In vitro tuberization and plant regeneration from multinodal segment culture of Habenaria bractescens Lindl., an Argentinean wetland orchid

Tuberization in many terrestrial orchids represents the most important physiological process for reproduction and survival. An in vitro controlled and reproducible tuberization and plant regeneration system was designed for Habenaria bractescens. Multinodal segments were incubated on Murashige and Skoog (MS) medium supplemented with different concentrations of N⁶-benzylaminopurine (BAP) and sucrose. After 45 days, the explants developed root tubers in vitro in 8 of the 12 media assayed. MS medium with 87.6 mM sucrose plus 4.4 μM BAP was one of the most effective for stimulating root tubers. Plants derived from in vitro root tubers were successfully transferred to the greenhouse without any acclimatization. The morphology and anatomy of the regenerated underground organs were examined to find identifying and distinguishing features. The protocol to regenerate root tubers of H. bractescens will be useful to study the basic aspects and control of tuberization and to carry out restoration programs.     

LIGNINOLYTIC ACTIVITY PATTERNS OF Pleurotus ostreatus OBTAINED BY SUBMERGED FERMENTATION IN PRESENCE OF 2,6-DIMETHOXYPHENOL AND REMAZOL BRILLIANT BLUE R DYE

The degradation of 2,6-dimethoxyphenol (DMP) and decolorization of Remazol brilliant blue R dye (RBB), added to culture media of Pleurotus ostreatus developed in submerged fermentation, and the laccase, manganese peroxidase and veratryl alcohol oxidase activities produced in these systems were evaluated. Both compounds were removed from the culture medium mainly by enzymatic action. These compounds decreased the specific growth rate and the effect on the maximal biomass values was not important. The enzymatic activities were increased by DMP and/or RBB; however, the DMP showed a higher inducer effect on all enzymes than RBB. On the other hand, the RBB showed a larger inducer effect on manganese peroxidase activity than on the laccases and veratryl alcohol oxidase activities. These results show that DMP was a better inducer of ligninolytic enzymes than dye, and the process of dye decolorization and degradation of DMP requires the action of all enzymes of the ligninolytic complex.     

Unauthorized Horizontal Spread in the Laboratory Environment: The Tactics of Lula,a Temperate Lambdoid Bacteriophage of Escherichia coli

We investigated the characteristics of a lambdoid prophage, nicknamed Lula, contaminating E. coli strains from several sources, that allowed it to spread horizontally in the laboratory environment. We found that new Lula infections are inconspicuous; at the same time, Lula lysogens carry unusually high titers of the phage in their cultures, making them extremely infectious. In addition, Lula prophage interferes with P1 phage development and induces its own lytic development in response to P1 infection, turning P1 transduction into an efficient vehicle of Lula spread. Thus, using Lula prophage as a model, we reveal the following principles of survival and reproduction in the laboratory environment: 1) stealth (via laboratory material commensality), 2) stability (via resistance to specific protocols), 3) infectivity (via covert yet aggressive productivity and laboratory protocol hitchhiking). Lula, which turned out to be identical to bacteriophage phi80, also provides an insight into a surprising persistence of T1-like contamination in BAC libraries.     

Therodamas tamarae, a new species of copepod (Poecilostomatoida: Ergasilidae) parasitic on Plagioscion squamosissimus (Heckel) from the Araguaia River, Brazil; with a key to the species of the genus

Therodamas tamarae n.sp. is described based on females removed from branchial filaments of Plagioscion squamosissimus (Teleostei, Sciaenidae) caught in a lake near the Araguaia River, State of Goiás, Brazil. The new species shares with Therodamas elongatus (Thatcher, 1986) the same host, a similar reaction from the host to the presence of the parasites, and the same general shape of body; in addition, the two species are from the Amazon basin. On the other hand, it resembles T. fluviatilis Paggi, 1976 in the structure of legs 1 to 4. An identification key for Therodamas species, as well as comments on the distribution of the species, are included.