A new derivative of vitamin C and its application to the synthesis of labelled ascorbic acid

1. The preparation of a mono-O-cyclohexylidene derivative of l-ascorbic acid is described. 2. The new compound is shielded by the cyclohexanone group at C-5 and C-6 of the ascorbic acid molecule, while the double bond between C-2 and C-3 is kept intact. 3. The double bond of the new derivative is more resistant to oxidation than its parent compound. 4. Ascorbic acid is easily regenerated by mild acid hydrolysis. 5. The new derivative facilitates the synthesis of (14)C-labelled vitamin C.     

Strain differences among mice in taste psychophysics of sucrose octaacetate

SWR/J inbred mice consistently avoided a 10^–4 M sucroseoctaacetate (SOA) solution in unconditioned two-bottle preferencetests whereas mice of all other inbred strains tested did not(confirming a previous report that used SWR mice of a differentsubline). In a conditioned taste aversion procedure SWR/J miceavoided SOA at concentrations from 10^–3 M to 10^–7M but not at 10^–8 M. Various other inbred strains firstfailed to avoid SOA at concentrations from 10^–3 M to 10^–5M. The major strain difference between SWR and other inbredmice was robust across rearing regimes and when tested withother psychophysical procedures. In single-bottle, free-lickingtests SWR/J mice differed from C57L/J mice in response to SOAfollowing extremely brief exposure to the SOA.The SOA detectionthreshold differences indicated by these psychophysical proceduresare also consistent with differences reported from electrophysiologicalrecordings from glossopharyngeal and chorda tympani nerves inmice of several of the same strains.     

Genomic and Non-genomic Actions of Progesterone in the Control of Female Hamster Sexual Behavior

Progesterone (P) in both the ventromedial hypothalamus (VMH) and the ventral tegmental area (VTA) is necessary to facilitate sexual receptivity in estrogen-primed hamsters. The mechanism of P may be different in the VMH and VTA, as there are many intracellular progestin receptors (PR) in the VMH but few in the VTA. Progesterone conjugated to bovine serum albumin (P-3-BSA) does not bind well to intracellular PR or permeate the surface of neuronal membranes. However, VTA application of P-3-BSA rapidly increases sexual receptivity if P has been applied earlier to the VMH. P-3-BSA is ineffective when applied to the VMH. The membrane-limited effect of P may be related to the ability of some progestins to modulate the GABA_A-benzodiazepine receptor complex (GBRC). We have found that infusions of a GABA_A agonist, muscimol, into the VTA enhance and a GABA_A antagonist, bicuculline, inhibit receptivity. Because P itself is not highly effective at the GBRC, and since the most potent modulators of the GBRC, the 5α-reduced progestins, do not bind well to PRs, progestin metabolites were applied to the VTA. Only the potent GBRC modulators facilitated sexual receptivity when applied to the VTA concurrent with P to the VMH. The reverse treatment, with a progestin metabolite implanted into the VMH, was ineffective. VTA infusions of an inhibitor of 5α-reductase also attenuated behavioral estrus in hamsters. These data are consistent with P facilitation of sexual receptivity being genomically mediated in the VMH, while the non-genomic actions of P in the VTA may be a result of metabolism and subsequent interaction with the GBRC.     

Generation of monoclonal antibodies to vertebrate albumins for analysis of arthropod blood meals

An immunoassay using monoclonal antibodies (MAbs) that are specific for different vertebrate taxa (from class to species) has been developed that simplifies and facilitates analysis of vertebrate blood meals from arthropod vectors. The MAbs have been prepared against the single protein albumin, the most abundant protein in vertebrate sera. A panel of these antibodies has been generated against albumins from 33 species of vertebrates, representing four classes, 15 orders, and 25 families. Immunoreactivity of albumin in mosquito blood meals can be detected as late as 48 h after feeding. Immunoassays with MAbs can be carried out in the field as well as the laboratory. Used in conjunction with nucleic acid assays or used alone with an appropriate assortment of antibodies, the assay is simple, sensitive, and unambiguous.