Clustering, haplotype diversity and locations of MIC-3: a unique root-specific defense-related gene family in Upland cotton (Gossypium hirsutum L.)

MIC-3 is a recently identified gene family shown to exhibit increased root-specific expression following nematode infection of cotton plants that are resistant to root-knot nematode. Here, we cloned and sequenced MIC-3 genes from selected diploid and tetraploid cotton species to reveal sequence differences at the molecular level and identify chromosomal locations of MIC-3 genes in Gossypium species. Detailed sequence analysis and phylogenetic clustering of MIC-3 genes indicated the presence of multiple MIC-3 gene members in Gossypium species. Haplotypes of a MIC-3 gene family member were discovered by comparative analysis among consensus sequences across genotypes within an individual clade in the phylogram to overcome the problem of duplicated loci in the tetraploid cotton. Deficiency tests of the SNPs delimited six A_t-genome members of the MIC-3 family clustered to chromosome arm 4sh, and one D_t-genome member to chromosome 19. Clustering was confirmed by long-PCR amplification of the intergenic regions using A_t-genome-specific MIC-3 primer pairs. The clustered distribution may have been favored by selection for responsiveness to evolving disease and/or pest pressures, because large variants of the MIC-3 gene family may have been recovered from small physical areas by recombination. This could give a buffer against selection pressure from a broad range of pest and pathogens in the future. To our knowledge, these are the first results on the evolution of clustering and genome-specific haplotype members of a unique cotton gene family associated with resistant response against a major pathogen.     

Evidence for species differences in the pattern of androgen receptor distribution in relation to species differences in an androgen‐dependent behavior

Chickens (Gallus gallus domesticus) and Japanese quail (Coturnix japonica), two closely related gallinaceous bird species, exhibit a form of vocalization—crowing—which differs between the species in two components: its temporal acoustic pattern and its accompanying postural motor pattern. Previous work utilizing the quail‐chick chimera technique demonstrated that the species‐specific characteristics of the two crow components are determined by distinct brain structures: the midbrain confers the acoustic pattern, and the caudal hindbrain confers the postural pattern. Crowing is induced by androgens, acting directly on androgen receptors. As a strategy for identifying candidate neurons in the midbrain and caudal hindbrain that could be involved in crow production, we performed immunocytochemistry for androgen receptors in these brain regions in both species. We also investigated midbrain‐to‐hindbrain vocal‐motor projections. In the midbrain, both species showed prominent androgen receptor immunoreactivity in the nucleus intercollicularis, as had been reported in previous studies. In the caudal hindbrain, we discovered characteristic species differences in the pattern of androgen receptor distribution. Chickens, but not quail, showed strong immunoreactivity in the tracheosyringeal division of the hypoglossal nucleus, whereas quail, but not chickens, possessed strong immunoreactivity in a region of the ventrolateral medulla. Some of these differences in hindbrain androgen receptor distribution may be related to the species differences in the postural component of crowing behavior. The results of the present study imply that the spatial distribution of receptor proteins can vary even between closely related species. Such variation in receptor distribution could underlie the evolution of species differences in behavior. © 2002 Wiley Periodicals, Inc. J Neurobiol 52: 203–220, 2002     

The intD mobile genetic element from Dichelobacter nodosus, the causative agent of ovine footrot, is associated with the benign phenotype

The Gram-negative anaerobic pathogen Dichelobacter nodosus is the principal causative agent of footrot in sheep. The intA, intB and intC elements are mobile genetic elements which integrate into two tRNA genes downstream from csrA (formerly glpA) and pnpA in the D. nodosus chromosome. CsrA homologues act as global repressors of virulence in several bacterial pathogens, as does polynucleotide phosphorylase, the product of pnpA. We have proposed a model in which virulence in D. nodosus is controlled in part by the integration of genetic elements downstream from csrA and pnpA, altering the expression of these putative global regulators of virulence. We describe here a novel integrated genetic element, the intD element, which is 32 kb in size and contains an integrase gene, intD, several genes related to genes on other integrated elements of D. nodosus, a type IV secretion system and a putative mobilisation region, suggesting that the intD element has a role in the transfer of other genetic elements. Most of the D. nodosus strains examined which contained the intD gene were benign, with intD integrated next to pnpA, supporting our previous observation that virulent strains of D. nodosus have the intA element next to pnpA.     

Nanoparticle-Delivered Multimeric Soluble CD40L DNA Combined with Toll-Like Receptor Agonists as a Treatment for Melanoma

Stimulation of CD40 or Toll-Like Receptors (TLR) has potential for tumor immunotherapy. Combinations of CD40 and TLR stimulation can be synergistic, resulting in even stronger dendritic cell (DC) and CD8+ T cell responses. To evaluate such combinations, established B16F10 melanoma tumors were injected every other day X 5 with plasmid DNA encoding a multimeric, soluble form of CD40L (pSP-D-CD40L) either alone or combined with an agonist for TLR1/2 (Pam₃CSK₄ ), TLR2/6 (FSL-1 and MALP2), TLR3 (polyinosinic-polycytidylic acid, poly(I:C)), TLR4 ( monophosphoryl lipid A, MPL), TLR7 (imiquimod), or TLR9 (Class B CpG phosphorothioate oligodeoxynucleotide, CpG). When used by itself, pSP-D-CD40L slowed tumor growth and prolonged survival, but did not lead to cure. Of the TLR agonists, CpG and poly(I:C) also slowed tumor growth, and the combination of these two TLR agonists was more effective than either agent alone. The triple combination of intratumoral pSP-D-CD40L + CpG + poly(I:C) markedly slowed tumor growth and prolonged survival. This treatment was associated with a reduction in intratumoral CD11c+ dendritic cells and an influx of CD8+ T cells. Since intratumoral injection of plasmid DNA does not lead to efficient transgene expression, pSP-D-CD40L was also tested with cationic polymers that form DNA-containing nanoparticles which lead to enhanced intratumoral gene expression. Intratumoral injections of pSP-D-CD40L-containing nanoparticles formed from polyethylenimine (PEI) or C32 (a novel biodegradable poly(B-amino esters) polymer) in combination with CpG + poly(I:C) had dramatic antitumor effects and frequently cured mice of B16F10 tumors. These data confirm and extend previous reports that CD40 and TLR agonists are synergistic and demonstrate that this combination of immunostimulants can significantly suppress tumor growth in mice. In addition, the enhanced effectiveness of nanoparticle formulations of DNA encoding immunostimulatory molecules such as multimeric, soluble CD40L supports the further study of this technology for tumor immunotherapy.     

Strategies for signal amplification in nucleic acid detection

Many aspects of molecular genetics necessitate the detection of nucleic acid sequences. Current approaches involving target amplification (in situ PCR, Primed in situ Labeling, Self-Sustained Sequence Replication, Strand Displacement Amplification), probe amplification (Ligase Chain Reaction, Padlock Probes, Rolling Circle Amplification) and signal amplification (Tyramide Signal Amplification, Branched DNA Amplification) are summarized in the present review, together with their advantages and limitations.