Determinants of the high-methionine trait in wild and exotic germplasm may have escaped selection during early cultivation of maize

The 18 kDa high-methionine δ-class zein gene from maize has been cloned, and its regulation, structure, and map position studied. These studies have shown that (i) zein genes may also contain tryptophan and lysine codons, (ii) the 18 kDa and the related 10 kDa zein gene are coordinately regulated, but their products accumulate to different levels in a genotype-dependent manner, (iii) the duplication of δ-zein genes probably involved unequal crossing over, (iv) no copy correction in either direction has occurred from teosinte to modern corn, and (v) the duplication of of the 18 kDa zein gene probably occurred before the tetraploidization of a progenitor chromosome. The work shows that important nutritional quality determinants like the high-methionine seed proteins are abundant in several exotic and wild corn varieties and low in most of the inbreds screened. The lack of a selectable phenotype for such quality traits during initial domestication and breeding of corn would have eliminated cis and trans regulatory determinants from the germplasm used in modern corn breeding. Examples of the high-methionine δ-class zeins shown here may be generally applicable in explaining the low nutritional quality of most present-day corn grown.     

Some structural features of the d-glucan from the seed of Mirabilis jalapa

The cotyledon of the seed of Mirabilis jalapa was found to contain a d-glucan. Methylation, periodate oxidation, and graded and enzymic hydrolysis studies were conducted to elucidate its structure. For every 38 d-glucosyl residues therein, 34 are (1→4)- and 3 are (1→3)-linked; the d-glucosyl unit at the branch point is linked through O-1, O-2, and O-4. In some places in the chain, there are at least three (1→3)-linked d-glucosyl residues in a sequence. Both α- and β-d-glucosidic linkages are present in the polysaccharide, the former preponderating. The d-glucan gave with iodine a faint blue color that had λ_max 420 nm.     

Activation of brain phenylethanolamine-N-methyltransferase by Triton-X-100: Time related differences in the enzyme activation

The effect of different concentrations of Triton-X-100 (0.2 to 5 %) on the activity of enzyme phenylethanolamine-N-methyltransferase (PNMT) in the brain and adrenal was studied. The addition of 0.2 % Triton-X-100 to the 0.9 % KCl homogenization media resulted in 180 % activation of the brain PNMT. The similar content of this detergent added to the adrenal PNMT preparation had no marked effect on enzyme activity. Rising Triton-X-100 concentrations from 0.2 % to 5 % resulted in higher activation of brain PNMT activity but the adrenal enzyme remained rather stable. An exposure of 15 minutes of brain PNMT preparation to Triton-X-100 was the optimal interval to evoke the maximal increase in enzyme activity. This activation of brain PNMT by Triton-X-100 was observable up to 24 hours after the addition of the detergent.     

Affinity chromatography of pig heart fumarase.

2-(5'-Phenylpentyl)fumaric acid was shown to be a competitive inhibitor (Ki 0.5 mM) of pig heart fumarase. After nitration of the aromatic ring, reduction to the amine and diazotization, the acid was attached via azo linkages to a Sepharose 4B-tyramine matrix. The resulting adsorbent was used for the affinity chromatography of crude fumarase, purifications of approx. 20-fold being obtained by specific elution with 0.01 M-citrate.     

The relationship of the zone polarizing activity to supernumerary limb formation (twinning) in the chick wing bud.

The role of the polarizing zone mesoderm in development of supernumerary distal wing parts after 180° rotation of the wing tip was investigated. Postaxial mesoderm with and without polarizing tissue was repositioned preaxially in the wing bud and duplications occurred only when polarizing zone tissue was included. When the polarizing zone was removed and the distal tip of the wing reoriented, no duplication resulted. Similarly when the polarizing zone was removed, the distal tip reoriented and postaxial, nonpolarizing mesoderm introduced to restore the tissue mass of the stump, no twinning occurred. However, with the distal aspect reoriented on a stump from which postaxial, nonpolarizing mesoderm was removed, twinning occurred in 92.9% of the cases. Further, when the polarizing zone was removed, the distal aspect reoriented and a small piece of polarizing tissue returned, twinning resulted in 93.5% of the cases. These results indicate that polarizing zone tissue is required for the twinning that results after 180° rotation of the wing tip.     

Mitochondrial haplogroup N1a phylogeography,with implication to the origin of European farmers

Background  

Tracing the genetic origin of central European farmer N1a lineages can provide a unique opportunity to assess the patterns of the farming technology spread into central Europe in the human prehistory. Here, we have chosen twelve N1a samples from modern populations which are most similar with the farmer N1a types and performed the complete mitochondrial DNA genome sequencing analysis. To assess the genetic and phylogeographic relationship, we performed a detailed survey of modern published N1a types from Eurasian and African populations.