Effects of 25-hydroxycholecalciferol with two D3 vitamin levels on production and immunity parameters in broiler chickens.

This study was performed in Ross 308 chickens aged 1-21 days and aimed to evaluate whether the addition of 25-hydroxycholecalciferol (25(OH)D3 ) to broiler chicken diets affects their growth performance and immunity. A completely random 2 × 2 factorial arrangement was used with two levels of vitamin D3 and the absence or presence of 25(OH)D3 , corresponding to four treatments based on sorghum + soya bean diets: (i) 200 IU of vitamin D3 /kg of feed (Diet 1) (NRC, ), (ii) Diet 1 + 69 µg of 25(OH)D3 /kg of feed (Diet 2), (iii) 5,000 IU of vitamin D3 /kg of feed (Diet 3) and (iv) Diet 3 + 69 µg of 25(OH)D3 /kg of feed (Diet 4). Each treatment was conducted with six replicates of 10 chickens each. Water and feed was supplied ad libitum. The results showed significantly increased growth and tibia ash (p < .05) in the birds fed 5,000, IU of vitamin D3 /kg + 25(OH)D3 . Additionally, the cellular immune response increased significantly (p < .05) in both treatments with added 25(OH)D3. Based on the results obtained under the current test conditions, the addition of 25(OH)D3 at a rate of 69 µg/kg to diets containing vitamin D3 improved the cellular immune response and mineral deposition in the bones of broilers aged 1-21 days. Because these parameters are very important in modern poultry farming, these results indicate that supplementation with 25(OH)D3 should improve broiler production.

Characterizing a rat Brca2 knockout model.

Evidence exists that BRCA2 carriers may have an elevated risk of breast, ovarian, colon, prostate, and pancreatic cancer. In general, carriers are defined as individuals with protein truncating mutations within the BRCA2 gene. Many Brca2 knockout lines have been produced and characterized in the mouse. We previously produced a rat Brca2 knockout strain in which there is a nonsense mutation in exon 11 between BRC repeats 2 and 3, and a truncated protein is produced. Interestingly, while such a mutation in homozygous mice would lead to limited survival of approximately 3 months, the Brca2-/- rats are 100% viable and the vast majority live to over 1 year of age. Brca2-/- rats show a phenotype of growth inhibition and sterility in both sexes. Aspermatogenesis in the Brca2-/- rats is due to a failure of homologous chromosome synapsis. Long-term phenotypes include underdeveloped mammary glands, cataract formation and lifespan shortening due to the development of tumors and cancers in multiple organs. The establishment of the rat Brca2 knockout model provides a means to study the role of Brca2 in increasing cancer susceptibility and inducing a novel ocular phenotype not previously associated with this gene.

Phomalairdenone: a new host-selective phytotoxin from a virulent type of the blackleg fungus Phoma lingam.

The chemical structure and bioactivity of phomalairdenone (7), a new sesquiterpenic host-selective phytotoxin produced by an unusual virulent type isolate of the blackleg fungus [Phoma lingam, perfect stage Leptosphaeria maculans (Desm.) Ces. et de Not.] are reported.

Histochemical localization of reverse transcriptase in polytene chromosomes of chironomids.

The localization of a reverse transcriptase-related protein in salivary gland polytene chromosomes was investigated by immunohistochemistry in two species of Chironomus. The antibodies used were raised against a recombinant protein containing phylogenetically conserved motifs of reverse transcriptases and derived from an abundant non-LTR element previously identified in Chironomus. Immunoreactive protein was found in some telomeres, in a centromeric region, in a few interstitial bands and in Balbiani ring 3. The telomeric signal was probably dependent on transcription and increased dramatically when telomeric heat shock puffs were induced. A correlation with transcription was also seen in Balbiani ring 3, the immunobinding of which disappeared after inhibition of transcription with actinomycin D.

Interspersed DNA element restricted to a specific group of telomeres in the dipteran Chironomus pallidivittatus.

Telomeres in the dipteran Chironomus pallidivittatus terminate with 340bp tandem DNA repeats belonging to different subfamilies with characteristic intertelomeric distribution. We have now found, interspersed between such repeats, a composite element of approx. 1400bp present in two similar size variants, with several components of nontelomeric origin. There were about 50 copies of the element, predominantly or exclusively present in a previously defined group of telomeres, characterized by a unique set of telomeric tandem repeat subfamilies. Elements were integrated at irregular distances from each other, and intervening telomeric tandem repeat DNA was variable in composition. Nevertheless, the flanks immediately surrounding the elements were identical for different elements; in other words, there was a site-specific insertion. We suggest that this selective invasion of a small part of the genome by an interspersed, probably rapidly evolving element is best explained by repeated gene conversions.

Interspersed centromeric element with a CENP-B box-like motif in Chironomus pallidivittatus.

Short mobile elements are present in different recombined forms as interspersed GC-rich islands between AT rich centromeric 155 bp tandem repeats in the dipteran Chironomus pallidivittatus . The basic element is 80 bp long, has a pronounced invert repeat structure and contains a 17 bp segment similar to the CENP-B box in mammals. The element inserts into a specific site of the 155 bp repeat in a defined orientation surrounded by 2 bp direct repeats. The total number per genome of the main variant is <20. Elements can be present in all centromeres from C.pallidivittatus and the sibling species Chironomus tentans with pronounced differences in distribution within and between species.

Telomeres terminating with long complex tandem repeats.

Telomeres of most investigated species terminate with short repeats and are elongated by telomerase. Short repeats have never been detected in dipteran species which have found other solutions to end a chromosome. Whereas in Drosophila melanogaster retroelements are added onto the termini, chironomids have long complex repeats at their chromosome ends. We review evidence that these units are terminal and probably have evolved from short telomeric repeats. In Chironomus pallidivittatus the units have been shown to belong to different subfamilies which have specific inter- and intrachromosomal distribution, the most terminal subfamily of repeats being characterized by pronounced secondary structures for the single strand. The complex repeats are efficiently homogenized both within and between different chromosome ends. Gene conversion is probably an important component in the coordinate evolution of the repeats but it is not known whether it is used for net synthesis of DNA. RNA is used as an intermediate in telomere elongation both by organisms having chromosomes terminating with short repeats and by D. melanogaster. It is therefore interesting that the terminal repeats in chironomids are transcribed.

Terminal long tandem repeats in chromosomes form Chironomus pallidivittatus.

We provide evidence that a chromosome end in the dipteran Chironomus pallidivittatus contains 340-bp tandem repeats reaching the extreme terminus of the chromosome. After adding synthetic oligonucleotide tails to DNA extracted from the microdissected right end of the fourth chromosome, we could demonstrate that the blocks of repeats were tailed at only one end, the chromosome terminus, the interior of the arrays being unavailable for tailing. Using PCR, we furthermore showed that the added tails were connected to 340-bp repeat DNA directly, i.e., without intervening DNA of any other kind. The tailed repeats belong to a subfamily previously known to be the most peripheral one of the different types of 340-bp units. Using plasmid controls, we could also make certain that we did not amplify rare or nonrepresentative DNA termini.

A family of complex tandem DNA repeats in the telomeres of Chironomus pallidivittatus.

A family of 340-bp tandem telomere-associated DNA repeats is present in 50- to 200-kb blocks in seven of the eight paired chromosome ends in Chironomus pallidivittatus. It consists of four main subfamilies, differing from each other by small clusters of mutations. This differentiation may reflect different functional roles for the repeats. Here we find that one subfamily, D3, is consistently localized most peripherally and extends close to the ends of the chromosomes, as shown by its sensitivity to the exonuclease Bal 31. The amounts of D3 are highly variable between individuals. The repeat characteristic for D3 forms a segment with pronounced dyad symmetry, which in single-strand form would give rise to a hairpin. Evidence from an interspecies comparison suggests that a similar structure is the result of selective forces. Another subfamily, M1, is present more proximally in a subgroup of telomeres characterized by a special kind of repeat variability. Thus, a complex block with three kinds of subfamilies may occupy different M1 telomeres depending on the stock of animals. We conclude that subfamilies are differentially distributed between and within telomeres and are likely to serve different functions.

Use of electrocardiographic analysis for investigation of ascites syndrome in broiler chickens.

This study was conducted (at high altitude [1969 meters]) to determine whether chicks predisposed to cardiac failure and ascites could be identified and followed during growout with non-invasive electrocardiographic (ECG) techniques. ECG recordings were made on 40 chicks at 1 week of age. All recordings were analyzed by quantifying the amplitude in millivolts of the R-, S-, and T-waves in each of the recordings. During the study, ascites-related mortality was 40%, with the majority of the deaths occurring between 5 and 8 weeks of age. Chicks exhibiting moderate-to-severe right ventricular hypertrophy, as identified by ECG analysis at 1 week of age, were predisposed to development of ascites. Thus, the variability in ascites-related mortality observed in field cases may be directly related to the number of predisposed chicks at the time of placement in the broiler house.