain amyloidoses like Alzheimer disease and opens new avenues for neuroprotective intervention strategies of prion diseases targeting PrP oligomers.     

An organelle proteomic method to study neurotransmission-related proteins, applied to a neurodevelopmental model of schizophrenia

Limited information is currently available on molecular events that underlie schizophrenia-like behaviors in animal models. Accordingly, we developed an organelle proteomic approach enabling the study of neurotransmission-related proteins in the prefrontal cortex (PFC) of postpubertal (postnatal day 60 (PD60)) neonatally ventral hippocampal (nVH) lesioned rats, an extensively used neurodevelopmental model of schizophrenia-like behaviors. The PFC was chosen because of its purported role in the etiology of the disease. Statistical analysis of 392 reproducible spots on 2-D organelle proteomic patterns revealed significant changes in intensity of 18 proteinous spots in plasma membrane-enriched fractions obtained from postpubertal nVH lesioned rats compared to controls. Mass spectrometric analysis and database searching allowed the identification of a single protein in each of the nine differential spots, including proteins of low abundance, such as neurocalcin delta. Most of the identified dysregulated proteins, including clathrin light chain B, syntaxin binding protein 1b and visinin-like protein 1 are known to be linked to various neurotransmitter systems and to play key roles in plasma membrane receptor expression and recycling as well as synaptic vesicle exocytosis/recycling. Organelle proteomic approaches have hence proved to be most useful to identify key proteins linked to a given behavior in animal models of brain diseases.     

Effect of food deprivation on the ambulatory movement of the Colorado potato beetle,Leptinotarsa decemlineata

Modification of dispersal behaviour is a common response of insects to food and water deprivation. The literature suggests that different insects respond with different strategies: changing walking parameters, switching dispersal mode (walking to flight or vice versa), or changing the host searching path. The goal of this study was to add to the limited literature on the subject by investigating, whether the walking parameters of adult male Colorado potato beetles, Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae), change in response to food and water deprivation. Observations on the distance walked, the travel speed, and the frequency of walking bouts were carried out in laboratory arenas using motion monitoring equipment. Summer and overwintered beetles were exposed to short starvation periods (2, 4, 8, 24 h) and two ranges of long starvation periods (1, 2, 4, 8 days and 1, 2, 4, 8, 16, and 32 days). Only the longest food deprivation periods of 16 and 32 days significantly reduced the walking distance, speed, and frequency of walking bouts of summer beetles. No changes were observed with overwintered beetles. The tolerance of the beetles without access to water to the different periods of food deprivation was similar to that for beetles with water except after a starvation period of 32 days, when the travel speed of summer beetles was significantly reduced by 33%. The absence of increased walking parameters found in this study and earlier observations of increased flight frequency suggest that the strategy of summer beetles will be to change the dispersal mode from walking to flight and/or to change the walking host searching path. The same results of this study and earlier observations of a decrease in the mean frequency of daily flights suggest that the strategy of overwintered L. decemlineata, exposed to food deprivation, will be to change the host search walking path rather than the walking parameters themselves.     

Atmospheric pressure chemical ionization-mass spectrometry method to improve the determination of dansylated polyamines

Determination of polyamine pools is still a step impossible to circumvent in studies aimed at determining the pathophysiological role of natural polyamines. In addition, polyamine measurement in biological fluids and tissues may have clinical relevance, especially in cancer patients. Among the wide panel of analytical methods developed for the quantification of polyamines, high-performance liquid chromatographic (HPLC) separation of polyamines after derivatization with dansyl chloride remains the most commonly used method. In this work, we show that atmospheric pressure chemical ionization-mass spectrometry (MS) can be used to detect and quantify biologically relevant polyamines after dansylation, without chromatographic separation. Positive-ion mass spectra for each dansylated polyamine were generated after optimization by flow injection analysis (FIA). FIA coupled with MS detection by selected ion monitoring greatly increased the sensitivity of the polyamine detection. The method is linear over a wide range of polyamine concentrations and allows detection of quantities as low as 5 fmol. The FIA/MS method is about 50-fold more sensitive than the conventional HPLC/fluorimetry procedure. A good correlation (r>0.98) between these two methods was observed. The FIA/MS method notably reduces the time of analysis per sample to 1.5 min and turns out to be rapid, efficient, cost saving, reproducible, and sufficiently simple to allow its routine application.     

Glypican-1 is a vehicle for polyamine uptake in mammalian cells: a pivital role for nitrosothiol-derived nitric oxide

Polyamines (putrescine, spermidine, and spermine) are essential for growth and survival of all cells. When polyamine biosynthesis is inhibited, there is up-regulation of import. The mammalian polyamine transport system is unknown. We have previously shown that the heparan sulfate (HS) side chains of recycling glypican-1 (Gpc-1) can sequester spermine, that intracellular polyamine depletion increases the number of NO-sensitive N-unsubstituted glucosamines in HS, and that NO-dependent cleavage of HS at these sites is required for spermine uptake. The NO is derived from S-nitroso groups in the Gpc-1 protein. Using RNA interference technology as well as biochemical and microscopic techniques applied to both normal and uptake-deficient cells, we demonstrate that inhibition of Gpc-1 expression abrogates spermine uptake and intracellular delivery. In unperturbed cells, spermine and recycling Gpc-1 carrying HS chains rich in N-unsubstituted glucosamines were co-localized. By exposing cells to ascorbate, we induced release of NO from the S-nitroso groups, resulting in HS degradation and unloading of the sequestered polyamines as well as nuclear targeting of the deglycanated Gpc-1 protein. Polyamine uptake-deficient cells appear to have a defect in the NO release mechanism. We have managed to restore spermine uptake partially in these cells by providing spermine NONOate and ascorbate. The former bound to the HS chains of recycling Gpc-1 and S-nitrosylated the core protein. Ascorbate released NO, which degraded HS and liberated the bound spermine. Recycling HS proteoglycans of the glypican-type may be plasma membrane carriers for cargo taken up by caveolar endocytosis.     

Female mate copying in the guppy {Poecilia reticulata): age-dependent effects

Virtually all studies of mate choice to date have assumed thatfemales choose mates independent of one another. Social cues,however, such as the mate choice of conspecifics, may also playan important role in such decisions. Previous work has shownthat female guppies of similar age copy each other's choiceof mates. Here we examine the effect of relative age on matechoice copying in the guppy, Poecilia reticulata, and examinewhether younger individuals are more likely to copy the matechoice of older conspecifics than vice versa. Results indicatethat younger females copy the mate choice of older females,but older individuals do not appear to be influenced by themate choice of younger individuals.     

Phosphotyrosine binding-mediated oligomerization of downstream of tyrosine kinase (Dok)-1 and Dok-2 is involved in CD2-induced Dok phosphorylation

To date, five members of the downstream of tyrosine kinase (Dok) family have been characterized. In T cells, two members, Dok-1 and Dok-2, are expressed. CD2 or CD28 stimulation, but not CD3/TCR stimulation, induces Dok phosphorylation. Recent evidence suggests that they act as negative regulators of the CD2 and CD28 signaling pathways. To identify the molecular mechanisms involved in Dok-mediated inhibition, we have identified proteins that bind to the phosphotyrosine-binding (PTB) domain of Dok-1 and Dok-2. We showed that the Dok PTB domain mediates phosphotyrosine-dependent homotypic and heterotypic interactions of Dok-1 and Dok-2. Moreover, in CD2-stimulated Jurkat cells, Dok-1 coimmunoprecipitates with tyrosine-phosphorylated Dok-2. To study the involvement of PTB-mediated oligomerization in Dok function, we have generated Jurkat clones overexpressing Dok-1 or Dok-2 with a mutation that prevents oligomerization (in either the PTB domain or Tyr146 of Dok-1 and Tyr139 of Dok-2). These mutations abrogate CD2-induced phosphorylation and the ability of Dok-1 or Dok-2 to inhibit CD2-induced ERK1/2 and NFAT activation. Moreover, overexpression of Dok-1Y146F or Dok-2Y139F interferes with CD2-induced phosphorylation of endogenous Dok, whereas overexpression of PTB mutant or wild-type Dok does not. Taken together, these data indicate that PTB-mediated oligomerization of Dok-1 and Dok-2 represents an essential step for Dok phosphorylation and function.