Predisposition of Aster to Phialophora wilt

The susceptibility of Aster novi-belgii to infection by the vascular wilt pathogen Phialophora asteris varied according to the growing conditions to which the host was subjected before inoculation. Relatively low air temperature, high soil moisture, and soil nutrients rich in potassium or phosphorus were pre-inoculation conditions in which Aster became relatively susceptible. Increased resistance was favoured by growing plants at relatively high air temperatures, low soil moisture, and soil nutrients rich in nitrogen or calcium but low in potassium or phosphorus prior to inoculation.     

The Fate of 1,2-14C-(Chloroethyl) Phosphonic Acid (Ethephon) in Olive (Olea europea)

The translocation and metabolism of ethephon at pH 7.0 and its effect on abscission of olive fruit, were studied in attached and detached fruits. In detached olives, the lowest fruit removal force values were achieved when the fruits were treated at their proximal cavity and kept under humid conditions. Following application of ¹⁴C-ethephon to the proximal cavity 63% of the label was absorbed within 4 h; evolution of ¹⁴C-ethylene proceeded at a slow rate, mainly from ¹⁴C-ethephon remaining on the olive surface, totaling 37% of the applied ethephon in 20 days. ¹⁴C-ethephon disappeared rapidly after its application to olive on the tree. More ¹⁴C-ethephon could be extracted from olives on the trees after distal application than after proximal application. Since the response of detached olives to treatments with ethephon was similar to that of attached olives in regard to fruit removal force reduction, the former can be used for the study of many aspects of ethephon and ethylene metabolism in olives. In our study no ethephon metabolites other than ¹⁴C-ethylene could be detected after ¹⁴C-ethephon application to attached or detached olive fruits.     

Colonization of cellulose membranes by species of Verticillium

Verticillium dahliae Kleb. (from Brussels sprouts), non-pathogenic to tomato, and V. tricorpus Issac, a virulent pathogen to tomato, differed in their ability to colonize samples of commercial Cellophane, their rate of colonization being dependent upon external sources of carbohydrate. Cellophane and filter paper were both utilized in culture as the sole carbon source and it appears that both fungi have identical cellulase enzyme systems. Prolonged growth of the isolates is liquid medium containing sucrose as the carbon source resulted in lysis of the mycelium, which coincided with the production of polysaccharide material in culture.     

Guidelines for the Description of New Species of Lower Trypanosomatids1

Morphological, cultural, and biochemical criteria that have been used in describing lower trypanosomatids, genera Blastocrithidia, Crithidia, Leptomonas, Herpetomonas, Rhynchoidomonas, and Phytomonas are reviewed. Kinetoplast structure, carbohydrate utilization, electrophoretic mobilities of isoenzymes, and kDNA fingerprinting are among the recommended criteria for species differentiation. Temperature, pH, and osmolarity tolerance are useful growth parameters. Generic placement may be assisted by the determination of nitrogenous excretion products and ornithine-arginine cycle enzymes.     

Five Trypanosomatid Species of Insects Distinguished by Isoenzymes*

SYNOPSIS Blastocrithidia culicis, Crithidia deanei, Crithidia fasciculata, Herpetomonas samuelpessoai, Leptomonas seymouri and Leishmania tarentolae grown in cultures were compared by electrophoretic mobility for isoenzymes in 6 enzymes. All species were found distinct in these characteristics. Endosymbiotic C. deanei, which was identical to the aposymbiotic C. deanei in 5 enzymes, had an extra band in aspartate aminotransferase. No differences in isoenzymes were found between members of one species maintained in 2 different culture media.     

Verticillium wilt of sainfoin

A wilt disease of sainfoin caused by Verticillium Dahliae Kleb. is described, and it is shown that the fungus can penetrate sainfoin seedlings through unwounded roots as well as through ruptures caused by the emergence of lateral rootlets. V. Dahliae was isolated from naturally infected soil only in June, July and August, although another species, V. nigrescens , was obtained throughout the year.
Comparative studies of the longevity of cultures of V. Dahliae, V: albo-atrum and V. nigrescens proved that all are viable for at least 3 years on agar media. On sterilized wheat grains V. Dahliae dies within 8 weeks after inoculation, V. albo-atrum and V. nigrescens within 12 weeks, while the hyaline variants of the first two remain viable for 6 months.
Evidence was obtained that in artificially inoculated soil V. Dahliae persists mainly as microsclerotia. The fungus may also exist in the soil as hyaline mycelium or conidia, but only for a relatively short time.
The incidence of this disease in sainfoin is reduced by an increase in soil-water content, but is unaffected by the application of lime to the soil.     

Phylogenetic Distribution and Function of the Hypophysiotropic Hormones of the Hypothalamus

SYNOPSIS. Following the isolation, synthesis and subsequentdevelopment of specific and sensitive radioimmunoassays forthe hypothalamic hormones thyrotropin-releasing hormone (TRH),luteinizing hormone-releasing hormone (LH-RH) and growth hormonerelease-inhibiting hormone (somatostatin), it was recognizedthat these peptides were not localized solely in the hypothalamus,but were widely distributed throughout the mammalian nervoussystem. Somatostatin occurs outside the nervous system altogether,being located in the gastrointestinal tract of vertebrates whereit may have a physiologic role in the secretion of gastrointestinalhormones. TRH, also, has been located outside the nervous system,occurring in large quantities in the skin of Rana species whereit may be of physiologic importance in skin function. This tripeptideis found throughout the nervous system of vertebrate and invertebratespecies in situations where it has no pituitary-thyroid function.Thesepeptides are present in brain synaptosomes and enzymatic degradingsystems have been recognized for each in brain tissue. For TRH,specific receptors and synthesizing activity have been detectedoutside the hypothalamic-pituitary system. The anatomic location,phylogenetic distribution, neurophysiologic and behavioral effectsstrongly support a role for these substances in neuronal regulation,apart from control of pituitary secretion. Evolutionary studies,especially of TRH, suggest that their primary function may beas neurotransmitters.     

Phylogenetic Distribution and Significance of the Hypothalamic Releasing Hormones

SYNOPSIS. The mammalian hypothalamic releasing factors regulatingthyroid, gonadal and adrenal function as well as growth hormonesecretion have been isolated, characterized and their nucleotidesequences determined. In general, their hypophysiotropic effectsare replicated in lower vertebrates though thyrotropin releasinghormone (TRH) does not appear to stimulate thyroid functionin amphibia and fish. The releasing factors, or peptides structurallyrelated to these substances, are found throughout the CNS ofall vertebrates where they likely function as neurotransmittersor neuromodulators. High concentrations of TRH and other neuralpeptides includingsauvagine, which is related to corticotropinreleasing factor (CRF) and has CRF-like activity, are foundin amphibian skin, a neural crest derived tissue. mRNA extractedfrom the skin of Xenopus laevis was cloned and led to the identityof the DNA sequence of pre-pro TRH. Molecular variants of somatostatinhave been recognized from studies on the pancreatic islets ofthe anglerfish and catfish. Within mammalian species there isheterogeneity of growth hormone releasing factor (GRF), the44 (and 40) amino acid peptides isolated from a human(h) pancreatictumor. In the teleost brain-pituitary, 2 distinct hGRF-likeneuronal systems are present. Additionally, various molecularforms of hGRF exist in the fish brain showing structural changesfrom the human variety.