Rapid and high-precision marker assisted backcrossing to introgress the <Emphasis Type="Italic">SUB1</Emphasis> QTL into BR11, the rainfed lowland rice mega variety of Bangladesh

Flooding is one of the major hazards of rice production for the rainfed lowland rice ecosystem, and tolerant cultivars are urgently needed to help protect farmers from submergence damage. A quick and efficient strategy was implemented to introgress SUB1, a major QTL for submergence tolerance, into a rainfed lowland mega variety BR11 of Bangladesh by only two backcrosses and one selfing generation. In marker-assisted backcrossing (MABC), one tightly-linked simple sequence repeat (SSR) and two gene-based markers, four flanking SSR and 116 background SSR markers were used for foreground, recombinant and background selection, respectively, in backcrosses between a SUB1 donor IR40931-33-1-3-2 and BR11. BR11-Sub1, identified in a BC₂F₂ plant, possessed BR11 type SSR alleles on all fragments analyzed except the SUB1 QTL. The introgression size in BR11-Sub1 was 800 Kb indicating approximately 99.8% identity to BR11. BR11-Sub1 along with other introgression lines showed submergence tolerance similar to the tolerant parent. Yield, yield-component parameters and grain physico-chemical properties showed successful recovery of the BR11 traits in BR11-Sub1, with yield potential ranging from 5.2 to 5.6 t/ha, not significantly different from the recurrent parent mega variety BR11. Producing a large number (~1000) of backcross F₁ plants was considered essential to achieve recombination on both sides of the gene, limiting linkage drag with only two backcrosses. A large number of background markers ensured proper recovery of the recurrent parent genome in the BC₂F₂ generation. The study demonstrates a rapid and highly precise strategy to introgress a major QTL by BC₂F₂ generation into a modern rice variety using an unadapted donor. The variety can replace BR11 on more than 2 million of ha in Bangladesh and provide major increases in rice production.     

Carrier state in human acatalasemia

The heterozygous carrier state of a rare hereditary disease, acatalasemia, has been defined biochemically. Affected homozygotes have no blood catalase activity, whereas heterozygotes show activities intermediate between this inactivity and the activity of normal controls, without overlap. Pedigrees show a high frequency of consanguineous marriages.     

Identification and characterization of a neuron-specific nuclear antigen in Drosophila

An antigen found only in neuronal nuclei of Drosophila melanogaster is revealed by staining with a monoclonal antibody (Mab44C11). This antigen appears early in development, before neurons show any other signs of antigenic or morphologic differentiation, and persists throughout development. This nuclear staining permits reliable detection of neurons in developmental studies of wild-type and mutant flies. Protein immunoblot analyses and immune precipitation experiments show that the neuronal nuclear antigen is a 50-kilodalton polypeptide.     

Heparin affinity: purification of a tumor-derived capillary endothelial cell growth factor

A tumor-derived growth factor that stimulates the proliferation of capillary endothelial cells has a very strong affinity for heparin. This heparin affinity makes it possible to purify the growth factor to a single-band preparation in a rapid two-step procedure. The purified growth factor is a cationic polypeptide, has a molecular weight of about 18,000, and stimulates capillary endothelial cell proliferation at a concentration of about 1 nanogram per milliliter.     

A giant sauropod dinosaur from an Upper Cretaceous mangrove deposit in Egypt

We describe a giant titanosaurid sauropod dinosaur discovered in coastal deposits in the Upper Cretaceous Bahariya Formation of Egypt, a unit that has produced three Tyrannosaurus-sized theropods and numerous other vertebrate taxa. Paralititan stromeri is the first tetrapod reported from Bahariya since 1935. Its 1.69-meter-long humerus is longer than that of any known Cretaceous sauropod. The autochthonous scavenged skeleton was preserved in mangrove deposits, raising the possibility that titanosaurids and their predators habitually entered such environments.     

Lateral hopping of molecules induced by excitation of internal vibration mode

We demonstrate electron-stimulated migration for carbon monoxide (CO) molecules adsorbed on the Pd(110) surface, which is initiated by the excitation of a high-frequency (HF) vibrational mode (C-O stretching mode) with inelastic tunneling electrons from the tip of scanning tunneling microscopy. The hopping phenomenon, however, cannot be detected for CO/Cu(110), even though the hopping barrier is lower than in the CO/Pd(110) case. A theoretical model, which is based on the anharmonic coupling between low-frequency modes (the hindered-translational mode related to the lateral hopping) and the HF mode combined with electron-hole pair excitation, can explain why the hopping of CO is observed on Pd(110) but not on Cu(110).     

Uroporphyrinogen decarboxylase structural mutant (Gly281----Glu) in a case of porphyria

Uroporphyrinogen decarboxylase deficiency in man is responsible for familial porphyria cutanea tarda and hepatoerythropoietic porphyria. A recent study of a family with hepatoerythropoietic porphyria showed that the enzyme defect resulted from rapid degradation of the protein in vivo. Cloning and sequencing of a complementary DNA for the mutated gene revealed that the mutation was due to the replacement of a glycine residue by a glutamic acid residue at position 281. This base change leads to a protein that is very rapidly degraded in the presence of cell lysate. Characterization of the mutation will allow comparison of this defect in a homozygous patient with defects in other patients with familial porphyria cutanea tarda.