Construction of ‘compound’ rust resistance genes in maize

Summary The Rp1 locus of maize is a complex rust resistance locus where multiple resistance genes are clustered. Rare recombination events between Rp1 genes or alleles can produce two or more detectable genes linked in coupling phase. Such compound genes can then be manipulated as a single gene in breeding programs. Several compound Rp1 genes, each carrying two or three tightly linked resistance genes, were constructed to test their utility in controlling common rust. While none of the lines carrying single Rp1 genes were resistant to all of the characterized North American P. sorghi biotypes, most of the two component and all of the three component Rp1 complexes were resistant. The potential for utilization of compound resistance genes in other crop species is discussed.     

Binding of [14C]DDT and [14C]dicyclohexylcarbodi-imide to a lipoprotein of the membrane sector of mitochondrial ATpase

Intact mitochondria, isolated from red coxal muscle of the American cockroach (Periplaneta americana L.), were incubated in the presence of 1,1,1-trichloro-2,2-bis(4-chloro[¹⁴C]phenyl)ethane ([¹⁴C]DDT) to isolate a suspected binding site for DDT in the membrane sector of the mitochondrial ATPase. The requirements for the binding of DDT were compared with those for the binding of dicyclohexyl[¹⁴C]carbodi-imide([¹⁴C]DCCD), a potent inhibitory probe of mitochondrial ATPase activity. [¹⁴C]DDT appeared to bind to a proteolipid of the membrane sector, which also binds [¹⁴C]DCCD. Exchange experiments, with [¹⁴C]DCCD, [¹⁴C]DDT and unlabelled DDT at different concentrations, indicated that DDT and DCCD may be acting on a similar protein. This protein may act as the energy transducing protonophore required for the synthesis and hydrolysis of ATP in coupled mitochondria. Inhibition of mitochondrial ATPase activity may be a consequence of DDT and DCCD binding to this proteolipid protonophore, resulting in the disruption of energy transduction in muscle and nerve.     

Isolation of infectious pancreatic necrosis (IPN) virus from non-salmonid fish

Abstract. The isolation and characterization of infectious pancreatic necrosis (IPN) virus from a goldfish, discus fish and bream is described. The fish from which the isolates were recovered showed no pathological signs of IPN. All three virus isolates were neutralized by antiserum to IPN, strain Ab, but not by antiserum to the Sp or VR-299 strains. They were morphologically identical to IPN virus in negative stain electron microscopy, grew in the cytoplasm of BF-2 cells, as shown by immuno-fluorescence and, like IPNV, were stable to heating, lipid solvents and acid pH.     

Effect of Soil–matric Potential and Phylloplanes of Rotation-crops on the Survival of a Bioluminescent Xanthomonas campestris pv. campestris

The survival of the bacterial pathogen, Xanthomonas campestris pv. campestris (Xcc), was studied in plant debris-infested soil with different matric potentials (0, –10, –30, –50, –100, –200, and –900kPa), and on the phylloplane of crops used for rotation with cabbage. Populations of cellulolytic and proteolytic microorganisms were studied in relation to soil matric potential and Xcc. The survival of Xcc was negatively correlated (r=–0.710; P=0.06) with soil matric potential and with the abundance of cellulolytic microorganisms (P=0.05). In saturated soil, Xcc survived for only 19–28 days, while at –900kPa there was no significant change in the bacterial population within this period. Survival of Xcc on the phylloplane of cabbage (Brassica oleracea var. capitata) (host) was similar to that on mustard and lettuce (48 days), whereas the pathogen was detected for only 9 days on rice. It appears that high matric potentials reduced populations of Xcc in soil, whereas epiphytic survival of this pathogen depended on the plant species.     

Virulence of Flavobacterium branchiophilum in experimentally infected salmonids

Abstract. The ability of selected strains of Flavobacterium branchiophilum to attach to and colonize the gills of five species of teleosts (four salmonid and one cyprinid) and cause mortality was investigated. In virulence studies with F. branchiophilum strain LAB4a, cumulative mortality was dose-dependent in rainbow trout, Oncorhynchus mykiss (Walbaum), and ranged from 0 to 75%. However, regardless of dose, the relative amount of gill-associated F. branchiophilum antigen increased 1 h after challenge. The gill-associated F. branchiophilum antigen in fish which survived (moribund fish) increased by four to six times compared to that detected on the gills 1 h after challenge. The gill-associated antigen on moribund fish was not significantly different from that on the gills of dead fish. Flavobacterium branchiophilum strain LAB4a also attached to the gills of brook trout, Salvelinus fontinalis (Mitchell), rainbow trout, chinook salmon, Oncorhynchus tshawytscha (Walbaum), Arctic charr, Salvelinus alpinus (L.), and common shiners, Luxilus cornutus (Mitchell), following a 1-h bath exposure, and caused mortality in all species. The virulence of eight strains of F. branchiophilum for rainbow trout was examined. Both virulent and avirulent strains adhered to the gills following bath exposure (fimbriae were observed on all strains), but only virulent strains had the capacity to further colonize the gills and cause mortality.     

Proliferative kidney disease in rainbow trout Salmo gairdneri Richardson

Abstract. Two entirely separate outbreaks of PKD are described in an attempt to properly define the condition and enable it to be differentiated from other diseases of a similar nature. Losses of up to 75% of fingerling rainbow trout were recorded in one outbreak, illustrating the potentially serious nature of the disease. Although the kidneys showed the most obvious pathological changes, other organs were also affected. The host response was granulomatous in type, the foci of each cellular reaction being 5-20 μm eosinophilic cells considered to be parasitic. The cytoplasm of these cells contained numerous electron dense bodies some with a tail, but each with an electron lucent bar always orientated at right angles to the plasmalemma whenever they were near it. The most obvious cytoplasmic inclusion of these 'parasites' were other cells numbering up to five or six, each with its own nucleus and nucleolus, but devoid of any of the small electron dense bodies. The significance of either of these inclusions is unknown.
A limited differential diagnosis is given, and the argument presented that the condition PKD is the result of infection by a parasite, possibly an amoeba, in combination with poor quality water.     

Behavior disruption in Cebus monkeys as a function of injected substances

Intraperitoneal injections of blood substances from schizophrenic or stressed normal human donors into primates trained to perform a precision timing task resulted in significant prolongation of time taken to complete the task as compared with injections of blood substances from normal donors.