Avian Malaria Among House Sparrows: a Survey of Disease and Mosquito Vectors (Diptera: Culicidae) in Reed City, Michigan

Nine of 350 house sparrows caught in Reed City, Michigan, had malaria parasites detectable on Giemsa-stained thin films. All of the infected birds were juveniles, Parasitemias were too low to permit identification of the Plasmodium present. Collection of potential vector mosquitoes showed that Culex pipiens and Culex restuans were present, but in low numbers

Developing methods for strategic evaluation in agricultural research and production

We analyze instruments to evaluate investment strategies as new options for co-operatives within the wheat production chain. Using a value-based management the extension of our concept, a “cooperative balanced scorecard” is discussed as we propose the further differentiation of the scorecard’s financial perspective. This is a market development-driven approach as cooperatives may be regarded as commodity-price-intermediators for their members. Proposing this approach we use a simple model of conjoint-hedging in intermediating firms within agribusiness.Agribusiness, Wheat Production, Cooperatives, Intermediation, Value-based Management, Commodity Markets., Agricultural and Food Policy,

The effects of mismatches on hybridization in DNA microarrays: determination of nearest neighbor parameters

Quantifying interactions in DNA microarrays is of central importance for a better understanding of their functioning. Hybridization thermodynamics for nucleic acid strands in aqueous solution can be described by the so-called nearest-neighbor model, which estimates the hybridization free energy of a given sequence as a sum of dinucleotide terms. Compared with its solution counterparts, hybridization in DNA microarrays may be hindered due to the presence of a solid surface and of a high density of DNA strands. We present here a study aimed at the determination of hybridization free energies in DNA microarrays. Experiments are performed on custom Agilent slides. The solution contains a single oligonucleotide. The microarray contains spots with a perfect matching complementary sequence and other spots with one or two mismatches: in total 1006 different probe spots, each replicated 15 times per microarray. The free energy parameters are directly fitted from microarray data. The experiments demonstrate a clear correlation between hybridization free energies in the microarray and in solution. The experiments are fully consistent with the Langmuir model at low intensities, but show a clear deviation at intermediate (non-saturating) intensities. These results provide new interesting insights for the quantification of molecular interactions in DNA microarrays.Comment: 31 pages, 5 figure

Tubulization with chitosan guides for the repair of long gap peripheral nerve injury in the rat

Biosynthetic guides can be an alternative to nerve grafts for reconstructing severely injured peripheral nerves. The aim of this study was to evaluate the regenerative capability of chitosan tubes to bridge critical nerve gaps (15 mm long) in the rat sciatic nerve compared with silicone (SIL) tubes and nerve autografts (AGs). A total of 28 Wistar Hannover rats were randomly distributed into four groups (n = 7 each), in which the nerve was repaired by SIL tube, chitosan guides of low (∼2%, DAI) and medium (∼5%, DAII) degree of acetylation, and AG. Electrophysiological and algesimetry tests were performed serially along 4 months follow-up, and histomorphometric analysis was performed at the end of the study. Both groups with chitosan tubes showed similar degree of functional recovery, and similar number of myelinated nerve fibers at mid tube after 4 months of implantation. The results with chitosan tubes were significantly better compared to SIL tubes (P < 0.01), but lower than with AG (P < 0.01). In contrast to AG, in which all the rats had effective regeneration and target reinnervation, chitosan tubes from DAI and DAII achieved 43 and 57% success, respectively, whereas regeneration failed in all the animals repaired with SIL tubes. This study suggests that chitosan guides are promising conduits to construct artificial nerve grafts

2-[2-Benzoyl-3,3-bis­(methyl­sulfan­yl)prop-2-enyl­idene]malononitrile

The title compound, C15H12N2OS2, is an example of a push–pull butadiene in which the electron-releasing methyl­sulfanyl groups and electron-withdrawing nitrile groups on either end of the butadiene chain enhance the conjugation in the system. Short intra­molecular C—H⋯S inter­actions are observed. In the crystal structure, an O⋯C short contact of 2.917 (3) Å is observed

Statistical mechanics of secondary structures formed by random RNA sequences

The formation of secondary structures by a random RNA sequence is studied as a model system for the sequence-structure problem omnipresent in biopolymers. Several toy energy models are introduced to allow detailed analytical and numerical studies. First, a two-replica calculation is performed. By mapping the two-replica problem to the denaturation of a single homogeneous RNA in 6-dimensional embedding space, we show that sequence disorder is perturbatively irrelevant, i.e., an RNA molecule with weak sequence disorder is in a molten phase where many secondary structures with comparable total energy coexist. A numerical study of various models at high temperature reproduces behaviors characteristic of the molten phase. On the other hand, a scaling argument based on the extremal statistics of rare regions can be constructed to show that the low temperature phase is unstable to sequence disorder. We performed a detailed numerical study of the low temperature phase using the droplet theory as a guide, and characterized the statistics of large-scale, low-energy excitations of the secondary structures from the ground state structure. We find the excitation energy to grow very slowly (i.e., logarithmically) with the length scale of the excitation, suggesting the existence of a marginal glass phase. The transition between the low temperature glass phase and the high temperature molten phase is also characterized numerically. It is revealed by a change in the coefficient of the logarithmic excitation energy, from being disorder dominated to entropy dominated.Comment: 24 pages, 16 figure

Second Generation of Antisense Oligonucleotides: From Nuclease Resistance to Biological Efficacy in Animals

From efforts to improve the biophysical properties of antisense oligonucleotides by incorporating backbone- or sugar-modified nucleoside analogs, 2'-O-methoxyethyl ribonucleosides 8b were identified as building blocks for a second generation of antisense oligonucleotides. Compounds containing these modifications were demonstrated to combine the benefit of a high binding affinity to the RNA complement with a large increase in nuclease resistance, allowing the use of regular phosphodiester linkages. Chimeric oligonucleotides with 2'-O-methoxyethyl ribonucleosides, 8b, in the wings and a central DNA-phosphorothioate window were shown to efficiently downregulate C-'raf' kinase and PKC-α messenger-RNA in tumor cell lines resulting in a profound inhibition of cell proliferation. The same compounds were able to effectively reduce the growth of tumors in animal models at low concentrations indicating the potential utility of these second generation antisense oligonucleotides for therapeutic applications

Thermodynamic analysis of 5′ and 3′ single- and 3′ double-nucleotide overhangs neighboring wobble terminal base pairs

Thermodynamic parameters are reported for duplex formation of 40 self-complementary RNA duplexes containing wobble terminal base pairs with all possible 3′ single and double-nucleotide overhangs, mimicking the structures of short interfering RNAs (siRNA) and microRNAs (miRNA). Based on nearest neighbor analysis, the addition of a single 3′ dangling nucleotide increases the stability of duplex formation up to 1 kcal/mol in a sequence-dependent manner. The addition of a second dangling nucleotide increases the stability of duplexes closed with wobble base pairs in an idiosyncratic manner. The results allow for the development of a nearest neighbor model, which improves the predication of free energy and melting temperature for duplexes closed by wobble base pairs with 3′ single or double-nucleotide overhangs. Phylogenetic analysis of naturally occurring miRNAs was performed. Selection of the effector miR strand of the mature miRNA duplex appears to be dependent on the orientation of the GU closing base pair rather than the identity of the 3′ double-nucleotide overhang. Thermodynamic parameters for the 5′ single terminal overhangs adjacent to wobble closing base pairs are also presented