Squash Method for Meiosis in Ovules

The ordinary Feulgen or acetic-lacmoid squash tech-nic following fixation in freshly made Carnoy's fluid (alcohol, 6: chloroform, 3: glacial acetic acid, 1), provides an easy and reliable method of studying meiosis in ovules. After fixation for 1 day, the material was hardened in 95% ethyl alcohol for 1-2 days and taken to water by gradual hydration. For staining by the Feulgen method, the material was hydrolyzed 8-10 minutes in 1 N HO at 58-60°C., followed by staining in decolorized leuco basic fuchsin for 2 hours. The staining was intensified by transferring the material to water. After 15-20 minutes the water was replaced by 45% acetic acid. For staining by acetic-lacmoid, the ovules after fixation, hardening and hydration were transferred to standard acetic-lacmoid stain to which was added 1 drop of 1 N HCl to every 10 drops of stain. Gentle heat was applied till the stain started to give fumes. After allowing 20 minutes at room temperature the material was transferred to fresh acetic-lacmoid. Some 6-12 ovules were mounted either in a drop of 45% acetic acid or acetic-lacmoid, depending upon the Feulgen or acetic-lacmoid staining respectively. Gentle and repeated tapping over the cover glass by a blunt needle loosened the cells of integument and nucellus and finally left the megaspore mother cells undergoing meiosis, fully exposed to view. The process was carried out under constant observation using the low power of the microscope. The desired amount of flattening was brought about by light pressure over the cover glass and gentle heating. The preparations were made permanent by dehydrating in ethyl alcohol and mounting in Euparal.     

Diarrheal and Environmental Isolates of Aeromonas spp. Produce a Toxin Similar to Shiga-Like Toxin 1

Diarrheal and environmental isolates of 39 strains of Aeromonas spp. were studied for detection of virulence factors. Although these 39 strains did not produce either heat-labile or heat-stable enterotoxins, culture filtrates of 31 strains produced cytopathic effects on Vero cells. Among these, culture filtrates of three strains of Aeromonas hydrophila and one strain of Aeromonas caviae could be neutralized by Escherichia coli O157:H7 Shiga-like toxin 1 antiserum. A single band of plasmid DNA of 2.14 kbp was isolated from these strains of Aeromonas spp. and E. coli O157:H7, which could be amplified by the polymerase chain reaction (PCR), employing oligonucleotide primers from the Shiga-like toxin 1 (SLT1) gene of E. coli O157:H7. E. coli HB 101 cells when transformed with the same plasmid showed cytopathic effects on Vero cells, which indicates that the SLT 1 homolog gene(s) of Aeromonas spp. is plasmid encoded. These results suggest that Aeromonas spp. may also produce Shiga-like toxin 1, or at least a cytotoxin with some homology with the Shiga-like toxin 1 of E. coli O157:H7.     

Decolorization,degradation and detoxification of carcinogenic sulfonated azo dye methyl orange by newly developed biofilm consortia

Metabolites of azo dyes are often carcinogenic, teratogenic, mutagenic and recalcitrant in nature. In this study, four biofilm consortia such as C1 (Vitreoscilla sp. ENSG301, Acinetobacter lwoffii ENSG302, Klebsiella pneumoniae ENSG303 and Pseudomonas fluorescens ENSG304), C2 (Escherichia coli ENSD101, Enterobacter asburiae ENSD102 and E. ludwigii ENSH201), C3 (E. asburiae ENSD102, Vitreoscilla sp. ENSG301 and Bacillus thuringiensis ENSW401), and C4 (E. coli ENSD101, E. ludwigii ENSH201 and B. thuringiensis ENSW401) were applied to degrade and detoxify methyl orange (MO), a carcinogenic, sulfonated mono azo dye, used in textile dyeing industry worldwide. The consortia of C1, C2, C3 and C4 showed 97.30, 98.75, 99.51 and 99.29% decolorization, respectively in yeast extract peptone (YEP) broth containing 200 mg L⁻¹ MO within 60 h of incubation in static condition. The optimum pH and temperature for decolorization was 7.0 and 28 °C, respectively. Some divalent metal ions including Mg²⁺, Ca²⁺, Zn²⁺ and Mn²⁺ could stimulate MO decolorization. UV–Vis spectral analysis showed that the absorption peak at 465 nm originated from the azo (N N) bond was completely disappeared within 60 h of incubation. Fourier transform infrared spectroscopy (FTIR) results also revealed that several major peaks including azo bond peak at 1602.6 cm⁻¹ are completely or partly vanished, deformed or shifted. Activities of azoreductase, NADH-DCIP reductase and laccase were significantly increased in the bacterial cells within 60 h of incubation in comparison to that of control (0 h). The chemical oxygen demand was incredibly reduced by 85.37 to 91.44% by these consortia. Accordingly, plant (wheat seed germination) and microbial (growth of the plant probiotic bacteria such as Pseudomonas cedrina ESR12 and Bacillus cereus ESD3 on biodegraded products) toxicity studies showed that biodegraded products of MO are non-toxic. Thus, all these consortia can be utilized in bioremediation of MO from wastewater for safe disposal into environment. To our knowledge, this is the first report on degradation and detoxification of MO from wastewater by bacterial biofilm consortia.     

An overview of the effects of urbanization on the quantity and quality of groundwater in South Asian megacities

One of the challenges facing megacities in South Asian developing countries in their attempts to realize so-called urban rejuvenation is groundwater conditioned by canal seepage and immense sewage loads. To understand the connection between groundwater pollutants and urbanization, numerous studies were reviewed, and data obtained from a variety of national and international organizations were analyzed. In Delhi and Dhaka, urbanization has lowered the groundwater level as a result of severe overextraction, and its dense population makes Delhi particularly vulnerable to groundwater pollution. In the coastal areas of Karachi and Mumbai, such pollution is magnified by the proximity of seawater as well as the increasing populations of these areas. Among the groundwater pollutants associated with urbanization, chlorides and nitrates are the chief anthropogenic toxins; thus, they are examined in this study. This paper concludes with policy recommendations for minimizing the impact of urbanization on groundwater.     

The impact of surfactant protein-A on ozone-induced changes in the mouse bronchoalveolar lavage proteome

Background  

Ozone is a major component of air pollution. Exposure to this powerful oxidizing agent can cause or exacerbate many lung conditions, especially those involving innate immunity. Surfactant protein-A (SP-A) plays many roles in innate immunity by participating directly in host defense as it exerts opsonin function, or indirectly via its ability to regulate alveolar macrophages and other innate immune cells. The mechanism(s) responsible for ozone-induced pathophysiology, while likely related to oxidative stress, are not well understood.     

Evaluation of Occupational Injuries among Young Workers in West Virginia

We compared workplace injuries between young (16 to 19 years of age) and adult workers using West Virginia Workers' Compensation database. All workers injured between January 1 and December 31, 1995 were included in the analysis. The industry-specific injury incidence rates between young and adults workers were significantly different with lower rates of injury in young workers in all sectors except service sector. In the service sector the young workers had significantly higher injury rates than adults (rate ratios for young workers were 2.28, 1.92, and 2.94 when compared with age groups 20-24, 25-34, and >34, respectively). Estimates of the proportional injury ratio (PIR) indicated significantly greater risk of finger (PIR 1.62) and hand (PIR 1.66) injuries and burns (PIR 3.27) and lacerations (PIR 1.69) in the young workers. The proportion of injuries occurring in the summer months was higher in the young than in the adults (35.2% vs. 27.0%), particularly in the service sector (79.6% vs. 25.9%). Higher injury rates in young workers compared to adults in the service sector may be explained by the seasonal employment of young workers in West Virginia.