Transport regulation of recombinant gene expression in E. coli and B. subtilis

Expression kinetics of the lactose (lac) operon in Escherichia coli are reviewed for both wild-type and recombinant cell cultures under chemostatic conditions. A unified model which involves regulation of active inducer (lactose) transport, promoter-operator regulated expression of the lac operon, glucose-mediated inducer exclusion, and catabolite repression is summarized and supporting data is shown to verify its accuracy. The synthesis of alpha-amylase with a recombinant form of Bacillus subtilis is also reviewed to point out generic features in transport regulation, the lac operon model providing a point of departure. While there are many similarities in the influence of transport on both regulating models, there are also important differences. In a chemostat system, the synthesis of alpha-amylase is nongrowth associated, while beta-galactosidase is a growth-associated enzyme. Nevertheless, transport regulation is an important feature in both instances.     

Étude pédologique comparative de l'habitat et de l'environnement d'anacanthotermes ochraceus (Burgmeister)

Summary Anacanthotermes ochraceus (Burgmeister), in the oasis of Béni-Abbès (Sahara) will establish its colonies only in the low eathern garden walls and in the clay and straw walls of the houses, where it can find both the water and the malleable clayed materials it requires.Soil analyses have given information on the physico-chemical characteristics of some of the termitaria and of the surrounding sand-hill.The organic matter in the termitarium comes both from the soil and the excrement of the termite. It is high in carbon and low in nitrogen (C/N=2,5), and its mineralization in the présense of gravitational water may result in a loss of mobilizable elements such as the bases.Both the Ph and the aeration of the termitarium favour the mineralization of nitrogenous waste material by bacterial agency.The distribution of calcium carbonate and the condition in which it occurs are more important than the total amount present on account of the part it plays in the texture and structure of the materials, of which the termitarium is composed.A statistical granulometric study of the sand fraction with the results expressed as polar coordinates enables, in comparison with those obtained by mechanical analysis, the texture of the materials colonised byAnacanthotermes ochraceus (Burgmeister) to be defined.

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Zusammenfassung In der Oase Béni-Abbés (Sahara) gründen dieAnacanthotermes ochraceus (Burgmeister) ihre Kolonien nur in den Wänden der Gärten und in den Mauern der Wohnungen. Dort finden sie das nötige Wasser und die tonigen Plastikmaterialien.Die Bodenanalysen geben Auskunft über einige der characteristichen physikalischchemischen Eigenschaften der Materialien in der Termitenbauten und in dem benachbartem Erg.Das organische Material in den Termitenbauten stammt einerseits aus dem Boden und andererseits aus den Ausscheidungen der Termiten. Reich an Kohlenstoff und arm an Stickstoff (C/N=2,5) kann seine Mineralisation, in Gegenwart von gravifischem Wasser, einen Verlust von einsatzfähigen Elementen, wie den Laugen, nach sich ziehen.Die Bedingungen des Ph und der Belüftung der Termitenbauten sind günstig für eine Mineralisation der stikstoffhaltigen Abfallstoffe auf bakteriellem Wege.Die Verteilung und die Beschaffenheit des CO₃Ca sind dort wichtiger als ihre Gesamtauswertung. Der Grund dafür ist die Rolle, die sie auf der Ebene der Textur und des Aufbaus der Materialen in den Termitenbauten spielen.Die Untersuchung der sandigen Bruchstücke durch die granulometrischen Statistiken in Polarkoordinaten, verglichen mit den Ergebnissen der granulometrischen Analyse, erlauben eine Erklärung der Textur der mit Beschlag belegten kolonisierten Materialen durch dieAnacanthotermes ochraceus (Burgmeister).

     

Water deficit-induced changes in abscisic Acid, growth, polysomes, and translatable RNA in soybean hypocotyls

Soybean seedlings (Glycine max L.) were germinated and dark-grown in water-saturated vermiculite (water potential = −0.01 megapascal) for 48 hours, then transferred either to water-saturated vermiculite or to low water potential vermiculite (water potential = −0.30 megapascal). A decrease in growth rate was detectable within 0.8 hour post-transfer to low water potential vermiculite. A fourfold increase in the abscisic acid content of the elongating region was observed within 0.5 hour. At 24 hours post-transfer, hypocotyl elongation was severely arrested and abscisic acid reached its highest measured level: 3.7 nanograms per milligram dry weight (74-fold increase). A comparison of the polyA⁺ RNA populations isolated at 24 hours post-transfer from the elongating region of water-saturated and low water potential vermiculite-grown seedlings was made by two-dimensional (isoelectric focusing-sodium dodecyl sulfate) polyacrylamide gel analysis of in vitro translation products. It revealed both increases and decreases in the relative amounts of a number of translation products. Rewatering seedlings grown in low water potential vermiculite at 24 hours post-transfer led to a total recovery in growth rate within 0.5 hour, while abscisic acid in the elongating hypocotyl region required 1 to 2 hours to return to uninduced levels. Application of 1.0 millimolar (±) abscisic acid to well-watered seedlings resulted in a 48% reduction in hypocotyl growth rate during the first 2 hours after treatment. Plants treated with abscisic acid for 24 hours had a lower polysome content than control plants. However, hypocotyl growth inhibition in abscisic acid-treated seedlings preceded the decline in polysome content.     

DNA repair and replication in human fibroblasts treated with (±)-r-7,t-8-dihydroxy-t-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene

DNA repair and replication were examined in diploid human fibroblasts after treatment with (±)-r-7,t-8-dihydroxy-t-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (BPDE-I). Unscheduled DNA synthesis exhibited a linear response to BPDE-I concentrations up to 1.5 μM and a saturation plateau after higher concentrations. Maximal unscheduled DNA synthesis was observed in the first hour after treatment with synthesis diminishing progressively thereafter. Half-maximal unscheduled DNA synthesis was seen within 4–6 h after treatment with 0.7 μM BPDE-I. DNA replication was inhibited by BPDE-I in a dose- and time-dependent fashion. The mechanisms of this inhibition were characterized by velocity sedimentation of pulse-labeled nascent DNA in alkaline sucrose gradients. Very low concentrations of BPDE-I (0.03 and 0.07 μM) were found to inhibit replicon initiation by up to 50% within 30–60 min after treatment. Recovery of initiation following these low concentrations was evident within 3 h after treatment. Higher concentrations of carcinogen inhibited DNA synthesis in active replicons. This effect was manifested by a reduction in incorporation of precursor into replication intermediates of greater than 1·10⁷ Da with the concurrent production of abnormally small nascent DNA. When viewed 45 min after treatment with 0.17 μM BPDE-I the combination of these two effects partially masked the inhibition of replicon initiation. However, even after treatment with 0.33 μM BPDE-I an effect on initiation was evident. These results reveal a pattern of response to BPDE-I that is quite similar to that produced by 254 nm radiation.     

The effects of temperature and nutrients on the growth and dynamics of toxic and non-toxic strains of Microcystis during cyanobacteria blooms

In temperate latitudes, toxic cyanobacteria blooms often occur in eutrophied ecosystems during warm months. Many common bloom-forming cyanobacteria have toxic and non-toxic strains which co-occur and are visually indistinguishable but can be quantified molecularly. Toxic Microcystis cells possess a suite of microcystin synthesis genes (mcyA–mcyJ), while non-toxic strains do not. For this study, we assessed the temporal dynamics of toxic and non-toxic strains of Microcystis by quantifying the microcystin synthetase gene (mcyD) and the small subunit ribosomal RNA gene, 16S (an indicator of total Microcystis), from samples collected from four lakes across the Northeast US over a two-year period. Nutrient concentrations and water quality were measured and experiments were conducted which examined the effects of elevated levels of temperatures (+4 °C), nitrogen, and phosphorus on the growth rates of toxic and non-toxic strains of Microcystis. During the study, toxic Microcystis cells comprised between 12% and 100% of the total Microcystis population in Lake Ronkonkoma, NY, and between 0.01% and 6% in three other systems. In all lakes, molecular quantification of toxic (mcyD-possessing) Microcystis was a better predictor of in situ microcystin levels than total cyanobacteria, total Microcystis, chlorophyll a, or other factors, being significantly correlated with the toxin in every lake studied. Experimentally enhanced temperatures yielded significantly increased growth rates of toxic Microcystis in 83% of experiments conducted, but did so for non-toxic Microcystis in only 33% of experiments, suggesting that elevated temperatures yield more toxic Microcystis cells and/or cells with more mcyD copies per cell, with either scenario potentially yielding more toxic blooms. Furthermore, concurrent increases in temperature and P concentrations yielded the highest growth rates of toxic Microcystis cells in most experiments suggesting that future eutrophication and climatic warming may additively promote the growth of toxic, rather than non-toxic, populations of Microcystis, leading to blooms with higher microcystin content.     

A calcaneus attributable to the primitive late eocene anthropoid Proteopithecus sylviae: Phenetic affinities and phylogenetic implications

A well‐preserved calcaneus referrable to Proteopithecus sylviae from the late Eocene Quarry L‐41 in the Fayum Depression, Egypt, provides new evidence relevant to this taxon's uncertain phylogenetic position. We assess morphological affinities of the new specimen using three‐dimensional geometric morphometric analyses with a comparative sample of primate calcanei representing major extinct and extant radiations (n = 58 genera, 106 specimens). Our analyses reveal that the calcaneal morphology of Proteopithecus is most similar to that of the younger Fayum parapithecid Apidium. Principal components analysis places Apidium and Proteopithecus in an intermediate position between primitive euprimates and crown anthropoids, based primarily on landmark configurations corresponding to moderate distal elongation, a more distal position of the peroneal tubercle, and a relatively “unflexed” calcaneal body. Proteopithecus and Apidium are similar to cercopithecoids and some omomyiforms in having an ectal facet that is more tightly curved, along with a larger degree of proximal calcaneal elongation, whereas other Fayum anthropoids, platyrrhines and adapiforms have a more open facet with less proximal elongation. The similarity to cercopithecoids is most plausibly interpreted as convergence given the less tightly curved ectal facets of stem catarrhines. The primary similarities between Proteopithecus and platyrrhines are mainly in the moderate distal elongation and the more distal position of the peroneal tubercle, both of which are not unique to these groups. Proteopithecus and Apidium exhibit derived anthropoid features, but also a suite of primitive retentions. The calcaneal morphology of Proteopithecus is consistent with our cladistic analysis, which places proteopithecids as a sister group of Parapithecoidea. Am J Phys Anthropol 151:372–397, 2013.© 2013 Wiley Periodicals, Inc.     

Welcome back New Zealand: regional biogeography and Gondwanan origin of three endemic genera of mite harvestmen (Arachnida, Opiliones, Cyphophthalmi)

Aim Biogeographers have long been intrigued by New Zealand’s biota due to its unique combination of typical ‘continental’ and ‘island’ characteristics. The New Zealand plateau rifted from the former supercontinent Gondwana c. 80 Ma, and has been isolated from other land masses ever since. Therefore, the flora and fauna of New Zealand include lineages that are Gondwanan in origin, but also include a very large number of endemics. In this study, we analyse the evolutionary relationships of three genera of mite harvestmen (Arachnida, Opiliones, Cyphophthalmi) endemic to New Zealand, both to each other and to their temperate Gondwanan relatives found in Australia, Chile, Sri Lanka and South Africa. Location New Zealand (North Island, South Island and Stewart Island). Methods A total of 94 specimens of the family Pettalidae in the suborder Cyphophthalmi were studied, representing 31 species and subspecies belonging to three endemic genera from New Zealand (Aoraki, Neopurcellia and Rakaia) plus six other members of the family from Chile, South Africa, Sri Lanka and Australia. The phylogeny of these taxa was constructed using morphological and molecular data from five nuclear and mitochondrial genes (18S rRNA, 28S rRNA, 16S rRNA, cytochrome c oxidase subunit I and histone H3, totalling c. 5 kb), which were analysed using dynamic as well as static homology under a variety of optimality criteria. Results The results showed that each of the three New Zealand cyphophthalmid genera is monophyletic, and occupies a distinct geographical region within the archipelago, grossly corresponding to palaeogeographical regions. All three genera of New Zealand mite harvestmen fall within the family Pettalidae with a classic temperate Gondwanan distribution, but they do not render any other genera paraphyletic. Main conclusions Our study shows that New Zealand’s three genera of mite harvestmen are unequivocally related to other members of the temperate Gondwanan family Pettalidae. Monophyly of each genus contradicts the idea of recent dispersal to New Zealand. Within New Zealand, striking biogeographical patterns are apparent in this group of short‐range endemics, particularly in the South Island. These patterns are interpreted in the light of New Zealand’s turbulent geological history and present‐day patterns of forest cover.     

Comparing urban food system characteristics and actions in US and Indian cities from a multi‐environmental impact perspective: Toward a streamlined approach

Food action plans in many global cities articulate interest in multiple objectives including reducing in‐ and trans‐boundary environmental impacts (water, land, greenhouse gas (GHG)). However, there exist few standardized analytical tools to compare food system characteristics and actions across cities and countries to assess trade‐offs between multiple objectives (i.e., health, equity) with environmental outcomes. This paper demonstrates a streamlined model applied for analysis of four cities with varying characteristics across the United States and India, to quantify system‐wide water, energy/GHG, and land impacts associated with multiple food system actions to address health, equity, and environment. Baseline diet analysis finds key differences between countries in terms of meat consumption (Delhi 4; Pondicherry 16; United States 59, kg/capita/year), and environmental impact of processing of the average diet (21%, 19%, <1%, <1% of community‐wide GHG‐emissions for New York, Minneapolis, Delhi, and Pondicherry). Analysis of supply chains finds city average distance (food‐miles) varies (Delhi 420; Pondicherry 200; United States average 1,640 km/t‐food) and the sensitivity of GHG emissions of food demand to spatial variability of energy intensity of irrigation is greater in Indian than US cities. Analysis also finds greater pre‐consumer waste in India versus larger post‐consumer accumulations in the United States. Despite these differences in food system characteristics, food waste management and diet change consistently emerge as key strategies. Among diet scenarios, all vegetarian diets are not found equal in terms of environmental benefit, with the US Government's recommended vegetarian diet resulting in less benefit than other more focused targeted diet changes.     

Enzymes Catalyzing the Reversible Conversion of Fructose-6-Phosphate and Fructose-1,6-Bisphosphate in Maize (Zea mays L.) Kernels

The significance of the glycolytic and gluconeogenic conversion of fructose-6-phosphate and fructose-1,6-bisphosphate on sugar metabolism was investigated in maize (Zea mays L.) kernels. Maximum extractable activities of the pyrophosphate (PPi) dependent phosphofructokinase, fructose-1,6-bisphosphatase, and the ATP-dependent phosphofructokinase were measured in normal and four maize genotypes, which accumulate relatively more sugars and less starch, to determine how these enzymes are affected by the genetic lesions. Normal endosperm accumulated more dry matter than the high sugar/low starch genotypes, but protein contents did not differ greatly among the genotypes. Mutation of several starch biosynthetic enzymes had little impact on the activities of PPi-dependent phosphofructokinase, fructose-1,6-bisphosphatase, and ATP-dependent phosphofructokinase, despite the altered capacity of the cell to synthesize starch. The PPi-dependent phosphofructokinase appeared to be more active toward glycolysis in all genotypes studied. Activity of the PPi-dependent phosphofructokinase in shrunken (low sucrose synthase genotype) did not differ from the activity in other genotypes, suggesting that the gluconeogenic production of PPi may not be the primary role of the enzyme. As expected, shrunken kernels contained more sugars and less starch than normal kernels throughout kernel development except at the very early stages. Developmental profiles of normal kernels also showed marked changes in the PPi-dependent phosphofructokinase activity, whereas the level of ATP-dependent phosphofructokinase activity remained relatively steady during kernel development. In addition, the ATP-dependent phosphofructokinase, and not the PPi-dependent phosphofructokinase, appeared to correlate more closely with respiration rate. These findings suggest that glycolysis catalyzed by the ATP-dependent phosphofructokinase may serve primarily to support energy production, and glycolysis catalyzed by the PPi-dependent phosphofructokinase may contribute mainly to generation of biosynthetic intermediates.