Detection and Identification of Translocations by Increased Specific Nondisjunction in ASPERGILLUS NIDULANS

A meiotic technique for visual detection of translocations has been applied to ten mitotically identified interchanges, and three new translocations were discovered using this method. Testcrosses between "standard" strains and potential translocation strains-e.g. strains with newly induced mutants or descendants from translocation crosses-are inspected for the frequency of abnormal-looking colonies. In all heterozygous translocation crosses "abnormals" are increased at least tenfold compared to the average control level of 0.15%. Most of these are disomics, and can be recognized by their characteristic phenotypes. Each translocation produces a few specific types, since nondisjunction is increased mainly in the linkage groups involved in the translocation (50-100-fold over control values). Therefore, translocations were not only detected but often tentatively assigned to linkage groups from the analysis of the disomic progeny in crosses. In addition, this technique allows reciprocal and nonreciprocal translocations to be distinguished, since only the latter produce one-third phenotypically abnormal duplication progeny. While results are clearcut in most cases, occasionally problems are encountered, e.g. when morphological mutants segregate in crosses, or when other genetic factors which increase or reduce the frequency of nondisjunction are present in certain strains.     

Formation of hybrid anthranilate synthetase in vitro from components of Aspergillus and Neurospora

Glutamine-dependent anthranilate synthetase was produced in vitro by mixing the extracts of a trypA and a trypC mutant of Aspergillus nidulans. Neither mutant alone possessed this activity. The enzyme formed in the mixture had the properties of the wild-type anthranilate synthetase which, together with N-(5-phosphoribosyl) anthranilate (PRA) isomerase and indole 3-glycerol phosphate (InGP) synthetase, is found in a 10S multienzyme complex. Extracts of the trypA69 mutant contained a 6.5S protein as the active component—presumably the trypC ⁺ product—which in addition showed PRA isomerase and InGP synthetase activity. Extracts of the trypC801 mutant lacked all three enzyme activities but contained a 4.5S component—the trypA ⁺ gene product—which in vitro showed ammonia-dependent anthranilate synthetase activity. These mutants are analogous in their properties to certain tryp-2 and tryp-1 mutants of Neurospora. When complementary extracts of the two genera were mixed (Aspergillus trypA with Neurospora tryp-1 or Aspergillus trypC with Neurospora tryp-2), a hybrid glutamine-dependent anthranilate synthetase was obtained which showed less than half the activity produced in homologous combinations.This study was supported by Grant GB 22655 from the National Science Foundation to J.A.DeM.     

Significant increase in natural disturbance impacts on European forests since 1950

Over the last decades, the natural disturbance is increasingly putting pressure on European forests. Shifts in disturbance regimes may compromise forest functioning and the continuous provisioning of ecosystem services to society, including their climate change mitigation potential. Although forests are central to many European policies, we lack the long-term empirical data needed for thoroughly understanding disturbance dynamics, modeling them, and developing adaptive management strategies. Here, we present a unique database of >170,000 records of ground-based natural disturbance observations in European forests from 1950 to 2019. Reported data confirm a significant increase in forest disturbance in 34 European countries, causing on an average of 43.8 million m³ of disturbed timber volume per year over the 70-year study period. This value is likely a conservative estimate due to under-reporting, especially of small-scale disturbances. We used machine learning techniques for assessing the magnitude of unreported disturbances, which are estimated to be between 8.6 and 18.3 million m³/year. In the last 20 years, disturbances on average accounted for 16% of the mean annual harvest in Europe. Wind was the most important disturbance agent over the study period (46% of total damage), followed by fire (24%) and bark beetles (17%). Bark beetle disturbance doubled its share of the total damage in the last 20 years. Forest disturbances can profoundly impact ecosystem services (e.g., climate change mitigation), affect regional forest resource provisioning and consequently disrupt long-term management planning objectives and timber markets. We conclude that adaptation to changing disturbance regimes must be placed at the core of the European forest management and policy debate. Furthermore, a coherent and homogeneous monitoring system of natural disturbances is urgently needed in Europe, to better observe and respond to the ongoing changes in forest disturbance regimes.     

Reciprocal Translocations and Translocation Disomics of Aspergillus and Their Use for Genetic Mapping

Two new techniques are described for genetic mapping of reciprocal translocations in A. nidulans, which can be used to locate centromeres and meiotically unlinked markers. They both make use of unbalanced disomics from heterozygous translocation crosses. These are mainly hyperhaploids of two classes: either typical-looking n + 1 with a normal chromosome in addition to a haploid set containing the translocation, or translocation disomics. When large chromosome segments are involved, such disomics, as well as stable aneuploids and duplication types, show characteristic phenotypes and can be classified visually. The first method maps translocation breaks qualitatively, since translocated markers can be identified when translocation disomics are analyzed for heterozygous markers. The second method measures meiotic linkage of any marker to the translocation breaks when allele ratios in the balanced haploid sectors of either or both classes of disomics are determined: linked markers show reciprocal deviations from 1:1—In addition, it can be shown that frequencies of nondisjunction and recovery of specific translocation disomics both depend on the relative position of the break within a chromosome arm. Such information can provide a rough estimate of the positions of breaks for a new translocation.—Using these techniques, as well as mitotic mapping in homo- and heterozygous translocation diploids, four reciprocal translocations were mapped. From these results, information on the sequence and orientation of most of the "meiotic fragments" of the current maps (groups III, VI, VII and VIII) was obtained, and the position of the centromeres of groups VI and VII were identified. Translocation disomics are also used to map meiotically unlinked single genes, e.g. oliA of group VII, to specify chromosome segments.     

Prognostic Implications of Electroencephalographic Findings of Hypsarrhythmia in First Year of Life

One hundred and five children who had shown the electroencephalographic (E.E.G.) features of hypsarrhythmia in the first year of life (1956-62) were assessed in 1969 in respect of death and mental development. Irrespective of the presenting symptomatology, and to some extent irrespective of therapy, mortality in the group was of the order of one in four (mostly before the age of 3 years) and the incidence of mental subnormality in the survivors was 77%. Only 18 children attained fairly normal standards of mental development and could attend ordinary schools. It seems that whatever the clinical picture at the time, the presence of hypsarrhythmia in the E.E.G. of an infant is a physical sign of grave prognostic implications.     

Role of larval host plant experience and solanaceous plant volatile emissions in Tuta absoluta (Lepidoptera: Gelechiidae) host finding behavior

The tomato leafminer, Tuta absoluta (Lepidoptera: Gelechiidae), is considered to be a major pest that damages tomato (Solanum lycopersicum L; Solanaceae) crops in South American, European, and Mediterranean countries. This insect species is polyphagous (i.e., feeds on many types of food); hence, it could also develop on other cultivated host plants, principally solanaceous plants, such as potato (S. tuberosum L.; Solanaceae) and eggplant (S. melongena L.; Solanaceae). Therefore, we tested the hypothesis that host plant choice by adult T. absoluta is influenced by plant volatile organic compounds and larval host plant experience. One tomato cultivar (cv.) ‘Moneymaker’ and three potato cv. ‘Charlotte’ ‘Bintje,’ and ‘Nicola’ were tested. Using a flying tunnel, we observed that females reared on tomato preferred flying toward tomato and, to a lesser extent, potato cv. ‘Charlotte.’ These preferences might be explained by the high release of terpenes by these two plants. When conducting oviposition choice assays, we found no preference between tomato and potato in the number of eggs laid by females that had been previously reared on either host plant. This study indicates that the host finding behavior of T. absoluta is mediated by solanaceous volatiles, while oviposition behavior appears to depend on additional stimuli. These results provide baseline information for use in the development of new control strategies against T. absoluta using semiochemicals and plant breeding.     

Amino acids in carbonaceous chondrites

For almost 20 years laboratory experiments have advanced the concepts of chemical evolution, particularly with regard to formation of the amino acids. What has been generally lacking is concrete natural evidence for this chemical evolution hypothesis. The recent development of sophisticated analytical techniques and availability of carbonaceous chondrites with a minimum of terrestrial contamination has resulted in the identification of amino acids which provide strong evidence for a natural extraterrestrial chemical synthesis. Since the initial find in the Murchison meteorite (a type II carbonaceous chondrite) of both protein and nonprotein amino acids and amino acids with nearly equal abundances of D and L isomers, further studies have been carried out. These studies have revealed the presence of at least 35 amino acids; the population consists of a wide variety of linear, cyclic and polyfunctional amino acids which shows a trend of decreasing concentration with increasing carbon number. Investigations of the Murray meteorite (a type II carbonaceous chondrite) has produced similar results, but studies of the Orgueil meteorite (a type I carbonaceous chondrite) show only a limited suite of amino acids, some of which appear to be indigenous while others appear to be terrestrial contaminants. A sample of the Murchison meteorite was extracted with D₂O and in addition to free amino acids, showing no deuterium incorporation, some amino acids showed the presence of deuterium suggesting either a precursor(s) or hydrogendeuterium exchange which require(s) formation of carbon-hydrogen bonds.     

Mms Sensitivity of All Amino Acid-Requiring Mutants in Aspergillus and Its Suppression by Mutations in a Single Gene

All available amino acid-requiring mutants of Aspergillus nidulans were found to be hypersensitive to MMS (methyl methanesulfonate) to various degrees. On MMS media, secondary mutations could be selected which suppress this MMS sensitivity but do not affect the requirement. Many such mutations were analyzed and found to be alleles of one gene, smsA (= suppressor of MMS sensitivity), which mapped distal on the right arm of chromosome V. This gene is more likely to be involved in general regulation of amino acid biosynthesis than MMS uptake, since a variety of pathway interactions were clearly modified by smsA suppressors in the absence of MMS.