Occurrence of extra-pair copulation in the tree swallow (Tachycineta bicolor)

Summary A new method to mark sperm transfer events between birds, using microspheres inserted into males' cloacae, was employed to assess the frequency of extra-pair copulation (EPC) in a population of tree swallows (Tachycineta bicolor) in Ontario, Canada, during the summer of 1988. We inserted 25 males with microspheres; spheres from 8 (32%) of these males were found in extra-pair females, from which we infer that males pursue a mixed reproductive strategy of monogamy coupled with seeking EPCs. The cloacae of 10 of 41 (24.4%) females were found to contain microspheres from non-mates. EPCs occur more frequently between neighboring birds than between non-neighbors. Only two within-pair copulations were detected with this method, suggesting that it underestimates the occurrence of all copulations, extra-pair or within-pair. Copulation watches revealed that within-pair copulations occur very frequently. We propose that frequent pair copulations are used by males to ensure their paternity in their mate's offspring. Offprint requests to: R.J. Robertson     

Microbiological characterization of the biological treatment of aircraft paint stripping wastewater

Leaching rates of the herbicide dichlorprop [(+/--2-(2,4-dichlorophenoxy)propanoic acid] and nitrate were measured together in field lysimeters containing undisturbed clay and peat soils. The purpose of the study was to investigate the leaching pattern of the two solutes in structured soils under different precipitation regimes. Spring barley (Hordeum distichum L.) was sown on each monolith and fertilized with 100 kg N ha(-1). Dichlorprop was applied at a rate of 1.6 kg active ingredient (a.i.) ha(-1). Each soil type received supplemental irrigation at two levels ('average' and 'worst-case'), giving total water inputs (irrigation and precipitation) of 664 and 749 mm year(-1), respectively. The larger water input approximately doubled the nitrate loads, from, on average, 11.6 to 21.8 kg N ha(-1) year(-1) in the clay soil and from 37.6 to 65.4 kg N ha(-1) year(-1) in the peat soil. In contrast, dichlorprop leaching was reduced by more than one order of magnitude when the water input was increased, from average amounts of 3.22 to 0.26 g a.i. ha(-1) during an S-month period in the clay and from 28.9 to 2.67 g a.i. ha(-1) in the peat. This leaching pattern of dichlorprop was explained in terms of preferential flow. The dried-out topsoil of 'average' watered monoliths may have allowed water flow in cracks, thus moving some of the herbicide rapidly through the topsoil to the subsoil. Once the compound reached the subsoil, degradation rates would be reduced and the herbicide residues would be stored for later leaching. Nitrate was presumably more evenly distributed in the soil matrix; therefore, water rapidly moving through macropores would not carry significant amounts of nitrate. In contrast, leaching would occur more evenly through the soil matrix, causing larger nitrate loads in the 'worst-case' watered monoliths. These results show that wet years may constitute a worst case scenario in terms of nitrate leaching, but not pesticide leaching, if macropore flow exerts a significant influence on leaching.     

Synthesis of polychlorinated biphenyls and their metabolites with a modified Suzuki-coupling

A modified procedure for the synthesis of polychlorinated biphenyls (PCBs) utilizing the Suzuki-coupling, a palladium-catalyzed cross-coupling reaction, is described. The coupling of (chlorinated) benzene boronic acids with bromochlorobenzenes, using Pd(dppf)(2)Cl(2) (dppf = 1,1'-bis(diphenylphosphino)ferrocene) as the catalyst and aqueous sodium carbonate as the base, gave the desired PCB congeners in moderate to good yields. Eleven PCB congeners, including environmentally important PCB congeners and metabolites, were synthesized using this modified procedure. This new catalyst Pd(dppf)(2)Cl(2) offers the advantage of being less air-sensitive and has a longer shelf life compared to Pd(PPh(4))(4). Three new (di-)methoxylated PCB congeners were synthesized using the same procedure by either coupling a chlorinated benzene boronic acid with a bromo (di-)methoxybenzene or by coupling a (di-)methoxy benzene boronic acid with a chlorinated bromobenzene. The dimethoxylated PCB congeners were readily converted into the respective dihydroxylated PCB derivatives using boron tribromide in dichloromethane. This approach offers the advantage of high selectivity and moderate to good yields compared to conventional methods such as the Cadogan reaction and allows the use of less toxic starting materials.     

Can oculocutaneous albinism be diagnosed prenatally?

A study of scalp and forearm skin biopsies from normally pigmented fetuses of gestational ages 16 to 28 weeks has indicated that prenatal diagnosis of albinism is a theoretical possibility. Pigment is not present in cells of the epidermis but can be found in hair follicles at the bulbous peg stage in the scalp only. Such hair follicles are present in the scalp as early as 16 weeks gestation. The findings indicate that prenatal diagnosis of albinism could be made on a scalp biopsy within the second trimester of pregnancy.     

Prenatal diagnosis of zellweger's syndrome by chorionic villus sampling-and a caveat

At 7·5 weeks gestation, two small chorionic villous biopsies were obtained from a woman at risk for Zellweger's cerebro-hepato-renal syndrome, and were separately established in culture. After 3 weeks, dihydroxyacetone phosphate acyltransferase (DHAP-AT) activity was measured in both cultures. The enzyme was markedly deficient in one cell strain and this was subsequently shown to have a male karyotype. However, the second culture had normal enzyme activity and a female karyotype. The pregnancy was terminated at 11·5 weeks gestation, and follow-up studies on fetal tissues confirmed a male fetus with markedly deficient DHAP-AT activity.     

δ13C of Tree-Ring Lignin as an Indirect Measure of Climate Change

High-resolution paleoclimatic data are an essential requirement for testing numerical models of climate change and the global carbon cycle. If the long tree-ring chronologies, originally established for the purpose of dendrochronology, are to be fully exploited as an indirect measure of past climatic variability, additional techniques are required to obtain this information. The determination of the δ¹³C value of tree-ring cellulose has been used successfully to reconstruct past climates. However, under both aerobic and anaerobic conditions, the polysaccharide components of vascular plants (mainly cellulose and hemicelluloses) are more prone to rapid degradation than lignin. This has serious implications for the use of carbon isotope values of tree-ring cellulose as an indirect measure of past climates. An absolutely dated ring-width chronology was established for oaks (Quercus robur L.) growing at Sandringham Park in eastern England. Carbon isotope values were determined on α-cellulose and `Klason' lignin isolated from annual latewood samples over the period AD 1895–1999. The carbon isotope values of earlywood lignin are correlated with the latewood carbon isotope values of the previous year, supporting the theory that some of the carbon utilised in earlywood synthesis is assimilated in the previous year. The high-frequency variance in the carbon isotope indices of latewood lignin and cellulose is highly correlated with combined July and August environmental variables, indicating that they were formed at similar times. There was no evidence of secondary lignification. These resultsdemonstrate that the determination of carbon isotope values of latewood lignin offers the potential to obtain unambiguous proxy climatic data covering several millennia.     

Phylogeography of the Indo-Pacific parrotfish Scarus psittacus: isolation generates distinctive peripheral populations in two oceans

Phylogenetic, phylogeographic, population genetic and coalescence analyses were combined to examine the recent evolutionary history of the widespread Indo-Pacific parrotfish, Scarus psittacus, over a geographic range spanning three marine biogeographic realms. We sequenced 164 individuals from 12 locations spanning 17,000 km, from 55oE to 143oW, using 322 base pairs of mitochondrial control region (D-loop). S. psittacus displayed high haplotype (h = 0.83–0.98), but low nucleotide (<1%) diversity. Most (>83%) genetic variation was within populations. AMOVA revealed significant partitioning and identified five geographic groups. These included one central population and four populations peripheral to the centre. The central population occupied reefs from Western Australia to Tahiti and represented the central Indo-Pacific biogeographic realm. Cocos Keeling was distinct from central and western Indo-Pacific biogeographic realms occupying a position intermediate to these. Peripheral populations (Hawaii, Marquesas) represented the eastern Indo-Pacific biogeographic realm, while Seychelles represented the western Indo-Pacific biogeographic realm. All but the central population expanded (<163 kya). Whilst all populations experienced major sea level and SST changes associated with Pleistocene glaciation cycles, the genetic structure of the central population was relatively homogenous unlike the remaining genetically distinctive populations.     

Selenium and arsenic content of agricultural soils from Bangladesh and Nepal

Arsenic (As) contamination of the available domestic drinking water from shallow aquifers to villagers in Bangladesh often exceeds the newest WHO standard of <10 µg As L^?1 and the older Bangladeshi standard of <50 µg As L^?1. An estimated 9.2 million shallow tube wells in Bangladesh deliver water to 97% of the rural population, placing an estimated 57 million people at risk for arsenicosis. The contamination of drinking water by As extends to W. Bengal, India and Nepal. The same shallow aquifers used for domestic water are also used to irrigate food crops, particularly rice. Irrigation adds As to soils and increases exposure of the population to additional As via foods consumed. Selenium (Se), an essential trace mineral found in soils, is absorbed by plants, entering the human food chain. It was suggested that a low dietary intake of Se may be contributing to the problem of human arsenicosis in Bangladesh. Dietary Se acts as a natural antidote to As by (1) accelerating As excretion, (2) sequestering As by complexation and (3) as an antioxidant component of the enzyme glutathione peroxidase that may counteract the prooxidant effects of As that contribute to arsenicosis and cancer. Analysis of 70 agricultural soil samples from Bangladesh by fluorimetry, ICP-AES and Neutron Activation Analysis showed the soils analyzed to be high in As (～33 µg g^?1) and biologically low in soluble Se (～0.02 µg g^?1). A low dietary intake of Se related to low soil content and this mineral in foods may be contributing to human arsenicosis in the Ganges–Brahmaputra delta.     

The Estuarine Component of the Us E.P.A.'S Environmental Monitoring and Assessment Program

The US Environmental Protection Agency's Office of Research and Development has initiated the Environmental Monitoring and Assessment Program (EMAP) to monitor status and trends in the condition of the nation's near coastal waters, forests, wetlands, agro-ecosystems, surface waters, deserts and rangelands. the programme is also intended to evaluate the effectiveness of Agency policies at protecting ecological resources occurring in these systems. Monitoring data collected for all ecosystems will be integrated for regional and national status and trends assessments. the near coastal component of EMAP consists of estuaries, coastal waters, and the Great Lakes. Near coastal ecosystems have been regionalized and classified, and an integrated sampling strategy has been developed. EPA and NOAA have agreed to coordinate and, to the extent possible, integrate the near coastal component of EMAP with the NOAA National Status and Trends Program. A demonstration project was conducted in estuaries of the mid-Atlantic region (Chesapeake Bay to Cape Cod) in the summer of 1990. in 1991, monitoring continued in mid-Atlantic estuaries and was initiated in estuaries of a portion of the Gulf of Mexico. Preliminary results indicate: there are no insurmountable logistical problems with sampling on a regional scale; several of the selected indicators are practical and sensitive on the regional scale; and an efficient effort in future years will provide valuable information on condition of estuarine resources at regional scales.