bluuebunny/crossref_metadata_2025 huggingface dataset:
Full‐term development of mouse eggs transplanted with male pronuclei derived from round spermatids: The effect of synchronization between male and female pronucleus on embryonic development
Authors: Jiang Man‐Xi , Lei Zi‐Li , Ouyang Ying‐Chun , Zhu Zi‐Yu , Zheng Yue‐Liang , Sun Qing‐Yuan , Chen Da‐Yuan
Published: May 2005

Pronucleus transplanted mice have been produced, but their donor male pronuclei were derived from mature sperm and were completely synchronous with female pronuclei because both male and female pronuclei came from the same fertilized oocyte. The present study firstly produced male pronuclei by introducing round spermatids into enucleated mouse oocytes, then transferred the male pronuclei into mouse oocytes at three activation stages and finally compared the effect of three kinds of oocytes on the development of reconstructed embryos. Our results indicate that, in enucleated oocytes, mouse round spermatid nuclei can transform to male pronuclei in a higher proportion, and the synchronization between male and female pronucleus does not significantly influence the early cleavage but the later and full‐term development of reconstructed embryos. Mol. Reprod. Dev. © 2005 Wiley‐Liss, Inc.
Functional challenge affects aquaporin mRNA abundance in mouse blastocysts
Authors: Offenberg Hanne , Thomsen Preben Dybdahl
Published: May 2005

The aquaporins (AQPs) are a family of channel proteins that facilitate diffusion of water across cell membranes. Three members of the AQP family have been detected in the mouse blastocyst: AQP 3 and 8 are located in the basolateral domain and AQP 9 predominantly in the apical domain of the trophoblast cells. These are believed to be involved in facilitating the accumulation of fluid into the blastocyst cavity. We have investigated the ability of mouse embryos to regulate AQP gene expression in response to different treatments expected to affect the passage of water across the trophoblast cells using real‐time PCR. In the first experiment 8‐cell embryos were allowed to develop to blastocysts in media from 300 to 400 mOsm. Blastocyst formation was unaffected by media made hyperosmolar by glycerol, whereas blastocyst formation was significantly reduced in sucrose‐based 350 and 400 mOsm media. AQP 8 mRNA levels were reduced when embryos were cultured in glycerol‐based hyperosmolar media. The mRNA levels of AQP 3, 7, 9, and 11 were not significantly affected by hyperosmolar media. In the second experiment blastocysts were punctured (0 hr) and allowed to re‐expand. AQP mRNA levels were examined after 2, 6, and 10 hr. Compared to control embryos, the expression of AQP 3, 7, and 9 were upregulated after 2 hr. Upregulation was sustained only for AQP 9 and this was sustained up to 6 and 10 hr after puncture. In the third experiment we compared expression of AQPs between in vitro cultured and in vivo developed blastocysts. We found that in vitro culture resulted in lower levels of AQP 8, 9, and 11 compared to in vivo development. These experiments show that mouse embryos are capable of regulating AQP mRNA abundances in response to environmental alterations. Mol. Reprod. Dev. © 2005 Wiley‐Liss, Inc.
Identification of the bull sperm p80 protein as a PH‐20 ortholog and its modification during the epididymal transit
Authors: Morin Guillaume , Lalancette Claudia , Sullivan Robert , Leclerc Pierre
Published: May 2005

We have identified an 80 kDa protein in ejaculated bull spermatozoa (p80) which is found in acrosomal and post‐acrosomal areas of the head. It has a hyaluronidase activity and shares homologies with PH‐20, a sperm surface glycoprotein involved in sperm–egg interaction. The aim of the present study was to characterize bull sperm p80 protein at the nucleic and amino acid levels to determine whether it is the bovine PH‐20 ortholog. The complete nucleotide sequence determined by RT‐PCR, 3′ and 5′ RACE show that bull p80, displays identity with the PH‐20 nucleotide and amino acid sequences. Messenger RNA and protein expressions determined by Northern blot and immunohistochemistry revealed that the protein is testicular (expressed in spermatocytes and spermatids). The localization of p80 on spermatozoa, determined by indirect immunofluorescence using a monoclonal antibody, shows the protein in acrosomal and post acrosomal areas of the head with an increase in the signal intensity as sperm progress through the epididymis. Post‐translational modifications of the protein were investigated during the epididymal maturation by Western blot on protein extracts from sperm collected in the caput, corpus and cauda portions of bull epididymis. Glycolysation status of sperm p80 protein on proteins from ejaculated and epididymidal sperm was investigated. Result show that the glycosylation status is modified as spermatozoa migrate through the epididymis. Hyaluronidase activity evaluated in protein extracts from spermatozoa of the three different epididymal sections revealed that the activity is higher at pH 7 than 4 and is not affected by epididymal maturation. These data strongly suggest that p80 is the bovine PH‐20. Mol. Reprod. Dev. © 2005 Wiley‐Liss, Inc.
DkkL1 (Soggy), a Dickkopf family member, localizes to the acrosome during mammalian spermatogenesis
Authors: Kohn Matthew J. , Kaneko Kotaro J. , DePamphilis Melvin L.
Published: May 2005

Dickkopf‐like 1 (DkkL1) is related to the Dickkopf gene family, a group of proteins that are characterized as secreted antagonists of Wingless (Wnt) signal transduction proteins. DkkL1 mRNA is found in preimplantation mouse embryos and in developing neural tissue, but in adults it is found primarily in the testes. In an effort to elucidate its function, the distribution of DkkL1 protein in mouse testis and mature sperm was analyzed by immuno‐histochemistry and immuno‐blotting techniques. DkkL1 first appeared in the developing spermatocytes in seminiferous tubules as early as Stage XII, coincident with the appearance of DkkL1 mRNA. Surprisingly, however, DkkL1 localized to the developing acrosome in spermatocytes and spermatids and to the acrosome in mature sperm. Furthermore, DkkL1 was N‐glycosylated in the testis, but it did not appear to be excreted, and the DkkL1 in mature sperm was no longer N‐glycosylated, suggesting that additional post‐translational modifications occurred during the final stages of spermatogenesis. These results identify a member of the Dickkopf family as a novel acrosomal protein that may be involved in acrosome assembly or function, a unique role for a secreted signaling molecule. Mol. Reprod. Dev. Published 2005 Wiley‐Liss, Inc.
Greedy approximation algorithms for directed multicuts
Authors: Kortsarts Yana , Kortsarz Guy , Nutov Zeev
Published: May 2005

The Directed Multicut (DM) problem is: given a simple directed graph G = (V, E) with positive capacities ue on the edges, and a set K ⊆ V × V of ordered pairs of nodes of G, find a minimum capacity K‐multicut; C ⊆ E is a K‐multicut if in G − C there is no (s, t)‐path for any (s, t) ⫅ K. In the uncapacitated case (UDM) the goal is to find a minimum size K‐multicut. The best approximation ratio known for DM is
$O(\min\{\sqrt{n},opt\})$
by Gupta, where n = |V|, and opt is the optimal solution value. All known nontrivial approximation algorithms for the problem solve large linear programs. We give the first combinatorial approximation algorithms for the problem. Our main result is an Õ(n2/3/opt1/3)‐approximation algorithm for UDM, which improves the $O(\min\{opt,\sqrt{n}\})$‐approximation for opt = Ω(n1/2+ϵ). Combined with the article of Gupta, we get that UDM can be approximated within better than $O(\sqrt n)$, unless $opt={\tilde \Theta}(\sqrt n)$. We also give a simple and fast O(n2/3)‐approximation algorithm for DM. © 2005 Wiley Periodicals, Inc. NETWORKS, Vol. 45(4), 214–217 2005
Changes in isotretinoin prescribing before and after implementation of the System to Manage Accutane Related Teratogenicity™ (SMART™) risk management program
Authors: Mendelsohn Aaron B. , Governale Laura , Trontell Anne , Seligman Paul
Published: May 2005

Purpose

To assess changes in isotretinoin prescribing following the implementation of the System to Manage Accutane Related Teratogenicity™ (SMART™) risk management program.

Methods

Using nationally representative commercial data resources on prescription drug dispensing patterns, surveys of office‐based physician practices, and a large, claims database from a pharmacy benefits manager (PBM), we examined the total number of isotretinoin prescriptions (new and refill), prescriber speciality, and patient characteristics (age, gender, severity of acne indication) in the year before (April 2001–March 2002) and the year following (April 2002–March 2003) implementation of the SMART™ program.

Results

In the 12‐months prior to SMART™, 1 508 000 prescriptions were dispensed for isotretinoin, declining approximately 23% to 1 160 000 prescriptions in the year following SMART™. There was little or no change in prescriber specialty, severity of acne, and patient age and gender.

Conclusion

SMART™ may have lead to a decrease in isotretinoin prescriptions. Further research is needed to determine whether the reduced number of isotretinoin prescriptions reflects appropriate use or inhibited use resulting in loss of access to the product's benefits. Copyright © 2005 John Wiley & Sons, Ltd.
Black philanthropy's past, present, and future
Authors: Carson Emmett D.
Published: May 2005

A brief look at the past and present helps inform speculation about the future of black philanthropy and how it may affect America's nonprofit sector.
Professionalism in black philanthropy: We have a chance to get it right
Authors: Stephens Charles R.
Published: May 2005

A veteran black fundraiser challenges blacks in organized philanthropy to embrace the measures of professionalism that will get the benefits of phi‐lanthropy focused on suffering and needful black communities.
The African American megachurch: Giving and receiving
Authors: Hall‐Russell Cheryl
Published: May 2005

The African American megachurch is responding to the challenges of modern society by using the tools of secular success: economic development, political clout, and social responsibility.
Philanthropy among African American donors in the New York metropolitan region: A generational analysis
Authors: Mottino Felinda , Miller Eugene D.
Published: May 2005

In‐person interviews with New York City–area donors reveal significant changes in black philanthropy and sharp differences between generations that came of age before the civil rights era and those who were born later.
Religious and secular giving, by race and ethnicity
Authors: Steinberg Richard , Wilhelm Mark
Published: May 2005

New data help to determine whether differences in philanthropic practices are due to race and ethnicity themselves or to a variety of factors that are correlated with these labels.
Government shekels and government shackles revisited: Questions for church and state
Authors: Kennedy Sheila Suess
Published: May 2005

What do the new provisions for Charitable Choice mean for faith‐based African American charitable organizations?
Promoting diversity in contemporary black philanthropy: Toward a new conceptual model
Authors: Copeland‐Carson Jacqueline
Published: May 2005

The concept of black philanthropy should be expanded to include practices derived from African diasporan cultural traditions that have had both historical and contemporary influences on American philanthropy.
Immigrant assimilation and charitable giving
Authors: Osili Una Okonkwo , Du Dan
Published: May 2005

Economic research about charitable giving among immigrant populations in the United States sheds light on charitable behaviors related to, but not often included in, discussions of black philanthropy.
Race philanthropy: Personalities, institutions, networks, and communities
Authors: Stanfield John H.
Published: May 2005

A scholar provides a firsthand account of his introduction to the history and sociology of race philanthropy.
Hopscotching in the neighborhood
Authors: Burnette Alice Green
Published: May 2005

Metaphorical lessons in fundraising show fundraisers how to raise money in the black community.
Extinction coefficient of polyolefin foams
Authors: Campo‐Arnáiz R. A. , Rodríguez‐Pérez M. A. , Calvo B. , de Saja J. A.
Published: May 2005

The extinction coefficient of a collection of polyolefin foams was investigated experimentally and theoretically. Transmittance spectra were measured with Fourier transform infrared spectroscopy (FTIR) for samples of various thicknesses and different chemical compositions, densities, colors and structural characteristics. The extinction coefficients were then calculated by applying Beer's law. The results showed that the extinction coefficient decreased with the mean cell size and that this was the main structural parameter influencing the extinction coefficient of the foams under study. The experimental results agreed well with the Glicksman model. Moreover, the total thermal conductivity was calculated in terms of the Rosseland equation with an accuracy of 5%. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1608–1617, 2005
Polymer characterization by interaction chromatography
Authors: Chang Taihyun
Published: May 2005

Liquid chromatography (LC) is a powerful tool for the characterization of synthetic polymers, that are inherently heterogeneous in molecular weight, chain architecture, chemical composition, and microstructure. Of different versions of the LC methods, size exclusion chromatography (SEC) is most commonly used for the molecular weight distribution analysis. SEC separates the polymer molecules according to the size of a polymer chain, a well‐defined function of molecular weight for linear homopolymers. The same, however, cannot be said of nonlinear polymers or copolymers. Hence, SEC is ill suited for and inefficient in separating the molecules in terms of chemical heterogeneity, such as differences in chemical composition of copolymers, tacticity, and functionality. For these purposes, another chromatographic method called interaction chromatography (IC) is found as a better tool because its separation mechanism is sensitive to the chemical nature of the molecules. The IC separation utilizes the enthalpic interactions to vary adsorption or partition of solute molecules to the stationary phase. Thus, it is used to separate polymers in terms of their chemical composition distribution or functionality. Further, the IC method has been shown to give rise to much higher resolution over SEC in separating polymers by molecular weight. We present here our recent progress in polymer characterization with this method. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1591‐1607, 2005
Crystallization analysis fractionation
Authors: Soares João B. P. , Anantawaraskul Siripon
Published: May 2005

Crystallization analysis fractionation (CRYSTAF) is an analytical technique for determining the distribution of chain crystallizabilities of semicrystalline polymers. After only approximately a decade since it was developed, CRYSTAF has become one of the most important characterization techniques in polyolefin characterization laboratories because it provides fast and crucial information required for the proper understanding of polymerization mechanisms and structure–property relationships. In the polyolefin industry, it has been established as an indispensable tool for product development and product quality monitoring. This highlight article covers basic operation procedures, applications, and theoretical aspects of polymer fractionation with CRYSTAF. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1557–1570, 2005
Confinement effects on the structure and dynamics of polymer systems from the mesoscale to the nanoscale
Authors: Barnes M. D. , Mehta A. , Kumar P. , Sumpter B. G. , Noid D. W.
Published: May 2005

In this article, we review some of our recent progress in experimental and simulation methods for generating, characterizing, and modeling polymer microparticles and nanoparticles in a number of polymer and polymer‐blend systems. By using instrumentation developed for probing single fluorescent molecules in micrometer‐sized liquid droplets, we have shown that polymer particles of nearly arbitrary size and composition can be made with a size dispersion that is ultimately limited by the chain length and number distribution within the droplets. Depending on the timescale for solvent evaporation—a tunable parameter in our experiments—the phase separation of otherwise immiscible polymers can be avoided by confinement effects, and homogeneous polymer‐blend microparticles or nanoparticles can be produced. These particles have tunable properties that can be controlled by the simple adjustment of the size of the particle or the relative mass fractions of the polymer components in solution. Physical, optical, and mechanical properties of a variety of microparticles and nanoparticles, differing in size and composition, have been examined with extensive classical molecular dynamics calculations in conjunction with experiments to gain deeper insights into the fundamental nature of their structure, dynamics, and properties. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1571‐1590, 2005
Boiler and combustion safety: What you don't know can kill you!
Authors: Puskar John R.
Published: May 2005

Between 1993 and 2003, industrial plant explosions claimed 34 lives and caused numerous injuries in the United States alone, according to the National Board of Boiler and Pressure Vessel Inspectors. Equipment, other than boilers, such as paint ovens, hot water heaters, process air heaters, and heat treat equipment not operated or maintained properly have also caused their share of major death, injuries and devastation. Many of these tragedies could have been prevented with proper fuel system and combustion equipment safety precautions. Some of these have devastated industry with well‐publicized incidents.

This article will discuss protections that are built into combustion equipment used within industry today. It will also discuss gross misconceptions that most owners and users have about the safety of these systems and how well they are protected. This will include a look at some of the groups involved in the design and annual review of this equipment and how even with these checks and balances equipment can be in a hazardous condition. Finally, elements of a comprehensive fuel and combustion equipment safety program are discussed. © 2005 American Institute of Chemical Engineers Process Saf Prog, 2005
Spin polarization and electronic structure of ferromagnetic Mn5Ge3 epilayers
Authors: Panguluri R. P. , Zeng Changgan , Weitering H. H. , Sullivan J. M. , Erwin S. C. , Nadgorny B.
Published: May 2005

Germanium‐based alloys hold great promise for future spintronics applications, due to their potential for integration with conventional Si‐based electronics. High‐quality single phase Mn5Ge3(0001) films, grown by solid‐phase epitaxy on Ge(111) and GaAs(111), exhibit strong ferromagnetism up to the Curie temperature TC ∼ 296 K. Point Contact Andreev Reflection (PCAR) measurements on Mn5Ge3 epilayers reveal a spin‐polarization P = 42 ± 5% for both substrates. We also calculate the spin polarization of bulk Mn5Ge3 in the diffusive and ballistic regimes using density‐functional theory (DFT). The measured spin polarization exceeds the theoretical estimates of PDFT = 35 ± 5% and 10 ± 5% for the diffusive and ballistic limits, respectively. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Ab initio density functional study of MgO (001) surface with topological defects
Authors: Licona R. , Rivas‐Silva J. F.
Published: May 2005

Magnesium oxide (MgO) is a useful material because of its catalytical properties. Moreover, surface defects have been found to play a crucial role in determining the activity and selectivity of catalytic surfaces. We present the results of a theoretical investigation of the electronic structure of the MgO (001) surface with three different topological defects. Our calculations are based on density functional theory (DFT) and the pseudopotential method. Slab geometry and periodic boundary conditions have been included with occupied orbitals expanded in plane waves. We compare the obtained results of the (001) MgO clean surface with those containing topological defects. The density of states DOS is analyzed in each case, as well as the chemical nature of the atoms belonging to the defects. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Exact electronic properties in the classically forbidden region of a metal surface
Authors: Qian Zhixin , Sahni Viraht
Published: May 2005

We derive exact properties of the inhomogeneous electron gas in the asymptotic classically forbidden region at a metal–vacuum interface within the framework of local effective potential energy theory. We derive a new expression for the asymptotic structure of the Kohn–Sham density functional theory (KS‐DFT) exchange‐correlation potential energyvxc(r) in terms of the irreducible electron self‐energy. We also derive the exact asymptotic structure of the orbitals, density, the Dirac density matrix, the kinetic energy density, and KS exchange energy density. We further obtain the exact expression for the Fermi hole and demonstrate its structure in this asymptotic limit. The exchange‐correlation potential energy is derived to bevxc(z→ ∞) = −αKS,xc/z, and its exchange and correlation components to bevx(z→ ∞) = −αKS,x/zandvc(z→ ∞) = −αKS,c/z, respectively. The analytical expressions for the coefficients αKS,xcand αKS,xshow them to be dependent on the bulk‐metal Wigner–Seitz radius and the barrier height at the surface. The coefficient αKS,c= 1/4 is determined in the plasmon‐pole approximation and is independent of these metal parameters. Thus, the asymptotic structure ofvxc(z) in the vacuum region is image‐potential‐like but not the commonly accepted one of −1/4z. Furthermore, this structure depends on the properties of the metal. Additionally, an analysis of these results via quantal density functional theory (Q‐DFT) shows that both the PauliWx(z→ ∞) and lowest‐order correlation‐kineticW(z→ ∞) components of the exchange potential energyvx(z→ ∞), and the CoulombWc(z→ ∞) and higher‐order correlation‐kinetic components of the correlation potential energyvc(z→ ∞), all contribute terms ofO(1/z) to the structure. Hence correlations attributable to the Pauli exclusion principle, Coulomb repulsion, and correlation‐kinetic effects all contribute to the asymptotic structure of the effective potential energy at a metal surface. The relevance of the results derived to the theory of image states and to KS‐DFT is also discussed. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Quantum dynamics of relaxation of a pair of coupled Morse oscillators: Effects of mass and electrical asymmetries
Authors: Maji Kaushik , Bhattacharyya S. P.
Published: May 2005

A multiconfiguration time‐dependent Hartree method based recipe is used to study the role of mass and electrical asymmetry in controlling the quantum dynamics of relaxation of a locally excited OH bond in a water molecule, modeled by a pair of interacting Morse oscillators. The fast periodic energy transfer between the two equivalent OH bonds in HOH is replaced by a rather slow process when one of the H atom is replaced by a deuterium atom. Application of static electric field along the OD bond in HOD molecule is seen to either enhance or damp the relaxation rate, depending on the strength of the applied field. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Genetic diversity of the toxic cyanobacterium Microcystis in Lake Mikata
Authors: Yoshida Mitsuhiro , Yoshida Takashi , Takashima Yukari , Kondo Ryuji , Hiroishi Shingo
Published: May 2005

The aim of the present study was to clarify the bloom dynamics and community composition of hepatotoxin microcystin‐producing and non‐microcystin‐producing Microcystis genotypes in the environment. In Lake Mikata (Fukui, Japan) from April 2003 to January 2004, seasonal variation in the number of cells with microcystin (mcy) genotypes and the genetic diversity of the total population were investigated using quantitative competitive PCR and a 16S rDNA clone library, respectively. Using competitive PCR, cells with mcyA genotypes were quantified in August and October, and the ratio of the number of these mcyA genotypes to colony‐forming Microcystis cells was 0.37 and 2.37, respectively. The 16S rDNA clones obtained could be divided into 12 ribotypes: a–l. Sixty‐one Microcystis strains isolated from Lake Mikata during the sampling period were subjected to toxicity tests using HPLC and ELISA, PCR‐based detection of the mcyA gene, and sequence analysis of the 16S rDNA. All isolates could be differentiated into 11 ribotypes (a, b, d, f, h, i, and m–q). Ribotypes b, f, i, m, n, and p had at least one strain that was a microcystin producer. In natural communities ribotypes b and f accounted for 85% of the 16S rDNA clones in August, and ribotypes b and i accounted for 24% of the clones in October. Thus, in some bloom stages the presence of microcystin genotypes identified using the 16S rDNA clone library correlated with that of mcy genotypes determined using competitive PCR. © 2005 Wiley Periodicals, Inc. Environ Toxicol 20: 229–234, 2005.
Identification of potentially toxic environmental Microcystis by individual and multiple PCR amplification of specific microcystin synthetase gene regions
Authors: Ouahid Youness , Pérez‐Silva Gonzalo , Campo Francisca F. del
Published: May 2005

Reliable cyanotoxin monitoring in water reservoirs is difficult because of, among other reasons, unpredictable changes in cyanobacteria biomass, toxin production, and inadequate sampling frequency. Therefore, it would be useful to identify potentially microcystin‐producing strains of cyanobacterial populations in field samples. With this aim, we developed a methodology to distinguish microcystin‐producing from non‐producing Microcystis strains by amplifying six characteristic segments of the microcystin synthetase mcy cluster, three corresponding to the nonribosomal peptide synthetase, genes mcyA, mcyB, and mcyC, and three to the polyketide synthase, genes mcyD, mcyE, and mcyG. For this purpose five new primer sets were designed and tested using purified DNA, cultured cells, and field colonies as DNA sources. Simultaneous amplification of several genes in multipex PCR reactions was performed in this study. The results obtained showed that: (i) the expected specific amplicons were obtained with all microcystin‐producing strains but not with nonproducing strains; (ii) cells could be directly used as DNA templates, 2000 cells being a sufficient number in most cases; (iii) simultaneous amplification of several gene regions is feasible both with cultured cells and with field colonies. Our data support the idea that the presence of various mcy genes in Microcystis could be used as a criterion for ascribing potential toxigenicity to field strains, and the possibility of applying whole‐cell assays for the simultaneous amplification of various genes may contribute significantly to simplifying toxigenicity testing. © 2005 Wiley Periodicals, Inc. Environ Toxicol 20: 235–242, 2005.
Seasonal production and molecular characterization of microcystins in Oneida Lake, New York, USA
Authors: Hotto Amber , Satchwell Mike , Boyer Gregory
Published: May 2005

Oneida Lake, northeast of Syracuse, New York, in the United States, is a shallow eutrophic lake with a well‐established toxic cyanobacterial population. Samples for DNA, toxin, and phycological analyses were collected from six stations throughout the summers of 2002 (78 samples) and 2003 (95 samples). DNA was amplified by PCR using primer sets specific to the nonribosomal microcystin synthetase complex (mcyB and mcyD). PCR analysis in 2002 indicated that the microcystin genes were present in the water column from mid‐June through October, as 88% of the samples tested positive for mcyB and 79% of the samples tested positive for mcyD. In both years the onset of microcystin production was detected as early as mid‐July by the protein phosphatase inhibition assay, reaching a maximum in 2002 of 2.9 μg L−1 and in 2003 of 3.4 μg L−1. Beginning in mid‐ to late August of both years the microcystin level at all six stations was in excess of the World Health Organization (WHO) advisory level of 1.0 μg L−1. In the present study we compared microcystin occurrence and potential production at the six stations using protein phosphatase inhibition assay, high‐performance liquid chromatography, and polymerase chain reaction analyses. © 2005 Wiley Periodicals, Inc. Environ Toxicol 20: 243–248, 2005.
First report of saxitoxin in Finnish lakes and possible associated effects on human health
Authors: Rapala Jarkko , Robertson Alison , Negri Andrew P. , Berg Katri A. , Tuomi Pirjo , Lyra Christina , Erkomaa Kirsti , Lahti Kirsti , Hoppu Kalle , Lepistö Liisa
Published: May 2005

This study is the first report of saxitoxin in cyanobacterial blooms in Finland. Bloom samples (n = 50) were collected from Finnish freshwater sites during summer months of 2002 and 2003. These samples were screened for the presence of paralytic shellfish toxins (PSTs) using the Jellett rapid PSP screening test. Samples testing positive for PSTs (n = 7) were further analyzed with saxiphilin‐ and voltage‐gated sodium channel [3H]‐STX–binding radioreceptor assays and liquid chromatography using fluorescence and mass spectrometric analysis. The results indicated that saxitoxin (STX) was the only PST analogue in the samples and that it was present in high concentrations, as much as 1 mg L−1. Microscopic analysis revealed that 95%–100% of the phytoplankton in the positive samples consisted of Anabaena lemmermannii. The trophic status of lakes in which STX‐containing blooms were found varied from oligotrophic to hypertrophic. All the lakes had high nitrogen‐to‐phosphorus ratios. In some instances, samples had been collected from sites where swimmers had reported adverse health effects, and in three such cases, reported adverse health effects were associated with sites from which samples testing positive for STX had been received. Symptoms of fever, eye irritation, abdominal pains, and skin rash were reported in children aged 2–10 years after exposure to the water. These were not the adverse human symptoms typical of STX poisoning; rather, they represented acute effects often reported following recreational exposure to cyanobacterial blooms. © 2005 Wiley Periodicals, Inc. Environ Toxicol 20: 331–340, 2005
Genotoxic potential of Microcystin‐LR and nodularin in vitro in primary cultured rat hepatocytes and in vivo in rat liver
Authors: Bouaïcha Noureddine , Maatouk Imed , Plessis Marie‐José , Périn François
Published: May 2005

Microcystin‐LR (MCYST‐LR) and nodularin (NOD) are known as tumor promoters in experimental animals and so present potential health threats for humans. Although their hepatotoxic mechanisms have been very well documented, many other effects of these toxins are relatively undescribed, indeed controversial, notably those related to their genotoxicity. In the present investigation, we examined how these toxins could induce DNA damage using a combination of in vitro and in vivo approaches. We first used the 32P‐postlabeling assay to test hydrophobic adduct formation on DNA from primary cultured rat hepatocytes treated with noncytotoxic concentrations of MCYST‐LR and NOD (2 and 10 ng/mL). Analysis of the autoradiograms of DNA digests isolated from the hepatocytes did not show any hydrophobic DNA adduct formation. However, these toxins significantly decreased the amount of hydrophobic endogenous adducts, termed I compounds. We next investigated oxidative DNA damage by using the 32P‐postlabeling assay to analyze 8‐oxo‐7,8‐dihydro‐2′‐deoxyguanosine (8‐oxo‐dG) content as a biomarker of possible DNA lesions. Both MCYST‐LR and NOD significantly enhanced 8‐oxo‐dG in time‐ and dose‐dependent manner in vitro in primary cultured hepatocytes and in vivo in rat liver cells. Thus, it appears that the depletion of endogenous DNA adducts (I compounds) and/or the increase of 8‐oxo‐dG levels by MCYST‐LR and NOD could be involved in the formation of hepatic tumors during long‐term exposure to these cyanobacterial hepatotoxins. © 2005 Wiley Periodicals, Inc. Environ Toxicol 20: 341–347, 2005.
Avian vacuolar myelinopathy linked to exotic aquatic plants and a novel cyanobacterial species
Authors: Wilde Susan B. , Murphy Thomas M. , Hope Charlotte P. , Habrun Sarah K. , Kempton Jason , Birrenkott Anna , Wiley Faith , Bowerman William W. , Lewitus Alan J.
Published: May 2005

Invasions of exotic species have created environmental havoc through competition and displacement of native plants and animals. The introduction of hydrilla (Hydrilla verticillata) into the United States in the 1960s has been detrimental to navigation, power generation, water intake, and water quality (McCann et al., 1996). Our field surveys and feeding studies have now implicated exotic hydrilla and associated epiphytic cyanobacterial species as a link to avian vacuolar myelinopathy (AVM), an emerging avian disease affecting herbivorous waterbirds and their avian predators. AVM, first reported in 1994, has caused the death of at least 100 bald eagles (Haliaeetus leucocephalus) and thousands of American coots (Fulica americana) at 11 sites from Texas to North Carolina (Thomas et al., 1998; Rocke et al., 2002). Our working hypothesis is that the agent of this disease is an uncharacterized neurotoxin produced by a novel cyanobacterial epiphyte of the order Stigonematales. This undescribed species covers up to 95% of the surface area of leaves in reservoirs where bird deaths have occurred from the disease. In addition, this species is rare or not found on hydrilla collected at sites where AVM disease has not been diagnosed. Laboratory feeding trials and a sentinel bird study using naturally occurring blooms of cyanobacteria on hydrilla leaves and farm‐raised mallard ducks (Anas platyrhynchos) induced the disease experimentally. Since 1994 AVM has been diagnosed in additional sites from Texas to North Carolina. Specific site characteristics that produce the disjunct distribution of AVM are unknown, but it is probable that the incidence of this disease will increase with the introduction of hydrilla and associated cyanobacterial species into additional ponds, lakes, and reservoirs. © 2005 Wiley Periodicals, Inc. Environ Toxicol 20: 348–353, 2005.
Insecticidal compounds of the biofilm‐forming cyanobacterium Fischerella sp. (ATCC 43239)
Authors: Becher Paul G. , Jüttner Friedrich
Published: May 2005

Cyanobacterial biofilms are grazed by many different benthic invertebrates. In particular, larvae of insects are often present in great numbers and exert strong grazing pressure on cyanobacteria. Along with morphological adaptations, allelochemicals may have been developed as defense mechanisms against insect larvae. To investigate the chemical defense of biofilm‐forming cyanobacteria, larvae of Chironomus sp., a widely distributed genus in this habitat, were used. Ten artificial biofilms of axenic and nonaxenic cyanobacteria were screened for insecticidal activity against Chironomus sp. Fischerella 43239 was the cyanobacterium that exhibited the highest acute toxicity. A bioassay‐guided isolation procedure was used to study the compounds responsible for toxicity in more detail. A toxic fraction was obtained when the 60% methanolic extract of Fischerella 43239 was separated on a C18 HPLC column. Electrospray mass spectrometry indicated the presence of several compounds in this fraction. The successful separation into individual compounds was achieved by HPLC on a cyanopropyl column. The heavily clustered quasimolecular ions observed on an electrospray mass spectrometer and the absorption spectra of the separated compounds were indicative of indole derivatives. The existence in the benthic cyanobacterium Fischerella 43239 of strong insecticidal metabolites that serve as chemical protection agents against insect larvae is supported by the data. © 2005 Wiley Periodicals, Inc. Environ Toxicol 20: 363–372, 2005.
Quantitative LC‐ESI‐MS analyses of microcystins and nodularin‐R in animal tissue—Matrix effects and method validation
Authors: Karlsson Krister M. , Spoof Lisa E. M. , Meriluoto Jussi A. O.
Published: May 2005

The matrix effects and signal response in LC‐MS analysis of six microcystins and nodularin‐R were studied in mussels and liver samples from the common eider and rainbow trout. The instrumentation used in the study was a triple quadrupole MS with electrospray ionization. The results from the spiked tissue samples showed that both signal suppression and enhancement occurred. The recorded matrix effects were not severe; all studied toxins could be detected with sufficient limit of detection in all matrices. The results indicate, however, that matrix effects must be monitored for accurate quantification of microcystin and nodularin in tissue samples. Matrix effects can be studied with standard additions in the studied matrix, as was done in this study. Solid‐phase extraction (SPE) resulted in a lower limit of detection compared to no cleanup in the sample preparation. SPE also prolonged the chromatographic stability. SPE cleanup is therefore strongly recommeded. Also described in this article are the chromatographic and mass spectrometric details of glutathione and cysteine conjugates, which are the detoxification products of the toxins. LC‐MS analysis is suitable for detoxification studies of microcystins and nodularins. Cysteine conjugate was identified as the main detoxification product in a mussel sample that was exposed to toxic cyanobacteria in an aquarium. © 2005 Wiley Periodicals, Inc. Environ Toxicol 20: 381–389, 2005.
Pressurized liquid extraction of toxins from cyanobacterial cells
Authors: Aranda‐Rodriguez Rocio , Tillmanns Angeline , Benoit Frank M. , Pick Frances R. , Harvie Jeromy , Solenaia Lioudmila
Published: May 2005

The suitability of pressurized liquid extraction (PLE) of cyanotoxins from cells was investigated. The stability of cyanotoxins (MCYST‐RR, MCYST‐LR, and anatoxin‐a) was evaluated at nine combinations of pressure and temperature (7, 10, and 14 MPa and 60°C, 80°C and 100°C) using 75% (v/v) methanol in water (MeOH) as solvent. Additional experiments investigated the stability of cyanotoxins when water was used as solvent (at a pressure of 14 MPa and a temperature of 40°C, 50°C, 60°C, 80°C, or 100°C). Results using 75% MeOH showed that the MCYST‐RR and MCYST‐LR were stable under the tested pressures up to 80°C. At 100°C MCYST recovery decreased by 10% to 17%. When water was used as the solvent, no differences in recovery were observed for MCYST‐LR, whereas for MCYST‐RR, maximum recovery was obtained at 60°C, and degradation occurred at 100°C. In contrast, anatoxin‐a was labile under all experimental conditions; the best recoveries (ca. 50%) were obtained at 60°C at the three pressures using 75% MeOH. However, only 17%–23% recovery was obtained with water extraction at all temperatures. The extraction of MCYST‐LR and variants from cells (Microcystis aeruginosa, UTCC299) was studied using two solvents, 75% MeOH and 100% water, at 14 MPa and 60°C and 100°C. PLE extracts were compared with extracts obtained with 75% MeOH and ultrasonication. Complete extraction was achieved in both solvents in one 5‐min cycle (at 100°C). Although lower recovery was obtained using PLE (79%–105%), shorter extraction time and automation are advantageous over ultrasonication. © 2005 Wiley Periodicals, Inc. Environ Toxicol 20: 390–396, 2005.
Spatial distribution and temporal variation of Microcystis species composition and microcystin concentration in Lake Biwa
Authors: Ozawa Kazuhiko , Fujioka Hiroki , Muranaka Minoru , Yokoyama Atsushi , Katagami Yukimi , Homma Takamitsu , Ishikawa Kanako , Tsujimura Shigeo , Kumagai Michio , Watanabe Mariyo F. , Park Ho‐Dong
Published: May 2005

Spatial and temporal variation in Microcystis species composition and microcystin concentration, quantified by enzyme‐linked immunosorbent assay and high‐performance liquid chromatography, were investigated during a 3‐year period (1998–2000) in the Northern Basin of Lake Biwa. The Northern Basin generally had a concentration of 5 μg L−1 or less, except at station 1 (Nagahama Bay) from July to October during the study period. The maximum concentration at station 1 was 22.7, 35.9, and 22.0 μg L−1 in October of 1998, 1999, and 2000, respectively. Eleven species of cyanobacteria were observed: Microcystis aeruginosa, M. ichthyoblabe, M. novacekii, M. wesenbergii, Oscillatoria raciborskii, Anabaena oumiana, A. affinis, A. flos‐aquae, A. ucrainica, A. smithii, and A. crassa. Of these, M. aeruginosa and M. wesenbergii were the main components observed. A high concentration of microcystin in the lake water was mostly a result of variation in the relative amount of toxic M. aeruginosa rather than of the total Microcystis cell number. This was supported by the analytical results for isolated strains. Microcystis spp. cell density in the Northern Basin appeared to increase gradually over the course of the study. This is the first study to have surveyed the Northern Basin of Lake Biwa, which supplies drinking water to 14 million people and is the largest lake in Japan. © 2005 Wiley Periodicals, Inc. Environ Toxicol 20: 270–276, 2005.
Organ distribution and bioaccumulation of microcystins in freshwater fish at different trophic levels from the eutrophic Lake Chaohu, China
Authors: Xie Liqiang , Xie Ping , Guo Longgen , Li Li , Miyabara Yuichi , Park Ho‐Dong
Published: May 2005

This article reports the organ distribution and bioaccumulation of hepatotoxic microcystins (MCs) in freshwater fishes at different trophic levels from the large, shallow, eutrophic Lake Chaohu in September 2003, when there were heavy surface blooms of toxic cyanobacteria. Among all fish, intestines and blood had the highest average content of MC‐RR + MC‐LR (22.0 and 14.5 μg g−1 DW, respectively), followed by liver, bile, and kidney (7.77, 6.32, and 5.81 μg g−1 DW, respectively), whereas muscle had the least (1.81 μg g−1 DW). MC content in muscle was highest in carnivorous fish (Culter ilishaeformis, 2.22 μg g−1 DW) and omnivorous fish (Carassius auratus, 1.96 μg g−1 DW) and was lowest in phytoplanktivorous fish (Hypophthalmichthys molitrix, 1.65 μg g−1 DW) and herbivorous fish (Parabramis pekinensis 0.660 μg g−1 DW). However, the amount of MC in the gut of H. molitrix (137 μg g−1 DW) was more than 20 times that in the other fish (<6.50 μg g−1 DW). The MCs showed a tendency to accumulate up the food chain, and piscivorous fish at the top of the food chain were at high risk of exposure to MCs in Lake Chaohu. Our study is the first to report MC concentrations in the bile and blood of wild fish. One hundred grams of fish muscle would contain 2.64–49.7 μg of MC‐LR equivalent, or about 1.3–25 times the recommended tolerable daily intake of MC‐LR by humans, indicating that fish are already severely contaminated by MCs and that the local authorities should warn the public of the risk of poisoning by eating the contaminated fish. © 2005 Wiley Periodicals, Inc. Environ Toxicol 20: 293–300, 2005.
Activity and substrate specificity of cytosolic and microsomal glutathione S‐transferase in Australian black tiger prawns (Penaeus monodon) after exposure to cyanobacterial toxins
Authors: Pflugmacher Stephan , Wiegand Claudia , Werner Stephanie , Schröder Helge , Kankaanpää Harri
Published: May 2005

Cyanobacterial toxins have been shown to have a far‐reaching impact—from aquatic organisms to human health. Aquatic organisms are typically exposed in their natural environment to toxic cyanobacteria, and exposure can occur via ingestion of cyanobacterial cells or by bioaccumulation of water‐borne toxin. The aquaculture and fisheries of crustaceans are among the most important seafood industries. Concomitant with the growth of this industry, the importance of the health of crustaceans increased. The black tiger prawn is the major cultivated prawn in Australia. The aquaculture of these prawns takes place in shallow ponds, where blooms, often of cyanobacteria, develop. Cyanobacterial toxins were hypothesized to contribute to the mortality of prawns. Many aquatic organisms have the possibility of detoxifying cyanobacterial toxins via conjugation to glutathione. The presence of several classes of the cytosolic glutathione S‐transferase system in black tiger prawns—mu, pi, theta, alpha, and tau—was shown using different substrates for measurement. Injection experiments with microcystin‐LR and feeding experiments with nodularin revealed elevation of GST activity in different types of prawn tissue in parallel with reduction in the GST classes. Correlation analyses of toxin content of the prawns with GST activity showed that low toxin content was correlated with high elevation of enzymes and high toxin content with low elevation of enzymes. © 2005 Wiley Periodicals, Inc. Environ Toxicol 20: 301–307, 2005.
Microcystin‐RR uptake and its effects on the growth of submerged macrophyte Vallisneria natans (lour.) hara
Authors: Yin Liyan , Huang Jiaquan , Li Dunhai , Liu Yongding
Published: May 2005

Microcystins are hepatotoxins produced by many species of several cyanobacterial genera. Their toxic effects on animals and some terrestrial higher plants have been well studied, but their potential effects on the development of aquatic plant seedlings are not well known, and their uptake by aquatic plants is seldom reported. In our research the seeds and seedlings of the submerged macrophyte Vallisneria natans were exposed to different concentrations of microcystin‐RR, which was purified with high‐performance liquid chromatography (HPLC). The results indicated that microcystin‐RR could accumulate differentially in the roots and leaves of V. natans seedlings. Toxin accumulation in the roots and leaves was time‐ and dose‐dependent, with higher uptake detected in the roots. Growth and development detection revealed that V. natans was relatively insensitive to microcystin‐RR at concentrations ranging from 0.0001 to 0.01 mg/L. However, when the toxin concentration was more than 0.01 mg/L, both the fresh weight and the longest leaf length of seedlings were significantly reduced after a 30‐day treatment. The root and leaf numbers were significantly decreased when 10 mg/L of toxin was used. These results suggest that microcystin‐RR can be taken up by V. natans, which subsequently will retard its development. © 2005 Wiley Periodicals, Inc. Environ Toxicol 20: 308–313, 2005.
Second order parabolic systems, optimal regularity, and singular sets of solutions
Authors: Mingione Giuseppe , Duzaar Frank
Published: May 2005

We present a new, complete approach to the partial regularity of solutions to non-linear, second order parabolic systems of the form

u_{t}−\mathrm{div}A(x,t,u,Du) = 0.

In the first part we introduce the

A

-caloric approximation lemma, a parabolic analogue of the harmonic approximation lemma of De Giorgi [Sem. Scuola Normale Superiore Pisa (1960–1961); Lectures in Math., ETH Zürich, Birkhäuser, Basel, 1996] in the version of Simon. This allows to prove optimal partial regularity results for solutions in an elementary way, under minimal and natural assumptions. In the second part we provide estimates for the parabolic Hausdorff dimension of the singular sets of solutions; the proof makes use of parabolic fractional Sobolev spaces.

Nous présentons une nouvelle approche complète auprès de la regularité partielle des solutions des systèmes paraboliques, non-linéaires, de la deuxième ordre de la forme

u_{t}−\mathrm{div}A(x,t,u,Du) = 0.

Dans une première partie nous introduisons le lemme d'approximation

A

-calorique, un analogue parabolique du lemme d'approximation harmonique de De Giorgi [Sem. Scuola Normale Superiore Pisa (1960–1961) ; Lectures in Math., ETH Zürich, Birkhäuser, Basel, 1996] d'après la version Simon. Cela permet de prouver des résultats optimales de la regularité partielle pour des solutions d'une façon elementaire sous des hypothèses minimales et naturelles. Dans la deuxième partie nous donnons des estimations des ensembles singuliers des solutions pour la dimension parabolique de Hausdorff ; la preuve se sert des espaces paraboliques fractionnaires de Sobolev.