Ionotropic glutamate receptor AMPA 1 is associated with ovulation rate

Ionotropic glutamate receptors mediate most excitatory neurotransmission in the central nervous system by opening ion channels upon the binding of glutamate. Despite the essential roles of glutamate in the control of reproduction and anterior pituitary hormone secretion, there is a limited understanding of how glutamate receptors control ovulation. Here we reveal the function of the ionotropic glutamate receptor AMPA-1 (GRIA1) in ovulation. Based on a genome-wide association study in Bos taurus, we found that ovulation rate is influenced by a variation in the N-terminal leucine/isoleucine/valine-binding protein (LIVBP) domain of GRIA1, in which serine is replaced by asparagine. GRIA1(Asn) has a weaker affinity to glutamate than GRIA1(Ser), both in Xenopus oocytes and in the membrane fraction of bovine brain. This single amino acid substitution leads to the decreased release of gonadotropin-releasing hormone (GnRH) in immortalized hypothalamic GT1-7 cells. Cows with GRIA1(Asn) have a slower luteinizing hormone (LH) surge than cows with GRIA1(Ser). In addition, cows with GRIA1(Asn) possess fewer immature ovarian follicles before superovulation and have a lower response to hormone treatment than cows with GRIA1(Ser). Our work identified that GRIA1 is a critical mediator of ovulation and that GRIA1 might be a useful target for reproductive therapy.     

Does conditioned taste aversion learning in the pond snail Lymnaea stagnalis produce conditioned fear?

In conditioned taste aversion (CTA) training performed on the pond snail Lymnaea stagnalis, a stimulus (the conditional stimulus, CS; e.g., sucrose) that elicits a feeding response is paired with an aversive stimulus (the unconditional stimulus, US) that elicits the whole-body withdrawal response and inhibits feeding. After CTA training and memory formation, the CS no longer elicits feeding. We hypothesize that one reason for this result is that after CTA training the CS now elicits a fear response. Consistent with this hypothesis, we predict the CS will cause (1) the heart to skip a beat and (2) a significant change in the heart rate. Such changes are seen in mammalian preparations exposed to fearful stimuli. We found that in snails exhibiting long-term memory for one-trial CTA (i.e., good learners) the CS significantly increased the probability of a skipped heartbeat, but did not significantly change the heart rate. The probability of a skipped heartbeat was unaltered in control snails given backward conditioning (US followed by CS) or in snails that did not acquire associative learning (i.e., poor learners) after the one-trial CTA training. These results suggest that as a consequence of acquiring CTA, the CS evokes conditioned fear in the conditioned snails, as evidenced by a change in the nervous system control of cardiac activity.     

Regulation of the expression of lysyl oxidase mRNA in cultured rabbit retinal pigment epithelium cells.

Lysyl oxidase, an extracellular amine oxidase, controls the maturation of collagen and elastin. We examined the regulation of lysyl oxidase mRNA in cultured rabbit retinal pigment epithelium (RPE) cells in relation to the changes in subretinal fluid transport and phenotype of RPE cells. The level of the mRNA in cells grown on microporous membranes was markedly increased by application of hyperosmotic mannitol solution on the apical side (191% of control), implying that RPE cells express more lysyl oxidase in the condition which may cause the accumulation of subretinal fluid. Platelet-derived growth factor increased the mRNA level in subconfluent cells in culture (137% of control) and basic fibroblast growth factor decreased it (79% of control). In addition, exposure of cells to retinoic acid alone or in combination with dibutyryl cAMP for 22 days markedly decreased the level of lysyl oxidase mRNA (52 or 35% of control) while increasing the level of mRNA of N-acetylglucosaminidase (NAG), a marker enzyme for lysosomes (162 or 142% of control). Moreover, the level of lysyl oxidase mRNA in cells grown on microporous membranes was lower than that in cells grown on plastic dishes, while the level of NAG mRNA in the former cells was higher than that in the latter. Taken together, the expression of lysyl oxidase seemed to increase during proliferation of RPE cells and decrease toward differentiation. beta-Aminopropionitrile, an inhibitor of lysyl oxidase, significantly inhibited the contraction of collagen gels by fetal calf serum, suggesting that lysyl oxidase may be involved in pathogenesis caused by RPE cells.     

Endogenous neurotoxic dopamine derivative covalently binds to Parkinson's disease‐associated ubiquitin C‐terminal hydrolase L1 and alters its structure and function

Parkinson's disease (PD) is a common neurodegenerative disease, but its pathogenesis remains elusive. A mutation in ubiquitin C‐terminal hydrolase L1 (UCH‐L1) is responsible for a form of genetic PD which strongly resembles the idiopathic PD. We previously showed that 1‐(3′,4′‐dihydroxybenzyl)‐1,2,3,4‐tetrahydroisoquinoline (3′,4′DHBnTIQ) is an endogenous parkinsonism‐inducing dopamine derivative. Here, we investigated the interaction between 3′,4′DHBnTIQ and UCH‐L1 and its possible role in the pathogenesis of idiopathic PD. Our results indicate that 3′,4′DHBnTIQ binds to UCH‐L1 specifically at Cys152 in vitro. In addition, 3′,4′DHBnTIQ treatment increased the amount of UCH‐L1 in the insoluble fraction of SH‐SY5Y cells and inhibited its hydrolase activity to 60%, reducing the level of ubiquitin in the soluble fraction of SH‐SY5Y cells. Catechol‐modified UCH‐L1 as well as insoluble UCH‐L1 were detected in the midbrain of 1‐methyl‐4‐phenyl‐1,2,3,6‐tetrahydropyridine‐treated PD model mice. Structurally as well as functionally altered UCH‐L1 have been detected in the brains of patients with idiopathic PD. We suggest that conjugation of UCH‐L1 by neurotoxic endogenous compounds such as 3′,4′DHBnTIQ might play a key role in onset and progression of idiopathic PD.

     

Serological Surveillance Development for Tropical Infectious Diseases Using Simultaneous Microsphere-Based Multiplex Assays and Finite Mixture Models

Background

A strategy to combat infectious diseases, including neglected tropical diseases (NTDs), will depend on the development of reliable epidemiological surveillance methods. To establish a simple and practical seroprevalence detection system, we developed a microsphere-based multiplex immunoassay system and evaluated utility using samples obtained in Kenya.

Methods

We developed a microsphere-based immuno-assay system to simultaneously measure the individual levels of plasma antibody (IgG) against 8 antigens derived from 6 pathogens: Entamoeba histolytica (C-IgL), Leishmania donovani (KRP42), Toxoplasma gondii (SAG1), Wuchereria bancrofti (SXP1), HIV (gag, gp120 and gp41), and Vibrio cholerae (cholera toxin). The assay system was validated using appropriate control samples. The assay system was applied for 3411 blood samples collected from the general population randomly selected from two health and demographic surveillance system (HDSS) cohorts in the coastal and western regions of Kenya. The immunoassay values distribution for each antigen was mathematically defined by a finite mixture model, and cut-off values were optimized.

Findings

Sensitivities and specificities for each antigen ranged between 71 and 100%. Seroprevalences for each pathogen from the Kwale and Mbita HDSS sites (respectively) were as follows: HIV, 3.0% and 20.1%; L. donovani, 12.6% and 17.3%; E. histolytica, 12.8% and 16.6%; and T. gondii, 30.9% and 28.2%. Seroprevalences of W. bancrofti and V. cholerae showed relatively high figures, especially among children. The results might be affected by immunological cross reactions between W. bancrofti-SXP1 and other parasitic infections; and cholera toxin and the enterotoxigenic E. coli (ETEC), respectively.

Interpretation

A microsphere-based multi-serological assay system can provide an opportunity to comprehensively grasp epidemiological features for NTDs. By adding pathogens and antigens of interest, optimized made-to-order high-quality programs can be established to utilize limited resources to effectively control NTDs in Africa.     

Evidence for detection of rat P2X4 receptor expressed on cells by generating monoclonal antibodies recognizing the native structure

Purinergic Signalling - P2X purinergic receptors are ATP-driven ionic channels expressed as trimers and showing various functions. A subtype, the P2X4 receptor present on microglial cells is highly...     

Direct and feeding‐induced interactions between two rice planthoppers, Sogatella furcifera and Nilaparvata lugens: effects on dispersal capability and performance

Abstract. 1. A series of laboratory experiments was conducted to explore the effects of inter‐specific interactions, both direct interactive effects and those induced through previous feeding, on the dispersal capability (proportion of macropterous adults) and performance (development time and survival) of two wing‐dimorphic planthoppers, the whitebacked planthopper Sogatella furcifera and the brown planthopper Nilaparvata lugens, two pests of rice throughout Asia. 2. An asymmetric effect of inter‐specific crowding on dispersal capability was detected between the two planthoppers. With density controlled, the proportion of macropterous adults in N. lugens was higher when raised in mixed populations with S. furcifera than in pure cultures comprised of conspecifics, suggesting that interspecific effects on dispersal capability are stronger than intraspecific effects. In contrast, interspecific effects on macroptery (%) were weaker than intraspecific impacts for S. furcifera. 3. This trend was parallelled by adverse competitive effects on survival, with interspecific effects stronger than intraspecific impacts for N. lugens and intraspecific effects stronger for S. furcifera. 4. Crowding also affected the incidence of macroptery indirectly through feeding‐induced changes in plant physiology. Rearing N. lugens on plants fed on previously by heterospecifics resulted in a higher incidence of macroptery in females and protracted development than for N. lugens raised on plants fed on previously by conspecifics. By contrast, the intraspecific effect of previous feeding was stronger than the interspecific effect in S. furcifera, with higher macropter production and prolonged development occurring on plants exposed previously to conspecifics. 5. The results suggest that interspecific interactions between herbivorous insects, both direct and via feeding‐induced changes in plant physiology, can have negative consequences for performance and survival and promote the production of flight‐capable adults that can disperse.