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Exploring perceptions and willingness to recycle wastes among small businesses in selected townships of the Gauteng province in South Africa.

Although small businesses play an important role in generating employment opportunities and local economic development, their involvement in recycling programs has not been characterized in greater detail. This study explored the perceptions and willingness of selected small businesses in Gauteng province townships to reuse or recycle some of their waste materials. This study used a quantitative research approach to explore the perceptions and willingness of selected small businesses to reuse or recycle some of the waste they generate. The results showed that the perceptions about the contribution of recycling to environmental pollution reduction among small businesses in the study differed significantly across the townships (χ2 = 6.892, p = 0.003). On the other hand, most formal businesses significantly agreed with the potential benefits of waste recycling on environmental pollution reduction (χ2 = 16.118, p = 0.003), saving landfill space (χ2 = 11.610, p = 0.003), improving environmental quality (χ2 = 10.443, p = 0.005), and providing job opportunities (χ2 = 10.263, p = 0.036). However, regardless of their formality (χ2 = 2.957, p = 0.228) or location (χ2 = 9.463, p = 0.051), there was no statistically significant variation in the recycling practices of the small businesses in this study. Moreover, businesses' willingness to use recycling facilities if they were located nearby differed across townships (0.05 > p = 0.010) but was similar despite the formality of the enterprises. In conclusion, recycling perceptions and willingness of small businesses can vary significantly depending on whether they are formal or informal and across townships. As a result, relevant educational interventions should be uniquely developed to raise awareness about the need for waste minimization through recovery, re-use, and recycling among small businesses in the Gauteng province.Implications: Small, Medium, and Micro enterprises (SMMEs) play a crucial role in local economic development in South Africa. However, research on their environmental sustainability is scarce, despite their significant impacts on natural resources and contributions to pollution. Most waste management studies have focused on households and municipalities, leaving a gap in understanding SMMEs' waste management behaviors, particularly in townships.

South Africa

In vitro reconstitution of chromatin replication recapitulates symmetric histone recycling.

Symmetric histone recycling is vital for maintaining epigenetic inheritance upon eukaryotic DNA replication. Recent genome-wide studies have uncovered key determinants of this process, but how these factors collectively support parental histone transfer remains incompletely understood. Here, we successfully reconstitute histone recycling with 24 purified proteins and analyze the products digested by Micrococcal nuclease with Repli-pore-seq, the newly developed pipeline combining nanopore sequencing and deep-learning-based classification. As a result, we identify histones symmetrically recycled as tetrasomes or hexasomes on nucleosome-favorable sequences. We also observe the discordance of the recycled position between lagging and leading strands on the GC-rich DNA sequences. Moreover, removal of Pol δ, Pol32, Dpb3/4, Ctf4, Csm3/Tof1, or Mrc1 disrupts the balance of histone recycling between the two daughter strands, whereas removal of Ctf4, Csm3/Tof1, or Mrc1 additionally alters the positions at which histones were recycled. Furthermore, addition of the lagging-strand maturation factors Fen1 and Cdc9 enhances histone recycling to the lagging strand. These findings provide critical insights into the molecular players and mechanisms underlying symmetric histone recycling.

Histones

Mutagens in a river heavily polluted with paper recycling wastes: results of field and laboratory mutagen assays.

Paper recycling industries generate considerable quantities of waterborne wastes, and thus water pollution constitutes the greatest environmental problem associated with this industrial activity [Hunt and Franklin, 1973]. Generally the impact of this water pollution is considered in terms of aesthetic blight and deterioration of water quality. We present data that document another aspect of this pollution, the environmental contamination of an aquatic ecosystem with mutagenic materials. A natural population of the fern Osmunda regalis growing in a river heavily polluted with paper recycling wastes had a high incidence of chromosome mutations. This population was monitored for four years for the frequency of two-break chromosome mutations. These mutations were postzygotic in origin and suggested the presence of mutagens in the river water. The fern population is downstream from the outfalls of a paper recycling mill, which was discharging 13.3 X 10(6) liters of untreated paper recycling waste per day. In 1977 a waste-water-treatment facility was constructed to remove the solid waste previously discharged into the river. This facility generates 69,300 kg of solid waste daily, which is taken to a landfill. Periodic samples of this solid waste were collected from the waste-treatment facility in the summer of 1978, extracted with various solvents, and the extracts tested for mutagenic activity with the Salmonella/mammalian microsome mutagenicity test [Ames et al, 1975]. A majority of the solid waste samples contained mutagenic materials, but in all cases S-9 activation was required for mutagenic activity. The samples also were assayed with the soybean mitotic crossing-over assay [Vig, 1975]. Four out of six samples were positive. These results document the presence of mutagens in the solid waste generated by a paper recycling industry and the genetic impact of these mutagens on the local biota.

Chromosome Aberrations

Glucose transport and recycling determined by means of two tracers and multicompartmental analysis.

Glucose labeled with 3H and 14C was injected into cows, and blood samples were taken from 1 to 720 min for measurement of plasma glucose concentration and the specific activities of each tracer. Experiments were done on two cows when nonlactating, lactating, and exhibiting spontaneous ketotic hypoglycemia. Three exponential terms were required to fit the data for each of the tracers in all six experiments. The data were consistent with two 3 compartment models of the glucose system proposed previously on the basis of 14C data only: compartments 1 and 2 represent the glucose pool, while compartment 3 represents derivatives and precurors of glucose. Constraint tests were applied to kinetic parameters in the models to test the hypothesis that [3H]glucose does not recycle. When the parameter representing the recycling of [3H]glucose was set to zero in either model, systematic deviations were found between the predicted and observed data. When the recycling parameters for [3H]glucose and [14C]glucose were allowed to adjust independently of one another, while all other parameters in the model were constrained to be the same for both [3H]glucose and [14C]glucose, a good fit was obtained. These findings are not consistent with the hypothesis that [3H]glucose does not recycle. Recycling of [14C]glucose or [3H]glucose was estimated in terms of the return transport rate back into the glucose pool (compartments 1 or 2) divided by the transport rate from the glucose pool to compartments 3. It was 22 to 53% of [4C]glucose in the normal cows but only 12 and 13% in the ketotic hypoglycemia cows.

Animals

Whole-genome surveillance supports hazard profiling of Escherichia coli lineages in recycled water treatment systems.

UNLABELLED: The use of treated wastewater is increasingly important for sustainable water management under a changing climate, yet conventional monitoring based on Escherichia coli enumeration provides limited insight into strain diversity and associated public health hazards. Here, we applied longitudinal whole-genome sequencing (WGS) to 180 E. coli isolates collected across the treatment continuum of a recycled water facility, from influent to final effluent. Genomic analysis revealed extensive strain-level heterogeneity, comprising 88 sequence types across eight phylogroups, with greater diversity in influent than in treated effluent. Phylogenetic comparisons with contextual Australian genomes indicated clustering with strains associated with companion animals, wild birds, humans, and livestock, suggesting multiple potential source reservoirs rather than a single dominant origin, although source contributions were not definitive. Despite a >90% reduction in total E. coli loads, isolates recovered from upstream and downstream stages exhibited broadly comparable virulence factor and antimicrobial resistance gene (ARG) profiles, suggesting that, within the cultured isolate collection, reductions in abundance exceeded shifts in genomic composition. To assess operational relevance, we prototyped a genomics-informed hazard framework integrating virulence determinants, ARGs, plasmid-associated mobility, and reuse-specific exposure context. Using this framework, 92.8% of isolates were classified as low hazard, and 7.2% as moderate hazard, with no isolates meeting criteria for high or critical hazard classifications. These findings demonstrate that genomic profiling of indicator organisms can reveal population structure and hazard heterogeneity not captured by conventional enumeration alone, and can provide a practical basis for incorporating genomic information into hazard-informed monitoring of recycled water systems. IMPORTANCE: Routine recycled water monitoring relies largely on culture-based E. coli counts, which indicate regulatory compliance but provide limited insight into strain diversity, persistence, and genomic characteristics relevant to public health. Using longitudinal whole-genome sequencing, we show that genetically distinct E. coli lineages, including isolates carrying combinations of virulence and antimicrobial resistance determinants, can persist through advanced treatment despite substantial reductions in overall E. coli loads. While most isolates were classified as low genomic hazard and no high- or critical-hazard isolates were detected, these findings demonstrate that conventional enumeration alone cannot distinguish between genetically diverse lineages with differing hazard potential in highly treated systems. By integrating genomic data into a hazard classification framework, this study demonstrates an applied approach to contextualize E. coli detections and distinguish low-risk background populations from isolates with elevated genomic hazard profiles. This work supports the use of genomic profiling of indicator organisms to improve surveillance, inform treatment performance assessment, and enable more risk-based management of recycled water systems.

Escherichia coli

Suppression of potassium-recycling in the renal medulla by short-term potassium deprivation.

Recently we proposed that potassium, like urea, normally undergoes medullary recycling from collecting tubule to the pars recta or descending limb of the juxtamedullary nephron and suggested that the extent of recycling is a function of the concentration of potassium in collecting tubule fluid. To test this hypothesis further, we fed young rats a potassium-free diet for 3 days and then prepared them for micropuncture of the left renal papilla. Compared to findings in normally fed animals, potassium deprivation caused a significant fall in plasma potassium and urinary excretion of potassium. There was a striking decrease in the fraction of filtered potassium remaining at the end of the justamedullary descending limb for 94 +/- 11% to 38 +/- 3% (P less than 0.001). The latter value is not significantly different from the fraction of filtered sodium remaining (36 +/- 4%) and suggests that net addition of potassium to the pars recta or descending limb was completely abolished. A correlation was observed between the fraction of filtered potassium remaining at the end of the descending limb and either urinary potassium excretion (P less than 0.001) or urinary potassium concentration(P less than 0.001) in the contralateral unexposed kidney. These results lend further support to the hypothesis of medullary recycling of potassium.

Animals

NAD recycling in the collagen membrane.

NAD recycling in the collagen membrane was investigated as follows: (1) Alcohol dehydrogenase and lactate dehydrogenase were co-immobilized in the collagen membrane and the rate of lactate production by immobilized enzymes was compared with that of free enzymes by using free NAD. An increased rate was observed in the case of immobilized enzyme. (2) The soluble high molecular weight derivatives of NAD (dextran-NAD) were immobilized in the collagen membrane with the two dehydrogenases and recycling of dextran-NAD in the membrane was examined. Lactate was produced by the membrane without adding free NAD. The interaction between the high molecular weight NAD derivatives and enzymes are also discussed.

Alcohol Oxidoreductases

5'-triphosphate recycles independently of acetylcholine in cholinergic synaptic vesicles.

The effect of hemicholinium-3 (HC-3) on vesicular contents in acetylcholine (ACh) and 5-triphosphate (ATP) and the vesicular incorporation of 14C-label derived from [14C]choline ,nd 3H-label derived from [3H]adenosine was investigated after low frequency stimulation (with a subsequent rest period) of the Torpedo electric organ. HC-3 (100 microM) caused an increased depletion of vesicular ACh and blocked the incorporation of 14C-label whereas contents in vesicular ATP and 3H-incorporation were identical with and without HC-3. HC-3 also blocked the recovery of electrical response of the tissue after stimulation but did not cause a change in vesicle numbers. The result suggest that synaptic vesicles continue to recycle ATP in the absence of recycling of ACh and that vesicular uptake and storage of the two components are not coupled to each other.

Acetylcholine

Mutagenicity and transformation by recycled water.

Increased use of contaminated water and long-range plans for the direct use of recycled water necessitate a careful assessment of the potential health effect on the population. Selected in vitro assays were used to evaluate the mutagenic and carcinogenic potential of a concentrated, recycled water sample. It was found that the concentrated water induced mutagenicity in hamster lung cells and cellular transformation in human embryonic lung fibroblasts. The use of in vitro analyses in conjunction with epidemiologic studies in determining the human risks of environmental carcinogens is discussed.

Animals

Fate of plasma membrane during endocytosis. II. Evidence for recycling (shuttle) of plasma membrane constituents.

Cultured rat embryo fibroblasts were first allowed to store for 24 h fluorescein-labeled goat immunoglobulins directed against rabbit immunoglobulins (F anti-R IgG), and were subsequently exposed for 24 h to [(3)H]acetylated rabbit immunoglobulins known to bind to the cell membrane either specifically (anti-plasma membrane IgG: A anti-PM IgG) or unspecifically (contol IgG: AC IgG). As a result of immunological interaction between the two antibodies (no effect was found if the cells had been preloaded with control goat FC IgG), a substantial portion of the stored F anti-R IgG was unloaded from its intracellular storage site, appearing in the medium in the form of soluble immune complexes with rabbit A IgG. Part of the unloaded F anti-R IgG also was recovered in association with the plasma membrane, but only when A anti-PM IgG was used. In addition, significant reverse translocation of AC IgG from plasma membrane to lysosomes or some related intracellular storage compartment was also observed. With A anti-PM IgG, this translocation was less marked and affecte at the same time the plasma membrane marker 5'- nucleotidase. Cells that had stored horseradish peroxidase (HRP) simultaneously with F anti-R IgG did not unload HRP when exposed to A anti-PM IgG. These results support strongly, though not unequivocally, the concept that plasma membrane patches interiorized by endocytosis are recycled, or shuttled, back to the cell surface. In the framework of this concept, recycling antibody-coated membrane is taken to serve as vehicle for the selective intracellular capture and extracellular discharge of immunologically bound F anti-R IgG. The alternative explanation of regurgitation triggered off by immune complexes is considered less likely in view of the lack of HRP unloading.

Animals

The calculation of annual limits of intake for plutonium-239 in man using a bone model which allows for plutonium burial and recycling.

Values of the annual limit of intake (ALI) for plutonium-239 in man have been calculated using committed dose equivalent limits as recommended by ICRP in Publication 26. The calculations were made using a multicompartment bone model which allows for plutonium burial and recycling in the skeleton. In one skeletal compartment, the growing surfaces of cortical bone, it is assumed that plutonium deposits are retained and are not subject to resorption or recycling. In the trabecular bone compartment plutonium is taken to be resorbed with either subsequent redeposition onto bone surfaces or retention in the bone marrow. ALIs for plutonium-239 have been calculated assuming a range of rates of bone accretion (0-32 micron yr-1), different amounts of plutonium retained in the marrow (0-60%) and a 20%, 45% or 70% deposition of plutonium in the skeleton from the blood. The calculations made using this bone model suggest that 750 Bq (20 nCi) is an appropriate ALI for the inhalation of class W and class Y plutonium compounds and that 830 kBq and 5 MBq (23 muCi and 136 muCi) are the appropriate ALIs for the ingestion of soluble and insoluble forms of plutonium respectively.

Administration, Oral

Efficiency of oxidative phosphorylation and energy dissipation by H+ ion recycling in rat-liver mitochondrial metabolizing pyruvate.

A method was developed for the calculation of metabolic fluxes through individual enzymatic reactions of pyruvate metabolism including the citric acid cycle in rat liver mitochondrial incubated at metabolic states between state 4 and state 3. This method is based on the measurement of the specific radioactivities of the products formed from [2-14C]pyruvate. With this procedure the energy balance of mitochondria incubated in the presence of [2-14C]pyruvate, ATP, bicarbonate and phosphate at different ATP/ADP ratios in the medium was calculated. The ATP/ADP ratios were maintained at a steady state with creatine kinase plus creatine as a phosphoryl acceptor. The calculations revealed that by adding increasing concentrations of creatine up to 20 mM the energy dissipated by the mitochondria decreased but showed a local maximum at 13mM creatine. Omission of bicarbonate from the medium led to a shift of this maximum. When energy dissipation was minimal the overall P/O ratio was maximal. The amount of energy dissipated was paralleled by the magnitude of the pH gradient across the inner membrane. From these results it was concluded that the recycling of H+ ions which consists of a passive leakage of H+ ions into the matrix and an active extrusion of these ions out of this compartment, is an important energy dissipating process. The H+ ion recycling is thus one of the processes which give rise to the state 4 respiration in mitochondria.

Adenosine Diphosphate

Unusual demand pacemaker arrhythmia due to partial recycling in the relative refractory period.

This report presents the electrocardiograms of a patient with a normally functioning lithium QRS-inhibited pulse generator that exhibited partial recycling with inappropriately short escape intervals. The occurrence of partial recycling was time-dependent rather than voltage-dependent, and was observed only when QRS complexes fell within the relative refractory period of the pulse generator. This resulted in a complex arrhythmia simulating pulse generator malfunction. This observation re-emphasizes the need for the physician to appreciate the technical characteristics of pulse generators to avoid the unnecessary replacement of normally functioning units.

Atrial Fibrillation

Steroid absorption and enterohepatic recycling.

A short review on steroid absorption and enterohepatic recycling in man with special emphasis on contraceptive and related steroids is presented. Some new experimental data on the intestinal metabolism of steroids is described and includes further observations on the effect of antimicrobial agents on steroid hormone metabolism. Evidence is presented that plasma levels of steroids may be influenced if the intestinal microflora is altered. Some formation of biologically active steroids, like estradiol, may occur in the intestinal tract and this may have both biological and pathological consequences and may be influenced by such factors as diet and sex. It is concluded that our knowledge of the intestinal and especially, the mucosal metabolism of steroids is scanty and further studies are needed to clarify the role of the intestine and enterohepatic circulation in determining the bioavailability of natural and synthetic steroids.

Absorption

Acetylcholine receptor degradation measured by density labeling: effects of cholinergic ligands and evidence against recycling.

The methodology of density labeling of proteins by biosynthetic incorporation of 2H, 13C, 15N-amino acids into newly synthesized polypeptide chains allows the direct measurement of the turnover rate of the acetylcholine receptor in cultured chick skeletal muscle. In this study, receptors synthesized in medium containing 2H, 13C, 15N-amino acids were resolved from 1H, 12C, 14N-receptors by velocity sedimentation in sucrose-deuterium oxide gradients, and their proportions were determined by computer analysis of the gradient profiles. The kinetics of turnover of acetylcholine receptors are identical for developing chick muscle fibers grown in medium containing 2H, 13C, 15N-amino acids or 1H, 12C, 14N-amino acids, and the high degree of substitution of normal aminoacyl residues by 2H, 13C, 15N-residues does not affect the turnover rate of the denser receptor. Comparison of the turnover rates in continuous and pulse-labeling experiments gave independent confirmation of these results. The application of a potent, essentially irreversible blocking agent, alpha-bungarotoxin, increases the median lifetime of receptors from 17 hr for the native unbound receptor to 22 hr for the alpha-bungarotoxin-receptor complex. As predicted, the total number of alpha-bungarotoxin binding sites increased in the continued presence of alpha-bungarotoxin due to extension of receptor lifetime. To determine whether other cholinergic agents affect the turnover rate of the receptor, measurements were performed on cultures grown in the presence of 10(-4) M d-tubocurare or 10(-4) M carbachol, a reversible antagonist and a reversible agonist, respectively, of the nicotinic acetylcholine receptor. The receptor degradation rates of the drug-treated cells were identical to control values. The total number of alpha-bungarotoxin binding sites was reduced by 30% in the presence of carbachol, indicating that this agent affects the rate of synthesis of the acetylcholine receptor. Data formerly interpreted as suggesting a cycling of receptor-containing plasma membrane out of and back into the sarcolemma are now understood to reflect the alteration in receptor lifetime upon complexing with alpha-bungarotoxin. The intracellular "hidden" receptor sites were found to remain inside the myotubes and thus do not signify an intracellular pool of recycling plasma membrane.

Animals

Recycling of glucose by rat hepatocytes.

1. The metabolism of glucose labeled uniformly with 14C, and in positions 2, 3 and 5 with tritium by hepatocytes from fed and fasted rats were studied. Cells were incubated with glucose as sole substrate, or with glucose and a variety of glucose precursors, and uptake or production of glucose, and the utilization of the isotopes was determined. 2. There was no uptake of glucose at concentration of up to 15 mM, and net glucose synthesis in the presence of precursors. 14C was however recovered in CO2, lactate and amino acids, and tritium in water. Considerable incorporation into glycogen from 14C and 3H-labeled glucose occurred at high (above 20 mM) glucose concentrations. 3. The yield in water always exceeded that in 14C-labeled products. The yield in 3HOH from [2-3H] glucose exceeded that from [5-3H] glucose, and the latter was greater than from [3-3H] glucose. 4. Utilization of labeled glucose does not follow Michaelis-Menten kinetics. The fractional rate of uptake of 14C and tritium-labeled glucose increases with glucose concentration with a maximum at about 15 mM and then declines. 5. The effect of numerous gluconeogenic substrates on the isotope utilization and the 3H/14C ratio in glycogen was studied. The uptake of 14C was always depressed. Addition of lactate and dihydroxyacetone has little effect on the detritiation of [2-3H] glucose, but it is depressed by other substrates. The detritiation of [3-3H]-and[5-3H]glucose is depressed in gluconeogenesis, that from [3-3H]glucose usually more than from [5-3H]glucose. In the presence of lactate detritiation of [3-3H]glucose is about half that from [5-3H]glucose. 6. Equations to calculate the phosphorylation of glucose and fructose 6-phosphate in the presence of futile cycling between glucose and glucose 6-phosphate and fructose 6-phosphate and fructose 1,6-bisphosphate were derived. 7. The estimate of glucose phosphorylation requires determination of the specific activity of glucose 6-phosphate from [2-3H]glucose. It appears that futile cycling between glucose and glucose 6-phosphate is extensive in cells with a high glycogen content, but is low in cells from starved rats and nearly absent in those from diabetic animals. 8. The estimation of the phosphorylation of fructose 6-phosphate in the presence of cycling requires knowledge of the specific activities of fructose 6-phosphate and fructose 1,6-bisphosphate from [3-3H]glucose. At present there are no adqquate data to calculate phosphorylation and recycling of fructose 6-phosphate, but under some conditions the rate may be quite high.

Amino Acids

Partial pacemaker recycling of implanted QRS-inhibited pulse generators.

In the evaluation of twenty-three patients with implanted QRS-inhibited lithium-powered pulse generators (Intermedics C-MOS-1 and ARCO L1-2D), we repeatedly observed the phenomenon of partial pacemaker recycling (PPR), in which the escape interval induced by a premature ventricular beat is shorter than the automatic interval (AI). In order to determine the sensing properties of these pulse generators, programmed chest wall stimulation (CWS) was systematically performed in all 23 patients and, in addition, intracardiac programmed ventricular stimulation (PVS) via temporary intravenous pacing catheters was performed in 9 of them. The AI of these pulse generators ranged from 820 to 860 msec and absolute refractory periods (ARP) from 220 to 330 msec. Precise correlation in determining pacemaker sensing properties could be demonstrated between CWS and PVS. The phenomenon of PPR occurred 110 to 240 msec following ARP with both CWS and PVW, and appeared to be time- rather than voltage-dependent. We conclude that: (1) CWS is a safe, simple and accurate method for studying pacemaker sensing properties, and (2) time-dependent PPR is a normal electrical feature of certain implanted QRS-inhibited lithium-powered pulse generators.

Cardiac Pacing, Artificial

Membrane recycling at the cytoproct of Tetrahymena.

Exocytosis and membrane recycling at the cytoproct (cell anus) of Tetrahymena pyriformis were studied using thin-section electron microscopy. Single cells were fixed at specific times relative to the elimination of the vacuole's contents--before elimination, at elimination, 3--5 s and 10--15 s following elimination. The closed cytoproct is distinguished from other pellicular regions by a single membrane at the cell surface which is circumscribed by an electron-opaque flange that links or welds the plasma membrane to the underlying alveolar margins. Microtubules originating in the flange pass inward where they lie over, and possibly guide, the approaching food vacuoles to the cytoproct. Food facuoles near the cytoproct are also accompanied by coats of microfilaments. These microfilaments appear to be active in the channelling and endocytosis of food vacuole membrane. Upon cytoproct opening the plasma membrane and food vacuole membrane fuse. Elimination seems to be essentially passive and is accomplished by re-engulfment of the old food vacuole membrane which is constantly associated with microfilaments. Reengulfment of all the food vacuole membrane requires 10--15 s and results in a closed cytoproct. The membrane remnants embedded in microfilaments form a cluster under the closed cytoproct. At the periphery of this cluster remnants take the shape of 70--130-nm spherical vesicles or 0.2-micrometer-long flattened vesicles.

Animals