Integrated regulation of the photosynthetic gene family from Arabidopsis thaliana in transformed tobacco cells

Summary Expression of the three chlorophyll a/b binding protein (cab) genes of Arabidopsis thaliana was studied in transformed tobacco tissues. For each cab gene, approximately 1000 bp of the promoter region plus a portion of the structural gene was inserted into a promoter-expression vector such that a translational fusion between the cab gene and the promoter-less chloramphenicol acetyltransferase (cat) gene was formed. The constructed molecules were introduced into either cultured tobacco cells or tobacco leaves and the promoter activity was monitored as chloramphenicol acetyltransferase activity. The light-grown tissues exhibited 1.5- to 60-fold greater promoter activity than did dark-grown tissues. Expression of the cab promoters was tissue specific: activities were much stronger in green leaves than other tissues. The cab promoters were almost equally active in transformed calli or shoots derived from leaves. However, in cultured tobacco cells, one promoter was two to three times stronger than the other two. The chimeric gene fusion, cab-cat, segregated in the F1 generation as a dominant Mendelian trait.     

The rep region of pR plasmid regulates the expression of SOS system

Summary By using an artificial hybrid between phage and the pR plasmid, we have shown that the rep region of the pR plasmid encodes a function which regulates the expression of the muc genes (plasmid genes that are under the negative control of lexA and responsible for an increased rate of spontaneous mutagenesis and resistance to UV and chemicals). Expression of the muc genes was monitored by a fusion between the muc promoter and the lacZ structural gene. When E. coli cells containing such a fusion are infected by the hybrid pR phasmid, -galactosidase activity is enhanced, indicating that pR encodes an antagonist of lexA. By deletion mapping we have located the gene encoding the antagonist of lexA (bat) in the rep region of the plasmid. The bat gene product can also antagonize the cI repressor as shown by the observation that pR phasmids are virulent on a homoimmune lysogen. We have exploited this latter property to carry out genetic and functional analysis of the bat region. This region is organized as a classical operon where the expression of the bat structural gene is negatively regulated by a repressor gene that encodes a proteic product.     

Analysis of meiosis in triticale (XTriticosecale Wittmack) X rye (Secale cereale L.) F1 hybrids at three ploidy levels

Summary Triticales (XTriticosecale Wittmack) at three ploidy levels (8x, 6x, 4x, x=7) were crossed with diploid rye (Secale cereale L.) to produce a solitary hypopentaploid hybrid (2n=32), and a number of tetraploid (2n=4x=28) and triploid (2n=3x=21) hybrids. The hybrids exhibited a morphology which was intermediate between the parents. The number of bivalents ranged from 1–7 (4.65 per cell) in hypopentaploid, from 2–12 (7.13 per cell) in tetraploid and from 4–9 (6.84 per cell) in triploid hybrids. In 4x and 3x hybrids, trivalents and quadrivalents were also observed at low frequencies (range 0–1; mean 0.01–0.03 per cell). Chiasmata frequency was highest in triploid hybrids (12.44 per cell), lowest in hypopentaploid (5.37 per cell) and intermediate in tetraploids (10.54 per cell). More than 7¹¹ were found in 39.7% pollen mother cells (PMC's) in the 4x hybrids and in 5.0% PMCs in 3x hybrids. It is concluded that an increase in the relative proportion of wheat chromosomes in the hybrids had a slight suppression effect on homologous as well as homoeologous pairing of rye chromosomes. Contrary to this, the relative increase in rye complement promoted homoeologous pairing between wheat chromosomes. In triploid hybrids, the chiasmata frequency as well as the c value were the highest, suggesting that in tetraploid hybrids rye chromosomes had a reduced pairing (low frequency of ring bivalents).     

Regulation of blue-green algal buoyancy and bloom formation by light,inorganic nitrogen,C02, and trophic level interactions

In highly eutrophic ponds, buoyancy of the gas-vacuolate blue-green alga Anabaenopsis Elenkinii (Miller) was regulated by complex interactions between chemical and physical parameters, as well as by biological interactions between various trophic levels. Algal buoyancy and surface bloom formation were enhanced markedly by decreased light intensity, and to a lesser extent by decreased CO₂ availability and increased availability of inorganic nitrogen. In the absence of dense populations of large-bodied Cladocera, early season blooms of diatoms and green algae reduced light availability in the ponds thus creating conditions favorable for increased buoyancy and bloom formation by A. Elenkinii. The appearance of blue-green algal blooms could be prevented by a reduced density of planktivorous fish, which allowed development of dense cladoceran populations. The cladocerans limited the growth of precursory blooms of diatoms and green algae, and given the resulting clear-water conditions, buoyancy of A. Elenkinii was reduced, and blue-green algal blooms never appeared.     

Effects of starvation,chilling, and injury on endocrine gland function in Galleria mellonella

Starvation, chilling, and injury of last instar Galleria mellonella larvae typically elicit extra larval molts or a delay in pupation. The primary sites of action and the nature of the signals by which these treatments affect development are not known. However, since the connections of the brain to the nerve cord are crucial for the effects of starvation and chilling, these signals apparently affect the brain-centered program of developmental regulation via the nerve cord. Chilling, and occasionally starvation, cause extra larval molts in last instar larvae treated prior to the nervous inhibition of their corpora allata; release of a cerebral allatotropin, which stimulates the production of juvenile hormone, appears to be involved in this effect. After this time, a delay in pupation is the principal effect of starvation and chilling, and is apparently due to a temporal inhibition of the release of the prothoracicotropic hormone. Chilling also appears to inhibit unstimulated ecdysteroid production by the prothoracic glands. The effect of injury is not mediated by the nerve cord, but appears to involve an inhibitory humoral factor that affects either the brain or the prothoracic glands themselves. Injury also stimulates juvenile hormone production, an effect which is enhanced when the brain is separated from the nerve cord and which is evidenced by a delay of ecdysis and the occasional retention of some larval features in the ecdysed insects. None of the effects of these various treatments on the brain and the endocrine glands persist when the brains or glands are implanted into untreated hosts.     

Artifical diets and rearing of the nun moth, Lymantria monacha

Artificial diets were reviewed and two tested. The highest level of survival to the adult stage (72%) was obtained on a modified diet of Odell & Rollinson (1966). Rearing required 61 days for males and 70 days for females. Wing deformation occurred in 16% of the adults. The sex ratio ( : ) was 0.80. Average pupal weight was 281 mg for males and 368 mg for females. Females averaged 102 eggs (range 80–125 eggs). Neonates from field-collected egg masses started hatching on 6 December; frost was not necessary for hatching. Hatching could be postponed until at least 10 November of the following year by storing egg masses at-2°C. L. monacha can be maintained continuously in the laboratory.

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Zusammenfassung Eine Massenvermehrung der Nonne, Lymantria monacha (L.), trat in 1984 auf 500 ha Pinus sylvestris bei Budelerbergen (S.O. der Niederlande) auf und betraf 1985 eine Fläche von 2800 ha. Obwohl die Vermehrung durch eine Luftapplikation mit Dimilin 25 bekämpft werden konnte, wurden Untersuchungen begonnen zur Entwicklung von für die Umwelt sicheren Bekämpfungsmethoden, besonders die Anwendung von Virosen. Das Ziel bestand in der Virusproduktion in künstlichen Raupenzuchten. Die Nonne wurde bisher mit verschiedenen für andere Insektenarten oder speziell für diesen Zweck entwickelten künstlichen Nährböden gezüchtet. Da die Zusammensetzung dieser Nährböden und die Zuchtmethoden nicht veröffentlicht waren und da wenige Details über die Raupenentwicklung vorlagen, wurden modifizierten Nährböden von McMorran sowie von Odell & Rollinson für die Massenzucht der Nonne geprüft.

     

The relationship of calcium and parathyroid hormone in their effect on heart cells

Parathyroid hormone (PTH), the plasma concentration of which is raised in uremia, has been suggested as one of the agents responsible for the myocardial changes commonly seen in uremia. The effect of intact [1–84] PTH on rat heart cells grown in tissue culture has been studied. Addition of the hormone to the media significantly stimulated beating rate. The stimulation was directly proportional to the amount of PTH in the medium. Excessively high concentration of PTH caused immediate cessation of the beating, which was reversed by the addition of calcium to the medium. The extent of stimulation by PTH was inversely proportional to the calcium concentrations in the medium. Isoproterenol and phenylephrine at excessively high concentrations in the medium did not mimic the PTH effect either alone or together with PTH. When beating ceased due to verapamil the effect was not reversed by the addition of calcium to the medium.Calcium added to the myocytes seen after beating ceased reversed the effect and the cells started to beat again. Cells kept for a longer period in the arrested state were not revived by the addition of calcium.     

Comparison of sequences from the malB regions of Salmonella typhimurium and Enterobacter aerogenes with Escherichia coli K12: A potential new regulatory site in the interoperonic region

Summary The malE and malK genes from Salmonella typhimurium, and the MalEFG operon and a portion of malK from Enterobacter aerogenes were cloned and sequenced. Plasmid-borne malE genes from both species and the malF and malG genes from E. aerogenes were expressed normally in Escherichia coli, and their products function in maltose transport. This shows that the malB products from the three species are interchangeable, at least in the combinations tested. The general genetic organization of the malB region is conserved. Potential binding sites and distances between them are highly conserved in the regulatory intervals. An unexpected conserved region was detected, which we call the U box, and which could be another target for a regulatory protein. This hypothesis is supported by the presence of the U box in the regulatory, region of the pulA-malX operon in Klebsiella pneumoniae. The intergenic region between malE and malF from S. typhimurium and E. aerogenes, contains inverted repeats similar to the palindromic units (PU or REP) found at the same location in E. coli. The predicted amino acid sequence of the encoded proteins showed 90% or more identity in every pairwise comparison of species.