A comparison of mussels (Perna viridis) and semi-permeable membrane devices (SPMDs) for monitoring chlorinated trace organic contaminants in Hong Kong coastal waters

A comparison of mussels (Perna viridis) and semi-permeable membrane devices (SPMDs) was carried out at five sites, representing a gradient of contaminant concentrations, in Hong Kong coastal waters. Mussels, originally collected from a “clean” location, were deployed along with SPMDs at each site for 30 days. Analyses for chlorinated pesticides and polychlorinated biphenyls (PCBs) indicated that SPMDs have potential as monitoring tools, and to some extent can overcome the problems associated with mussels, such as natural variability, differing age, sex, and physical condition. However, in most cases, SPMDs failed to rank the sites in the same order as mussels in terms of contaminant concentrations. Nonetheless, in localities where mussels cannot survive – as shown at Kwun Tong in the present experiment – SPMDs may be valuable in providing an indication of potentially bio-available lipophilic pollutants.     

The impact of agricultural Best Management Practices on water quality in a North German lowland catchment

Research on water quality degradation caused by point and diffuse source pollution plays an important role in protecting the environment sustainably. Implementation of Best Management Practices (BMPs) is a conventional approach for controlling and mitigating pollution from diffuse sources. The objectives of this study were to assess the long-term impact of point and diffuse source pollution on sediment and nutrient load in a lowland catchment using the ecohydrological model Soil and Water Assessment Tool (SWAT) and to evaluate the cost and effectiveness of BMPs for water quality improvement in the entire catchment. The study area, Kielstau catchment, is located in the North German lowlands. The water quality is not only influenced by the predominating agricultural land use in the catchment as cropland and pasture, but also by six municipal wastewater treatment plants. Diffuse entries as well as punctual entries from the wastewater treatment plants are implemented in the model set-up. Results from model simulations indicated that the SWAT model performed satisfactorily in simulating flow, sediment, and nutrient load in a daily time step. Two approaches to structural and nonstructural BMPs have been recommended in relation to cost and effectiveness of BMPs in this study. These BMPs include extensive land use management, grazing management practice, field buffer strip, and nutrient management plan. The results showed that BMPs would reduce fairly the average annual load for nitrate and total nitrogen by 8.6% to 20.5%. However, the implementation of BMPs does not have much impact on reduction in the average annual load of sediment and total phosphorus at the main catchment outlet. The results obtained by implementing those BMPs ranged from 0.8% to 4.9% and from 1.1% to 5.3% for sediment and total phosphorus load reduction, respectively. This study also reveals that reduction only in one type of BMP did not achieve the target value for water quality according to the European Water Framework Directive. The combination of BMPs improved considerably water quality in the Kielstau catchment, achieving a 53.9% and a 46.7% load reduction in nitrate and total nitrogen load, respectively, with annual implementation cost of 93,000 Euro.     

Effects of 4-methylbenzylidene camphor (4-MBC) on neuronal and muscular development in zebrafish (<Emphasis Type="Italic">Danio rerio</Emphasis>) embryos

The negative effects of overexposure to ultraviolet (UV) radiation in humans, including sunburn and light-induced cellular injury, are of increasing public concern. 4-Methylbenzylidene camphor (4-MBC), an organic chemical UV filter, is an active ingredient in sunscreen products. To date, little information is available about its neurotoxicity during early vertebrate development. Zebrafish embryos were exposed to various concentrations of 4-MBC in embryo medium for 3 days. In this study, a high concentration of 4-MBC, which is not being expected at the current environmental concentrations in the environment, was used for the purpose of phenotypic screening. Embryos exposed to 15 μM of 4-MBC displayed abnormal axial curvature and exhibited impaired motility. Exposure effects were found to be greatest during the segmentation period, when somite formation and innervation occur. Immunostaining of the muscle and axon markers F59, znp1, and zn5 revealed that 4-MBC exposure leads to a disorganized pattern of slow muscle fibers and axon pathfinding errors during the innervation of both primary and secondary motor neurons. Our results also showed reduction in AChE activity upon 4-MBC exposure both in vivo in the embryos (15 μM) and in vitro in mammalian Neuro-2A cells (0.1 μM), providing a possible mechanism for 4-MBC-induced muscular and neuronal defects. Taken together, our results have shown that 4-MBC is a teratogen and influences muscular and neuronal development, which may result in developmental defects.     

Free amino acids and energy metabolism in eggs and larvae of seabass, Lates calcarifer

Contents of free amino acids (FAA), protein and ammonium ions together with rates of ammonia excretion and oxygen consumption were measured in order to study the role of FAA as an energy substrate in developing eggs and larvae of seabass (Lates calcarifer) maintained in seawater (30 ppt) at 28 °C without feeding. Initially eggs contained 25.3 nmol ind⁻¹ of FAA of which 21.5 nmol was rapidly utilised by the developing eggs and larvae during the period up to 40 h post spawning (PS) when nearly all the yolk had been resorbed. During the same period, a net increase in protein content of 1.7 μg ind⁻¹ was observed, indicating that the major part of the amino acids lost from the free pool had been polymerised into body proteins. Assuming that the balance of the FAA after protein synthesis was used entirely for energy metabolism, FAA appeared to be an important energy substrate during the embryonic stages (2 to 16 h PS); after hatching, the contribution of FAA to energy metabolism was less significant. From 50 h PS until the end of the study period at 100 h PS, amino acids derived from somatic protein were used for energy metabolism. For the overall period from just after spawning up to 100 h PS, the data indicate that ca. 14% of the total aerobic energy metabolism was derived from amino acid catabolism. Received: 26 September 1997 / Accepted: 1 April 1998     

Metaphyseal chondrodysplasia McKusick type in a Chinese fetus,caused by novel compound heterozygosity 64T> A and 79G >T in RMRPgene

We present the first confirmed case by molecular analysis of a metaphyseal chondrodysplasia, McKusick type, in a 22-week fetus. Two novel compound heterozygous mutations, 64T> A and 79G > T, were found in the highly conserved regions of the RMRP gene. Twenty-two heterozygous g.1018 T> C mutations, two homozygous g.1018 T> C mutations, two heterozygous insertion mutations g.799_g.800insC and one heterozygous insertion mutation g.849_g.850insT were found among 100 normal controls. Careful radiological examination of the fetus for skeletal dysplasia allowed definitive diagnosis, proper genetic counselling and future prenatal diagnosis. Copyright © 2006 John Wiley & Sons, Ltd.     

Gender,extra‐firm mobility,and compensation attainment in the United States and Hong Kong

Using data from 739 U.S. managers and professionals and 593 Hong Kong Chinese managers and professionals we examined the moderating effects of gender on the relationship between changing employers and compensation attainment. While there were no gender‐based compensation differences early in the careers of these individuals (in 1991), large pay differences favoring men were observed in 1999 only among those who had followed an external labor market strategy. These results demonstrate that this phenomenon is not isolated to labor markets of the United States and strengthen the view that much of the observed pay differential favoring men has its origins in extra‐firm mobility, not intra‐firm gender discrimination. Copyright © 2004 John Wiley & Sons, Ltd.     

Uptake and depuration of cesium in the green mussel Perna viridis

 The accumulation and depuration of Cs in the green mussels (Perna viridis) commonly found in the subtropical and tropical waters were studied under the laboratory conditions using radiotracer techniques. Following an initial rapid sorption onto the mussel's tissues, uptake of Cs exhibited linear patterns over a short exposure time (8 h) at different ambient Cs concentrations. The concentration factor was independent of ambient Cs concentration. The calculated uptake rate and initial sorption constant of Cs were directly proportional to the ambient Cs concentration. The calculated uptake rate constant from the dissolved phase in the mussels was as low as 0.026 l g⁻¹ d⁻¹. Uptake rates of Cs in the mussels were inversely related to the ambient salinity. Uptake increased about twofold when the salinity was reduced from 33 to 15 ppt. The effect of salinity on Cs uptake was primarily due to the change in ambient K⁺ concentration. The uptake rate decreased in a power function with increasing tissue dry weight of the mussels, although the initial sorption was not related to the mussel's body size. The efflux rate constant of Cs in the mussels was 0.15 to 0.18 d⁻¹, and was the highest recorded to date among different metals in marine bivalves. The efflux rate constant also decreased in a power function with increasing tissue dry weight of mussels. A simple kinetic model predicted that the bioconcentration factor of Cs in the green mussels was 145, which was higher than measurements taken in their temperate counterparts. The bioconcentration factor also decreased in a power function with increasing tissue dry weight of mussels. Received: 27 October 1999 / Accepted: 16 June 2000     

Prenatal diagnosis of CLCN4-related neurodevelopmental disorder in fetuses with congenital brain anomalies

We report two male fetuses born to a healthy unrelated couple, with agenesis of the corpus callosum identified on detailed 20-week ultrasound scans and confirmed by in-utero MRI. Whole-genome sequencing identified a likely pathogenic missense variant in the CLCN4 gene, establishing this as the causative gene in the family. Pathogenic variants in the CLCN4 gene cause a neurodevelopmental disorder (also called Raynaud-Claes syndrome) inherited in an X-linked pattern. The disorder is characterised by developmental delay, intellectual disability, autism spectrum disorder, epilepsy, mental health conditions, and significant feeding difficulties, predominantly, but not exclusively, affecting males. This is the first report of a prenatal phenotype associated with variants in the CLCN4 gene. The diagnosis of the CLCN4-related neurodevelopmental disorder in this family allowed accurate genetic counseling and discussion of reproductive choices. This leaves uncertainty about the possibility of a postnatal neurodevelopmental phenotype in heterozygous females, which we discuss.