James A. Bixby

Polymorphic Forms of Expressed Bovine Interferon-τ Genes: Relative Transcript Abundance during Early Placental Development, Promoter Sequences of Genes and Biological Activity of Protein Products1

Multiple interferon (IFN)-τ genes exist in cattle, but it has remained unclear how many are expressed, the extent of their variation, and whether different genes exhibit similar patterns of expression and code for proteins with similar biological activities. A total of 118 complementary DNA (cDNA) were bi-directionally sequenced from reverse-transcribed bovine (bo) conceptus RNA over the period from blastocyst formation until day 25 of pregnancy. Fourteen different cDNAs, encoding eight different IFN-τ, were confirmed unique. All showed high sequence conservation (>98% nucleotide identity; >96% amino acid identity). The cDNA fell into three, recently evolved, phylogenetic groups (τ1, 2, and 3). Mean concentrations of IFN-τ messenger RNA were greater at day 17 and day 19 than at day 14 and day 25, with different genes showing comparable expression patterns, although there appeared to be a major bias in expression of two genes (for boIFN-τ1c and τ3a) in blastocysts. Genes representing members of the three b...

A Classification for the Interferon-τ

An attempt has been made to provide a rational organization for the many interferon-τ (IFN-τ) sequences entered in GenBank based on phylogenetic analysis and common amino acid substitutions, which might form the basis for a universal nomenclature scheme. Over the 13 years since these genes were first discovered, large numbers of cDNA and gene sequences have been reported, and there is reason to suspect that representatives of all the major ovine and bovine forms have now been described. The data are consistent with the presence of many genes and also allelic variants in sheep and cattle analogous to what has been observed for the IFN-α in the human. Future variants should be easily accommodated into the scheme outlined here. A flexible system of nomenclature, based on that used for HuIFN, is needed to provide a common base for comparison between research done in different laboratories and to assign relative biologic potencies to these molecules.

A type I ovine interferon with limited similarity to IFN-α, IFN-ω and IFN-τ: gene structure, biological properties and unusual species specificity

Abstract A gene encoding a 195 amino-acid (a.a.) polypeptide with a putative 23 a.a. signal sequence that had about 60% a.a. sequence identity to ovine interferon-ω (OvIFN-ω) and 55% or less identity to BoIFN-τ, OvIFN-τ and all known IFN-α and -β has been identified from an ovine genomic DNA library. Surprisingly, it shared almost complete identity to genes for rabbit IFN-ω within its coding sequence and proximal promoter region, although the two were different in their 3′-ends. This IFN (tentatively termed ovine IFN-ω variant, OvIFN-ωv), purified in recombinant form from E. coli, had normal antiviral activity when tested on sheep fetal tongue and brain cells and rabbit kidney cells, but very low activity towards bovine, goat and human cells. It competed with 125I-labeled BiIFN-τ for binding to IFN receptors on ovine cells. Expression of OvIFN-ω v was not detected by reverse transcription-PCR either in ovine peripheral blood leukocytes infected with Sendai virus, or in any other tissues examined. OvIFN-ω v may represent a previously unrecognized, non-virally inducible type I subtype distinct from IFN-α, -β, -ω and -τ. The presence of a conserved gene in rabbit and sheep could reflect a recent interspecies transfer.

Ribonuclease activity during induction of cold hardiness in mimosa epicotyl and hypocotyl tissues

Abstract Ribonuclease activities in both epicotyl and hypocotyl tissues of Albizzia julibrissin seedlings decreased during induction of cold hardiness. Small decreases in fresh weights during induction of cold hardiness suggest a possible relationship between RNase activities and desiccation. Relative to increases in total protein during induction of cold hardiness, decreases in RNase activities suggest some degree of specificity, possibly invloved in regulation of RNAs and protein synthesis during induction of cold hardiness.

Xylem pressure potential and chlorophyll fluorescence as indicators of freezing survival in black locust and Western hemlock seedlings

Abstract Xylem pressure potential was determined using the Scholander pressure chamber on stems of cold hardened and non-hardened black locust ( Robinia pseudoacacia L.) seedlings following freezing to various nonlethal and lethal temperatures and subsequent thawing. Correlation was found between immediate xylem pressure potential and long-term seedling survival. Chlorophyll fluorescence transients were monitored using needles of western hemlock ( Tsuga heterophylla (Raf.) Sarg.) seedlings following freezing to various non-lethal and lethal temperatures and subsequent thawing. Immediate and repeatable differences in fluorescence transients correlated with long-term seedling survival. Methodology is described and correlations discussed relative to using either chlorophyll fluorescence or xylem pressure potential as an immediate indicator of long-term freezing survival in woody plant seedlings.