Long-term memory modules

One particular kind of structure offers possible explanations, for long-term memory, efficient consolidation of stored information from the environment, clustering of data strings and multimodal functioning. It is a possible model for pieces of neural structure and its use offers a uniform method for both studying and constructing an extensive class of mechanisms.     

Allium cepa L. Cultivars from Four Continents Compared by Flow Cytometry show Nuclear DNA Constancy

In 1965 Van't Hof estimated the nuclear DNA amount of an unidentifiedAllium cepa L. cultivar as 2C = 33.55 pg (Experimental CellResearch39: 8–58). This value has been adopted by commonusage as the main calibration standard for angiosperm DNA C-valueestimations. However, different cultivars have been used whileassuming species DNA C-value constancy. Surprisingly this assumptionhas never been tested. A. cepa is an outbreeder with telomericheterochromatic segments, so intraspecific variation in C-value,possibly correlated with environmental factors as seen in Zeamays L., might be expected. We used laser flow cytometry tocompare nuclear DNA amounts in roots of six A. cepa cultivarsused as calibration standards or from different environments.Tissues from one cultivar, or similar volumes of tissue fromtwo cultivars, were run and the variance between nuclei in 2Cpeaks compared. Only one shoulderless 2C peak was seen for allpairs of co-chopped cultivars. Thus, no large differences inC-value between cultivars from different environments were found.Moreover, comparing cultivars run singly or as pairs showedno evidence for increased variation in 2C peaks in the latter,and hence of critical differences in DNA amounts between ‘AilsaCraig’ and another cultivar. Such variation was insufficientto make their use as alternative calibration standards, or thepractice of imputing Van't Hof's original C-value estimate tothem, unacceptable for most practical purposes. Given the mechanismsknown which can generate genome size variation, the degree ofconstancy in DNA C-value found seems remarkable. Copyright 2000Annals of Botany Company Allium cepa, onion cultivars, calibration standards, DNA C-value constancy, flow cytometry     

1-Alkyl-3-amino-5-aryl-1H-[1,2,4]triazoles: novel synthesis via cyclization of N-acyl-S-methylisothioureas with alkylhydrazines and their potent corticotropin-releasing factor-1 (CRF(1)) receptor antagonist activities.

Cyclizations of alkylhydrazines with N-acyl-S-methylisothioureas, readily synthesized from acyl chlorides, sodium thioisocyanate, dialkylamines then methyl iodide in a one-pot reaction, gave 1-alkyl-3-dialkylamino-5-phenyltriazoles 7 as major products. The regioisomers were assigned through the use of NOE NMR experiments. While bearing a N-bis(cyclopropyl)methyl-N-propylamino group, this series of compounds shows very good binding affinity on the human CRF₁ receptor. Among them, 1-methyl-3-[N-bis(cyclopropyl)methyl-N-propylamino]-5-(2,4-dichlorophenyl)-1H-[1,2,4]triazole 7a had the best binding affinity for the CRF₁ receptor (K_i=9 nM).     

Inhibition of Neuronal Degenerin/Epithelial Na+ Channels by the Multiple Sclerosis Drug 4-Aminopyridine

The voltage-gated K⁺ (Kv) channel blocker 4-aminopyridine (4-AP) is used to target symptoms of the neuroinflammatory disease multiple sclerosis (MS). By blocking Kv channels, 4-AP facilitates action potential conduction and neurotransmitter release in presynaptic neurons, lessening the effects of demyelination. Because they conduct inward Na⁺ and Ca²⁺ currents that contribute to axonal degeneration in response to inflammatory conditions, acid-sensing ion channels (ASICs) contribute to the pathology of MS. Consequently, ASICs are emerging as disease-modifying targets in MS. Surprisingly, as first demonstrated here, 4-AP inhibits neuronal degenerin/epithelial Na⁺ (Deg/ENaC) channels, including ASIC and BLINaC. This effect is specific for 4-AP compared with its heterocyclic base, pyridine, and the related derivative, 4-methylpyridine; and akin to the actions of 4-AP on the structurally unrelated Kv channels, dose- and voltage-dependent. 4-AP has differential actions on distinct ASICs, strongly inhibiting ASIC1a channels expressed in central neurons but being without effect on ASIC3, which is enriched in peripheral sensory neurons. The voltage dependence of the 4-AP block and the single binding site for this inhibitor are consistent with 4-AP binding in the pore of Deg/ENaC channels as it does Kv channels, suggesting a similar mechanism of inhibition in these two classes of channels. These findings argue that effects on both Kv and Deg/ENaC channels should be considered when evaluating the actions of 4-AP. Importantly, the current results are consistent with 4-AP influencing the symptoms of MS as well as the course of the disease because of inhibitory actions on Kv and ASIC channels, respectively.     

Defoliation-induced enhancement of total aboveground nitrogen yield of grasses

We conducted an experiment in a northern mixed-grass prairie at Wind Cave National Park, South Dakota, USA to evaluate the effect of defoliation frequency on aboveground net primary production (ANPP), shoot nitrogen concentration, and aboveground N yield of graminoids. ANPP was significantly reduced at weekly and biweekly defoliation frequencies, but unaffected relative to unclipped controls at monthly and bimonthly frequencies. By contrast, clipping at all frequencies increased shoot N concentration above that of controls, and this increase was greatest at monthly or more frequent defoliations. Total aboveground N yield and potential N yield to grazers were greatest at intermediate (bimonthly to biweekly) frequencies. We suggest that grazers may maximize their nutritional status in this system by periodically regrazing areas at frequencies near the approximately monthly optimum that we observed.     

Towards resolving and redefining Amphipyrinae (Lepidoptera,Noctuoidea, Noctuidae): a massively polyphyletic taxon

Amphipyrinae have long been a catchall taxon for Noctuidae, with most members lacking discernible morphological synapomorphies that would allow their assignment to one of the many readily diagnosable noctuid subfamilies. Here data from seven gene regions (> 5500 bp) for more than 120 noctuid genera are used to infer a phylogeny for Amphipyrinae and related subfamilies. Sequence data for 57 amphipyrine genera – most represented by the type species of the genus – are examined. We present here the first large‐scale molecular phylogenetic study of Amphipyrinae and the largest molecular phylogeny of Noctuidae to date; several proposed nomenclatural changes for well‐supported results; and the identification of areas of noctuid phylogeny where greater taxon sampling and/or genomic‐scale data are needed. Adult and larval morphology, along with life‐history traits, for taxonomic groupings most relevant to the results are discussed. Amphipyrinae are significantly redefined; many former amphipyrines, excluded as a result of these analyses, are reassigned to other noctuid subfamily‐level taxa. Four genera, Chamaeclea Grote, Heminocloa Barnes & Benjamin, Hemioslaria Barnes & Benjamin and Thurberiphaga Dyar, are transferred to the tribe Chamaecleini Keegan & Wagner tribe n. in Acontiinae. Stiriina is elevated to Stiriinae rev. stat. , Grotellina is elevated to Grotellinae rev. stat. and Annaphilina is elevated to Annaphilini rev. stat. Acopa Harvey is transferred to Bryophilinae, Aleptina Dyar is transferred to Condicinae, Leucocnemis Hampson and Oxycnemis gracillinea (Grote) are transferred to Oncocnemidinae, Nacopa Barnes & Benjamin is transferred to Noctuinae and Narthecophora Smith is transferred to Stiriinae. Azenia Grote (and its subtribe Azeniina), Cropia Walker, Metaponpneumata Möschler, Sexserrata Barnes & Benjamin and Tristyla Smith are transferred to Noctuidae incertae sedis. Hemigrotella Barnes & McDunnough (formerly in subtribe Grotellina) is retained in Amphipyrinae. Argentostiria Poole and Bistica Dyar are retained in Stiriini but removed from incertae sedis position. This published work has been registered on ZooBank: http://zoobank.org/urn:lsid:zoobank.org:pub:4A140782‐31BA‐445A‐B7BA‐6EAB98ED43FA .     

Use of Radiation Hybrid panels to map genetic loci

The mapping of genetic loci within organisms has been accelerated by the advent of Radiation Hybrid (RH) panels. These panels are available for humans and non-humans including mice, baboon, rat, and canine. This article contains a general protocol for the use of the Genebridge 4 whole genome RH panel to map a human locus. This protocol may also be adjusted to suit the other RH panels currently available.