Comparative mapping of the wheat chromosome 5A Vrn-A1 region with rice and its relationship to QTL for flowering time

 The vernalization gene Vrn-A1 on chromosome 5A is the predominant gene determining the spring/winter habit difference in bread wheat. Vrn-A1 was physically mapped using a set of deletion lines which located it to the region of chromosome 5A flanked by deletion breakpoints 0.68 and 0.78. This interval was shown to be homoeologous to a region of rice chromosome 3 that contains the flowering-time QTL Hd-6, previously mapped in a Nipponbare×Kasalath cross, and FLTQ1, a novel QTL identified by analysis of 78 F₃ families derived from a cross of ‘IR20’ב63–83’. Possible relationships between Vrn-A1 and rice QTL are discussed. Analysis of the chromosome 5A deletion lines showed evidence for a second, more proximal flowering-time effect located between deletion breakpoints 0.56 and 0.64. The proximal part of chromosome 5A is homoeologous to rice chromosome 9, on which two QTL were detected in the ‘IR20ב63–83’ cross. The possible relationship between these effects is also discussed. Received: 23 December 1997 / Accepted: 12 January 1998     

Relative Ability of Orally Administered Lactobacillus murinus To Predominate and Persist in the Porcine Gastrointestinal Tract

Five porcine-derived Lactobacillus or Pediococcus isolates administered to pigs (n = 4), either singly or as a combination at ~10¹⁰ CFU per day varied with respect to intestinal survival and persistence. Two Lactobacillus murinus strains survived best and were excreted at ~10⁷ to 10⁸ CFU/g of feces. In contrast, Pediococcus pentosaceus DPC6006 had the lowest fecal count at ~10⁵ CFU/g and was excreted at a significantly lower level than both L. murinus strains. Fecal L. murinus DPC6003 counts were also significantly higher than both Lactobacillus salivarius DPC6005 and Lactobacillus pentosus DPC6004 (~10⁶ CFU/g). The L. murinus strains persisted for at least 9 days postadministration in both the feces and the cecum. Animals fed a combination of all five strains excreted ~10⁷ CFU of the administered strains/g, with L. murinus predominating, as determined by randomly amplified polymorphic DNA PCR. Postadministration, variation was observed between animals fed the strain combination, but in general, L. murinus DPC6002 and DPC6003 and L. pentosus DPC6004 predominated in the feces and the cecum while P. pentosaceus DPC6006 was detected only in the cecum. Fifteen days after the start of culture administration, mean fecal Enterobacteriaceae counts were significantly lower in some of the treatment groups. In addition, when mean preadministration counts were compared with those obtained after 21 days of culture administration, Enterobacteriaceae counts were reduced by ~87 to 98% in pigs fed L. salivarius DPC6005, P. pentosaceus DPC6006, L. pentosus DPC6004, and the culture mix. In conclusion, the porcine intestinal isolates have potential as probiotic feed additives for pigs, with differences in strain performance highlighting the advantages of using culture combinations.     

The lys5 mutations of barley reveal the nature and importance of plastidial ADP-Glc transporters for starch synthesis in cereal endosperm

Much of the ADP-Glc required for starch synthesis in the plastids of cereal endosperm is synthesized in the cytosol and transported across the plastid envelope. To provide information on the nature and role of the plastidial ADP-Glc transporter in barley (Hordeum vulgare), we screened a collection of low-starch mutants for lines with abnormally high levels of ADP-Glc in the developing endosperm. Three independent mutants were discovered, all of which carried mutations at the lys5 locus. Plastids isolated from the lys5 mutants were able to synthesize starch at normal rates from Glc-1-P but not from ADP-Glc, suggesting a specific lesion in the transport of ADP-Glc across the plastid envelope. The major plastidial envelope protein was purified, and its sequence showed it to be homologous to the maize (Zea mays) ADP-Glc transporter BRITTLE1. The gene encoding this protein in barley, Hv.Nst1, was cloned, sequenced, and mapped. Like lys5, Hv.Nst1 lies on chromosome 6(6H), and all three of the lys5 alleles that were examined were shown to carry lesions in Hv.Nst1. Two of the identified mutations in Hv.Nst1 lead to amino acid substitutions in a domain that is conserved in all members of the family of carrier proteins to which Hv.NST1 belongs. This strongly suggests that Hv.Nst1 lies at the Lys5 locus and encodes a plastidial ADP-Glc transporter. The low-starch phenotype of the lys5 mutants shows that the ADP-Glc transporter is required for normal rates of starch synthesis. This work on Hv.NST1, together with the earlier work on BRITTLE1, suggests that homologous transporters are probably present in the endosperm of all cereals.     

Persistent alterations in heart rate variability, baroreflex sensitivity, and anxiety-like behaviors during development of heart failure in the rat

Depressed heart rate variability and mood are associated with increased mortality in patients with congestive heart failure (CHF). Here autonomic indexes were assessed 3 and 7 wk after left coronary artery ligation in telemetered rats, after which anxiety-like behaviors were assessed in an elevated plus maze. Low frequency (LF) and high frequency (HF) heart rate variability were reduced in CHF rats 3 wk after infarction (LF, 1.60 +/- 0.52 vs. 6.97 +/- 0.79 ms(2); and HF, 1.53 +/- 0.39 vs. 6.20 +/- 1.01 ms(2); P < 0.01). The number of sequences of interbeat intervals that correlated with arterial pressure was decreased in CHF rats at 3 and 7 wk (week 3, 26.60 +/- 10.85 vs. 59.75 +/- 11.4 sequences, P < 0.05; and week 7, 20.80 +/- 8.97 vs. 65.38 +/- 5.89 sequences, P < 0.01). Sequence gain was attenuated in CHF rats by 7 wk (1.34 +/- 0.06 vs. 2.70 +/- 0.29 ms/mmHg, P < 0.01). Coherence between interbeat interval and mean arterial blood pressure variability in the LF domain was reduced in CHF rats at 3 (0.12 +/- 0.03 vs. 0.26 +/- 0.05 k(2), P < 0.05) and 7 (0.16 +/- 0.02 vs. 0.31 +/- 0.05 k(2), P < 0.05) wk. CHF rats invariably entered the open arm of the elevated plus maze first and spent more time in the open arms (36.0 +/- 15% vs. 4.6 +/- 1.9%, P < 0.05). CHF rats also showed a tendency to jump head first off the apparatus, whereas controls did not. Together the data indicate that severe autonomic dysfunction is accompanied by escape-seeking behaviors in rats with verified CHF.     

Oral Tolerance to Cancer Can Be Abrogated by T Regulatory Cell Inhibition

Oral administration of tumour cells induces an immune hypo-responsiveness known as oral tolerance. We have previously shown that oral tolerance to a cancer is tumour antigen specific, non-cross-reactive and confers a tumour growth advantage. We investigated the utilisation of regulatory T cell (Treg) depletion on oral tolerance to a cancer and its ability to control tumour growth. Balb/C mice were gavage fed homogenised tumour tissue – JBS fibrosarcoma (to induce oral tolerance to a cancer), or PBS as control. Growth of subcutaneous JBS tumours were measured; splenic tissue excised and flow cytometry used to quantify and compare systemic Tregs and T effector (Teff) cell populations. Prior to and/or following tumour feeding, mice were intraperitoneally administered anti-CD25, to inactivate systemic Tregs, or given isotype antibody as a control. Mice which were orally tolerised prior to subcutaneous tumour induction, displayed significantly higher systemic Treg levels (14% vs 6%) and faster tumour growth rates than controls (p<0.05). Complete regression of tumours were only seen after Treg inactivation and occurred in all groups - this was not inhibited by tumour feeding. The cure rates for Treg inactivation were 60% during tolerisation, 75% during tumour growth and 100% during inactivation for both tolerisation and tumour growth. Depletion of Tregs gave rise to an increased number of Teff cells. Treg depletion post-tolerisation and post-tumour induction led to the complete regression of all tumours on tumour bearing mice. Oral administration of tumour tissue, confers a tumour growth advantage and is accompanied by an increase in systemic Treg levels. The administration of anti-CD25 Ab decreased Treg numbers and caused an increase in Teffs. Most notably Treg cell inhibition overcame established oral tolerance with consequent tumor regression, especially relevant to foregut cancers where oral tolerance is likely to be induced by the shedding of tumour tissue into the gut.