For finite q, we classify the countable, descendant-homogeneous digraphs in which the descendant set of any vertex is a q-valent tree. We also give conditions on a rooted digraph Γ which allow us to construct a countable descendant-homogeneous digraph in which the descendant set of any vertex is isomorphic to Γ. 2010 Mathematics Subject Classification: 05C20, 05C38, 20B27

The serological interrelationships between eleven viruses in the turnip yellow mosaic virus group (tymoviruses) were studied with 2% antisera from 48 rabbits. Antisera from different rabbits and from different bleedings of the same rabbit showed considerable differences in their homologous and heterologous reactivities. A classification based on average serological differentiation indices is pr...

The survival and growth of Listeria monocytogenes on fresh lettuce (Lactuca sativa), cucumber (Cucumis sativus) epidermis and parsley (Petroselinum sativum) under different relative humidity (RH) conditions and storage temperatures was studied. Inoculated vegetable pieces were stored at 10C for 7 days, 20C for 5 days, and 30C for 24 h, and at 53 and 90% RH. L. monocytogenes was enumerated perio...

Large and rapid increases in the activities of two enzymes of general phenylpropanoid metabolism, phenylalanine ammonia-lyase and 4-coumarate:CoA ligase, occurred in suspension-cultured parsley cells (Petroselinum hortense) treated with an elicitor preparation from Phytophthora megasperma var. sojae. Highest enzyme activities were obtained with an elicitor concentration similar to that required...

The serological interrelationships between eleven viruses in the turnip yellow mosaic virus group (tymoviruses) were studied with 286 antisera from 48 rabbits. Antisera from different rabbits and from different bleedings of the same rabbit showed considerable differences in their homologous and heterologous reactivities. A classification based on average serological differentiation indices is p...

Microtheca spp. (Coleoptera: Chrysomelidae) are insect pests primarily related to Brassicaceae crops. In the State of Rio Grande do Sul (RS), southern Brazil, they are found on forage turnip, Raphanus sativus L. var. oleiferus Metzg., which is commonly grown during fall/winter seasons. This work reports the predation of Microtheca spp. larvae by Toxomerus duplicatus Wiedemann, 1830 (Diptera: Sy...

Polygalacturonase (PG) was purified from Erwinia carotovora EC. A hybrid cosmid, pSH711, that encodes PG activity but not pectate lyase activity was identified from an E. carotovora genomic library by an immunological screening method. A cell extract of Escherichia coli cells containing pSH711 was able to produce plant tissue maceration when spotted on carrot, potato, or turnip slices. In addit...

Parsley is a plant widely used in cooking as condiment and it has potential for pharmaceutical use due to flavonoids production, including the apiin, which antioxidant activity. The current study investigates influence of N fertilization on biomass soluble fractions, total apiin parsley plants at 28 56 days after germination (DAG). experiment was carried out greenhouse under different levels: n...