bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of site, harvesting stage, and genotype on environmental staining in faba bean (Vicia faba L.)
Authors: Nasar-Abbas Syed M. , Plummer Julie A. , White Peter , Siddique Kadambot H. M. , D'Antuono Mario , Harris David , Dods Ken
Published: April 2008

Seed discoloration due to environmental staining in faba bean leads to poor quality and reduced market price. Environmental staining in faba bean is characterised by a dark brown, grey, or black discoloration of the seed coat at harvest. Its cause is unknown, but it does not appear to be caused by a pathogen. Environmental conditions during pod and seed formation and at maturity are thought to have a large effect on the degree of environmental staining. To test the hypothesis that seeds formed under stressful conditions will have a higher degree of staining, faba bean seeds were harvested at 2 different stages of maturity from trials located in a range of environmental conditions under a Mediterranean-type climate of south-western Australia over 2 seasons. Four faba bean varieties were studied (Fiord, Fiesta, Ascot, and Cairo). The majority of seeds had good colour but across the trials, 3–25% were stained up to an unacceptable level and this varied with location and variety. Seeds formed later in plant development (located on the upper nodes of the plant) had more staining than seeds formed earlier (located on the lower nodes). Seeds formed on small and weak plants had more staining than seeds formed on normal sized healthy plants. Fiord showed a greater amount of staining than Ascot, Fiesta, and Cairo when grown in the mild, southern environments. Early harvesting (at physiological maturity) did not reduce environmental seed staining compared with harvesting at full maturity. Chemical analysis of seed testa and cotyledons revealed that total phenolic contents of the testa and cotyledons increased with staining. An increase in Zn and Na and a decrease in K concentration in the testa were also associated with increased staining levels.
Resistance to Phytophthora medicaginis Hansen and Maxwell in wild Cicer species and its use in breeding root rot resistant chickpea (Cicer arietinum L.)
Authors: Knights E. J. , Southwell R. J. , Schwinghamer M. W. , Harden S.
Published: April 2008

Phytophthora root rot caused by Phytophthora medicaginis is a major disease of chickpea in Australia. Only partial resistance, derived from chickpea, is available in Australian cultivars. Five wild Cicer species were compared with chickpea cv. Jimbour (moderately resistant) in a field experiment. The proportions of accessions with significantly lower (P < 0.05) disease scores, where lower scores equate to higher resistance, were 9/9 for C. echinospermum, 9/21 for C. bijugum, 1/4 for C. judaicum, 1/29 for C. reticulatum, and 0/3 for C. pinnatifidum. The resistance of C. echinospermum (7/7 accessions) but not the other Cicer species was reproduced in a greenhouse test. Nine out of 30 chickpea × C. echinospermum-derived lines were as resistant as the C. echinospermum parents in a separate greenhouse experiment. C. echinospermum appears to be the best of the sources we examined for breeding chickpea cultivars resistant to P. medicaginis.
High subsoil chloride concentrations reduce soil water extraction and crop yield on Vertosols in north-eastern Australia
Authors: Dang Y. P. , Dalal R. C. , Mayer D. G. , McDonald M. , Routley R. , Schwenke G. D. , Buck S. R. , Daniells I. G. , Singh D. K. , Manning W. , Ferguson N.
Published: April 2008

Salinity, sodicity, acidity, and phytotoxic levels of chloride (Cl) in subsoils are major constraints to crop production in many soils of north-eastern Australia because they reduce the ability of crop roots to extract water and nutrients from the soil. The complex interactions and correlations among soil properties result in multi-colinearity between soil properties and crop yield that makes it difficult to determine which constraint is the major limitation. We used ridge-regression analysis to overcome colinearity to evaluate the contribution of soil factors and water supply to the variation in the yields of 5 winter crops on soils with various levels and combinations of subsoil constraints in the region. Subsoil constraints measured were soil Cl, electrical conductivity of the saturation extract (ECse), and exchangeable sodium percentage (ESP). The ridge regression procedure selected several of the variables used in a descriptive model, which included in-crop rainfall, plant-available soil water at sowing in the 0.90–1.10 m soil layer, and soil Cl in the 0.90–1.10 m soil layer, and accounted for 77–85% of the variation in the grain yields of the 5 winter crops. Inclusion of ESP of the top soil (0.0–0.10 m soil layer) marginally increased the descriptive capability of the models for bread wheat, barley and durum wheat. Subsoil Cl concentration was found to be an effective substitute for subsoil water extraction. The estimates of the critical levels of subsoil Cl for a 10% reduction in the grain yield were 492 mg cl/kg for chickpea, 662 mg Cl/kg for durum wheat, 854 mg Cl/kg for bread wheat, 980 mg Cl/kg for canola, and 1012 mg Cl/kg for barley, thus suggesting that chickpea and durum wheat were more sensitive to subsoil Cl than bread wheat, barley, and canola.
The conserved Wobble uridine tRNA thiolase Ctu1–Ctu2 is required to maintain genome integrity
Authors: Dewez Monique , Bauer Fanélie , Dieu Marc , Raes Martine , Vandenhaute Jean , Hermand Damien
Published: April 2008

Modified nucleosides close to the anticodon are important for the proper decoding of mRNA by the ribosome. Particularly, the uridine at the first anticodon position (U34) of glutamate, lysine, and glutamine tRNAs is universally thiolated (S
2
U34), which is proposed to be crucial for both restriction of wobble in the corresponding split codon box and efficient codon–anticodon interaction. Here we show that the highly conserved complex Ctu1–Ctu2 (cytosolic thiouridylase) is responsible for the 2-thiolation of cytosolic tRNAs in the nematode and fission yeast. In both species, inactivation of the complex leads to loss of thiolation on tRNAs and to a thermosensitive decrease of viability associated with marked ploidy abnormalities and aberrant development. Increased level of the corresponding tRNAs suppresses the fission yeast defects, and our data suggest that these defects could result from both misreading and frame shifting during translation. Thus, a translation defect due to unmodified tRNAs results in severe genome instability.
Probing microscopic origins of confined subdiffusion by first-passage observables
Authors: Condamin S. , Tejedor V. , Voituriez R. , Bénichou O. , Klafter J.
Published: April 2008

Subdiffusive motion of tracer particles in complex crowded environments, such as biological cells, has been shown to be widespread. This deviation from Brownian motion is usually characterized by a sublinear time dependence of the mean square displacement (MSD). However, subdiffusive behavior can stem from different microscopic scenarios that cannot be identified solely by the MSD data. In this article we present a theoretical framework that permits the analytical calculation of first-passage observables (mean first-passage times, splitting probabilities, and occupation times distributions) in disordered media in any dimensions. This analysis is applied to two representative microscopic models of subdiffusion: continuous-time random walks with heavy tailed waiting times and diffusion on fractals. Our results show that first-passage observables provide tools to unambiguously discriminate between the two possible microscopic scenarios of subdiffusion. Moreover, we suggest experiments based on first-passage observables that could help in determining the origin of subdiffusion in complex media, such as living cells, and discuss the implications of anomalous transport to reaction kinetics in cells.
Magnesium deficiency accelerates cellular senescence in cultured human fibroblasts
Authors: Killilea David W. , Ames Bruce N.
Published: April 2008

Magnesium inadequacy affects more than half of the U.S. population and is associated with increased risk for many age-related diseases, yet the underlying mechanisms are unknown. Altered cellular physiology has been demonstrated after acute exposure to severe magnesium deficiency, but few reports have addressed the consequences of long-term exposure to moderate magnesium deficiency in human cells. Therefore, IMR-90 human fibroblasts were continuously cultured in magnesium-deficient conditions to determine the long-term effects on the cells. These fibroblasts did not demonstrate differences in cellular viability or plating efficiency but did exhibit a decreased replicative lifespan in populations cultured in magnesium-deficient compared with standard media conditions, both at ambient (20% O
2
) and physiological (5% O
2
) oxygen tension. The growth rates for immortalized IMR-90 fibroblasts were not affected under the same conditions. IMR-90 fibroblast populations cultured in magnesium-deficient conditions had increased senescence-associated β-galactosidase activity and increased p16
INK4a
and p21
WAF1
protein expression compared with cultures from standard media conditions. Telomere attrition was also accelerated in cell populations from magnesium-deficient cultures. Thus, the long-term consequence of inadequate magnesium availability in human fibroblast cultures was accelerated cellular senescence, which may be a mechanism through which chronic magnesium inadequacy could promote or exacerbate age-related disease.
EBV-encoded EBNA-6 binds and targets MRS18-2 to the nucleus, resulting in the disruption of pRb-E2F1 complexes
Authors: Kashuba Elena , Yurchenko Mariya , Yenamandra Surya Pavan , Snopok Boris , Isaguliants Maria , Szekely Laszlo , Klein George
Published: April 2008

Epstein–Barr virus (EBV), like other DNA tumor viruses, induces an S-phase in the natural host cell, the human B lymphocyte. This is linked with blast transformation. It is believed that the EBV-encoded nuclear antigen 6 (EBNA-6) is involved in the regulation of cell cycle entry. However, the possible mechanism of this regulation is not approached. In our current study, we found that EBNA-6 binds to a MRPS18-2 protein, and targets it to the nucleus. We found that MRPS18-2 binds to both hypo- and hyperphosphorylated forms of Rb protein specifically. This binding targets the small pocket of pRb, which is a site of interaction with E2F1. The MRPS18-2 competes with the binding of E2F1 to pRb, thereby raising the level of free E2F1. Our experimental data suggest that EBNA-6 may play a major role in the entry of EBV infected B cells into the S phase by binding to and raising the level of nuclear MRPS18-2, protein. This would inhibit pRb binding to E2F1 competitively and lift the block preventing S-phase entry.
Unregulated smooth-muscle myosin in human intestinal neoplasia
Authors: Alhopuro Pia , Phichith Denis , Tuupanen Sari , Sammalkorpi Heli , Nybondas Miranda , Saharinen Juha , Robinson James P. , Yang Zhaohui , Chen Li-Qiong , Orntoft Torben , Mecklin Jukka-Pekka , Järvinen Heikki , Eng Charis , Moeslein Gabriela , Shibata Darryl , Houlston Richard S. , Lucassen Anneke , Tomlinson Ian P. M. , Launonen Virpi , Ristimäki Ari , Arango Diego , Karhu Auli , Sweeney H. Lee , Aaltonen Lauri A.
Published: April 2008

A recent study described a recessive ATPase activating germ-line mutation in
smooth-muscle myosin
(
smmhc
/
myh11
) underlying the zebrafish
meltdown
(
mlt
) phenotype. The
mlt
zebrafish develops intestinal abnormalities reminiscent of human Peutz–Jeghers syndrome (PJS) and juvenile polyposis (JP). To examine the role of
MYH11
in human intestinal neoplasia, we searched for
MYH11
mutations in patients with colorectal cancer (CRC), PJS and JP. We found somatic protein-elongating frameshift mutations in 55% of CRCs displaying microsatellite instability and in the germ-line of one individual with PJS. Additionally, two somatic missense mutations were found in one microsatellite stable CRC. These two missense mutations, R501L and K1044N, and the frameshift mutations were functionally evaluated. All mutations resulted in unregulated molecules displaying constitutive motor activity, similar to the mutant myosin underlying
mlt
. Thus,
MYH11
mutations appear to contribute also to human intestinal neoplasia. Unregulated MYH11 may affect the cellular energy balance or disturb cell lineage decisions in tumor progenitor cells. These data challenge our view on MYH11 as a passive differentiation marker functioning in muscle contraction and add to our understanding of intestinal neoplasia.
TFIID component TAF7 functionally interacts with both TFIIH and P-TEFb
Authors: Gegonne Anne , Weissman Jocelyn D. , Lu Hanxin , Zhou Meisheng , Dasgupta Arindam , Ribble Robert , Brady John N. , Singer Dinah S.
Published: April 2008

Transcription consists of a series of highly regulated steps: assembly of the preinitiation complex (PIC) at the promoter, initiation, elongation, and termination. PIC assembly is nucleated by TFIID, a complex composed of the TATA-binding protein (TBP) and a series of TBP-associated factors (TAFs). One component, TAF7, is incorporated in the PIC through its interaction with TFIID but is released from TFIID upon transcription initiation. We now report that TAF7 interacts with the transcription factors, TFIIH and P-TEFb, resulting in the inhibition of their Pol II CTD kinase activities. Importantly, in
in vitro
transcription reactions, TAF7 inhibits steps after PIC assembly and formation of the first phosphodiester bonds. Further,
in vivo
TAF7 coelongates with P-TEFb and Pol II downstream of the promoter. We propose a model in which TAF7 contributes to the regulation of the transition from PIC assembly to initiation and elongation.
Research‐ and Community‐Based Clinicians' Attitudes on Treatment Manuals
Authors: Barry Declan T. , Fulgieri Melissa D. , Lavery Meaghan E. , Chawarski Marek C. , Najavits Lisa M. , Schottenfeld Richard S. , Pantalon Michael V.
Published: April 2008

We assessed the attitudes of 18 research‐ and 22 community‐based substance abuse clinicians on treatment manuals. Research and community clinicians exhibited favorable attitudes toward manuals, and the majority (72% and 77%, respectively) reported an interest in learning more about substance use disorder (SUD) treatment manuals. Among community clinicians, greater years of experience was significantly associated with less favorable attitudes toward treatment manuals. Research clinicians endorsed significantly higher ratings for the importance attached to “theoretical rationale/overview” and “main session points to address” than community clinicians. Findings suggest that community SUD clinicians are already familiar with and have positive attitudes toward manuals, but specific subgroups have concerns that should be addressed.
Presence and Persistence of Psychotic Symptoms in Cocaine‐ versus Methamphetamine‐Dependent Participants
Authors: Mahoney James J. , Kalechstein Ari D. , De La Garza Richard , Newton Thomas F.
Published: April 2008

The primary objective of this study was to compare and contrast psychotic symptoms reported by cocaine‐ and methamphetamine‐dependent individuals. Participants included 27 cocaine‐dependent and 25 methamphetamine‐dependent males, as well as 15 cocaine‐dependent and 18 methamphetamine‐dependent females. After screening, participants were excluded if they met criteria for any Axis I diagnosis other than nicotine dependence, or methamphetamine or cocaine dependence (ie, participants had to use either methamphetamine or cocaine but were excluded if they met dependence criteria for both). The participants were administered the newly developed Psychotic Symptom Assessment Scale (PSAS), which assesses psychotic symptoms. A high proportion of both cocaine‐ and methamphetamine‐dependent men and women reported delusions of paranoia and auditory hallucinations. However, during the abstinent and intoxicated conditions, methamphetamine‐dependent men and women were more likely than cocaine‐dependent men and women to report psychotic symptoms. Future studies will compare psychotic symptoms reported by non‐dependent recreational stimulant users to stimulant‐dependent individuals.
Physical Pain and Associated Clinical Characteristics in Treatment‐Seeking Patients in Four Substance Use Disorder Treatment Modalities
Authors: Potter Jennifer Sharpe , Prather Kristi , Weiss Roger D.
Published: April 2008

Physical pain among persons seeking treatment for substance use disorders (SUD) and characteristics associated with pain were examined in a secondary analysis of data from the Drug Abuse Treatment Outcome Study (DATOS), a multi‐site treatment outcome study. Patients (N = 7,876) in four treatment modalities—long‐term residential (LTR), short‐term inpatient (STI), outpatient methadone treatment (OMT), and outpatient drug‐free (ODF)—reported severity of physical pain experienced during the preceding 12 months. Moderate to severe physical pain was reported by 21.2% of LTR patients, 26.8% of STI patients, 33.6% of OMT patients, and 17.6% of ODF patients. Individuals with and without physical pain were compared across treatment modalities. Patients with pain were more likely to report weekly heroin use [aOR = 1.73 (1.44–2.08)], weekly narcotics use [aOR = 1.43 (1.18–1.74)] and greater depressive symptoms [aOR = 1.30 (1.21–1.38)]. These findings support the presence of a sizable proportion of SUD patients with pain who may benefit from pain assessment as part of their SUD treatment.
The Color of Meth: Is It Related to Adverse Health Outcomes? An Exploratory Study in Tijuana, Mexico
Authors: Strathdee Steffanie A. , Case Patricia , Lozada Remedios , Mantsios Andrea R. , Alvelais Jorge , Pu Minya , Brouwer Kimberly C. , Miller Cari L. , Patterson Thomas L.
Published: April 2008

In a study of injection drug users (IDUs) in Tijuana, Mexico, logistic regression identified factors associated with injection of colored vs. clear methamphetamine in the prior six months (N = 613). Colors injected most often were clear (50%), white (47%), yellow (2%), and pink (1%). IDUs injecting colored meth were more likely to experience recent abscesses (34%) compared to those injecting clear meth (24%; p = 0.008), an association that persisted after adjusting for confounders. Market characteristics, possibly relating to purity or adulterants, may be associated with abscesses among methamphetamine injectors. Further study is needed to confirm and determine the mechanism of this association to better inform prevention messages.
The orthopoxvirus type I IFN binding protein is essential for virulence and an effective target for vaccination
Authors: Xu Ren-Huan , Cohen Matthew , Tang Yong , Lazear Eric , Whitbeck J. Charles , Eisenberg Roselyn J. , Cohen Gary H. , Sigal Luis J.
Published: April 2008

Nonliving antiviral vaccines traditionally target proteins expressed at the surface of the virion with the hope of inducing neutralizing antibodies. Orthopoxviruses (OPVs), such as the human smallpox virus and the mouse-equivalent ectromelia virus (ECTV; an agent of mousepox), encode immune response modifiers (IRMs) that can increase virulence by decreasing the host immune response. We show that one of these IRMs, the type I interferon (IFN) binding protein (bp) of ECTV, is essential for ECTV virulence and is a natural target of the antibody response. More strikingly, we demonstrate that immunization with recombinant type I IFN bp protects mice from lethal mousepox. Collectively, our experiments have important implications for our understanding of the role of IRMs in OPV virulence and of type I IFNs in OPV infections. Furthermore, our work provides proof of concept that effective antiviral vaccines can be made to prevent disease by targeting virulence factors as an alternative to the traditional approach that attempts to prevent infection by virus neutralization.
The exact plasma dispersion functions in the complex region
Authors: Castejon F. , Pavlov S.S.
Published: April 2008

The exact relativistic plasma dispersion functions are continued analytically into the complex plane, on the basis of a general method derived from the theory of singular Cauchy-type integrals. The main analytic properties of the dispersion functions in the complex region are studied and the physical consequences and applications of this method for ITER conditions are discussed.
Status of the new multi-frequency ECRH system for ASDEX Upgrade
Authors: Wagner D. , Grünwald G. , Leuterer F. , Manini A. , Monaco F. , Münich M. , Schütz H. , Stober J. , Zohm H. , Franke T. , Thumm M. , Gantenbein G. , Heidinger R. , Meier A. , Kasparek W. , Lechte C. , Litvak A. , Denisov G.G. , Chirkov A.V. , Tai E.M. , Popov L.G. , Nichiporenko V.O. , Myasnikov V.E. , Solyanova E.A. , Malygin S.A. , Meo F. , Woskov P.
Published: April 2008

Currently, a new multi-frequency ECRH system is under construction at the ASDEX Upgrade tokamak experiment. This system employs, for the first time in a fusion device, multi-frequency gyrotrons, step-tunable in the range 105–140 GHz. The first two gyrotrons, working at 105 and 140 GHz, were installed and tested. The matching optics unit includes a set of phase correcting mirrors for each frequency as well as a pair of broadband polarizer mirrors. The transmission line consists of non-evacuated corrugated HE11 waveguides with an inner diameter (ID) of 87 mm and has a total length of about 70 m. Transmission losses were deducted from calorimetric measurements both at the beginning and at the end of the transmission line at both frequencies and are in reasonable agreement with theory. Two transmission lines are completed so far and first plasma experiments with the new system have started. The first gyrotron Odissey-1 is currently being equipped with a broadband chemical vapour deposition (CVD) diamond Brewster output window and will become a step-tunable gyrotron with the additional frequencies 117 and 127 GHz. A tunable double-disc CVD-diamond window will be mounted at the torus. The system includes fast steerable launchers at the front end that will allow very localized feedback controlled power deposition in the plasma.
Development in Russia of high-power gyrotrons for fusion
Authors: Denisov G.G. , Litvak A.G. , Myasnikov V.E. , Tai E.M. , Zapevalov V.E.
Published: April 2008

The paper presents the latest development achievements in Russian institutions IAP/GYCOM of MW power level gyrotrons for fusion installations.
Operating experience on six 110 GHz, 1 MW gyrotrons for ECH applications
Authors: Felch K. , Blank M. , Borchard P. , Cahalan P. , Cauffman S. , Jory H. , Gorelov Y. , Lohr J.
Published: April 2008

Since 1999, CPI has shipped six, 110 GHz, 1 MW, 5 s pulsed gyrotrons to General Atomics (GA) for use in electron cyclotron heating experiments on the DIII-D tokamak. As a result of extensive testing of these gyrotrons at CPI and GA, a wealth of information has been obtained regarding the long-term performance of the original electrical and mechanical design of the tubes. All of the gyrotrons have achieved long-pulse operation and five of the six gyrotrons achieved 1 MW output power levels with the nominal beam voltage and current of 80 kV and 40 A, respectively. Experience with the electron guns and interaction cavities has been quite good, though the low efficiency experienced by one gyrotron may be attributed to a gun or cavity irregularity. The internal converters employed in the gyrotrons have produced high-quality Gaussian output beams with internal diffractions losses of 5–6.5%. After several years of operation, the first three 110 GHz gyrotrons experienced collector failures due to cyclic fatigue. Improved analyses and diagnostics have been employed to avoid these problems in the future. Two problems have been experienced with the diamond output windows. These problems have been eliminated by changing braze techniques and procedures. Based on the experience obtained on these six gyrotrons, recommendations can be made for future gyrotron development work.
Steady-state operation of 170 GHz–1 MW gyrotron for ITER
Authors: Kasugai A. , Sakamoto K. , Takahashi K. , Kajiwara K. , Kobayashi N.
Published: April 2008

A 170 GHz gyrotron has been developed at JAEA, which has achieved operation of 1 MW/800 s and up to 55% efficiency. This is the first demonstration of a gyrotron achieving and even exceeding the ITER operating requirements of 1 MW/500 s and 50% efficiency. In addition the gyrotron demonstrated operation for 1 h with an output power of 0.6 MW. The oscillation was stable with all cooling water temperatures and vacuum pressure reaching equilibrium conditions during the pulse length at either power level. The successful operation was aided by a very low level of stray radiation (∼2% of the output power), which contributed to fast conditioning and stable operation. The output power from the gyrotron was coupled into an ITER sized corrugated waveguide (ϕ = 63.5 mm) via a matching optics unit with a total of 0.97 MW transmitted to the dummy load after two miter bends and ∼7 m of a waveguide without any trouble. These results give an encouraging outlook for the success of the ITER electron cyclotron heating and current drive system.
A fast switch, combiner and narrow-band filter for high-power millimetre wave beams
Authors: Kasparek W. , Petelin M.I. , Shchegolkov D.Yu , Erckmann V. , Plaum B. , Bruschi A.
Published: April 2008

A fast directional switch (FADIS) is described, which allows controlled switching of high-power microwaves between two outputs. A possible application could be synchronous stabilization of neoclassical tearing modes (NTMs). Generally, the device can be used to share the installed EC power between different types of launchers or different applications (e.g. in ITER, midplane/upper launcher). The switching is performed electronically without moving parts by a small frequency-shift keying of the gyrotron (some tens of megahertz), and a narrow-band diplexer. The device can be operated as a beam combiner also, which offers attractive transmission perspectives in multi-megawatt ECRH systems. In addition, these diplexers are useful for plasma diagnostic systems employing high-power sources due to their filter characteristics.

The principle and the design of a four-port quasi-optical resonator diplexer is presented. Low-power measurements of switching contrast, mode purity and efficiency show good agreement with theory. Preliminary frequency modulation characteristics of gyrotrons are shown, and first results from high-power switching experiments using the ECRH system for W7-X are presented.
Presentations of finite simple groups: A quantitative approach
Authors: Guralnick R. , Kantor W. , Kassabov M. , Lubotzky A.
Published: April 2008

There is a constantC0C_0such that all nonabelian finite simple groups of ranknnoverFq\mathbb {F}_q, with the possible exception of the Ree groups2G2(32e+1)^2G_2(3^{2e+1}), have presentations with at mostC0C_0generators and relations and total length at mostC0(log⁡n+log⁡q)C_0(\log n +\log q). As a corollary, we deduce a conjecture of Holt: there is a constantCCsuch thatdim⁡H2(G,M)≤Cdim⁡M\dim H^2(G,M) \leq C\dim Mfor every finite simple groupGG, every primeppand every irreducibleFpG{\mathbb F}_p G-moduleMM.
On intervals in subgroup lattices of finite groups
Authors: Aschbacher Michael
Published: April 2008

We investigate the question of which finite lattices

L
L

are isomorphic to the lattice

[
H
,
G
]

[H,G]

of all overgroups of a subgroup

H
H

in a finite group

G
G

. We show that the structure of

G
G

is highly restricted if

[
H
,
G
]

[H,G]

is disconnected. We define the notion of a “signalizer lattice" in

H
H

and show for suitable disconnected lattices

L
L

, if

[
H
,
G
]

[H,G]

is minimal subject to being isomorphic to

L
L

or its dual, then either

G
G

is almost simple or

H
H

admits a signalizer lattice isomorphic to

L
L

or its dual. We use this theory to answer a question in functional analysis raised by Watatani.
R-Spondin Family Members Regulate the Wnt Pathway by a Common Mechanism
Authors: Kim Kyung-Ah , Wagle Marie , Tran Karolyn , Zhan Xiaoming , Dixon Melissa A. , Liu Shouchun , Gros Delphine , Korver Wouter , Yonkovich Shirlee , Tomasevic Nenad , Binnerts Minke , Abo Arie
Published: April 2008

The R-Spondin (RSpo) family of secreted proteins is implicated in the activation of the Wnt signaling pathway. Despite the high structural homology between the four members, expression patterns and phenotypes in knockout mice have demonstrated striking differences. Here we dissected and compared the molecular and cellular function of all RSpo family members. Although all four RSpo proteins activate the canonical Wnt pathway, RSpo2 and 3 are more potent than RSpo1, whereas RSpo4 is relatively inactive. All RSpo members require Wnt ligands and LRP6 for activity and amplify signaling of Wnt3A, Wnt1, and Wnt7A, suggesting that RSpo proteins are general regulators of canonical Wnt signaling. Like RSpo1, RSpo2-4 antagonize DKK1 activity by interfering with DKK1 mediated LRP6 and Kremen association. Analysis of RSpo deletion mutants indicates that the cysteine-rich furin domains are sufficient and essential for the amplification of Wnt signaling and inhibition of DKK1, suggesting that Wnt amplification by RSpo proteins may be a direct consequence of DKK1 inhibition. Together, these findings indicate that RSpo proteins modulate the Wnt pathway by a common mechanism and suggest that coexpression with specific Wnt ligands and DKK1 may determine their biological specificity in vivo.
WELFARE IN THE NASH EQUILIBRIUM IN EXPORT TAXES UNDER BERTRAND DUOPOLY
Authors: Clarke Roger , Collie David R.
Published: April 2008

In the Eaton and GrossmanQuarterly Journal of Economics, 101 (1986), pp. 383–406 model of export taxes under Bertrand duopoly, it is shown that welfare in the Nash equilibrium in export taxes is always higher than welfare under free trade for both countries.
Diet composition of the seahorses, Hippocampus guttulatus Cuvier, 1829 and Hippocampus hippocampus (L., 1758) (Teleostei, Syngnathidae) in the Aegean Sea
Authors: Kitsos M.‐S. , Tzomos Th. , Anagnostopoulou L. , Koukouras A.
Published: April 2008

The diet composition of the European seahorses, Hippocampus guttulatus and Hippocampus hippocampus was determined based on the analysis of 279 and 19 specimens, respectively, collected in the Aegean Sea. The diet of both species was mainly based on Crustacea, with Amphipoda, Anomura Decapoda and Mysidacea being the dominant prey categories. ANOSIM analyses, however, indicated statistically significant differences in the diet of the two species as well as differences in the diet composition of non‐brooding males, brooding males and females within each species. In H. guttulatus, stomach fullness percentages and vacuity coefficient values indicated that female individuals seem to have a higher feeding activity in relation to males.
Trophic interactions among native and introduced fishes in a northern Patagonian oligotrophic lake
Authors: Lattuca M. E. , Battini M. A. , Macchi P. J.
Published: April 2008

In summer the littoral zone of Lake Rivadavia contained almost all the juveniles of the native fish species present in the lake together with juveniles of the introduced salmonid Oncorhynchus mykiss. In particular, a high degree of foraging interaction was found among juveniles of the native species Aplochiton zebra and Percichthys trucha and juveniles O. mykiss. Differences in the juvenile assemblage composition, both in the presence and in the relative proportion of the species were associated with areas with different densities of vegetation. The adults of nearly all species were generalized benthic invertebrate predators. Only adults of A. zebra were absent in the littoral. Juvenile and adult O. mykiss were the only fish that preyed on planktonic organisms. Oncorhynchus mykiss was the only species that performed an ontogenetic diet shift between juveniles and adults, changing main prey categories from benthic to planktonic species.
An RNA:DNA‐based growth model for young‐of‐the‐year winter flounder Pseudopleuronectes americanus (Walbaum)
Authors: Mercaldo‐Allen R. , Kuropat C. , Caldarone E. M.
Published: April 2008

A laboratory calibration experiment was conducted to determine the relationship between nucleic acid‐based variables and growth rate in young‐of‐the‐year winter flounder Pseudopleuronectes americanus. Three temperatures and three feeding levels were used to produce a variety of growth rates. Nucleic acid analyses were conducted on white muscle tissue using an ultraviolet absorption assay. RNA concentration (μg mg−1 wet tissue mass) and the ratio of RNA:DNA (RRD) were positively correlated with a mass‐based instantaneous growth coefficient (GM) (r = 0·42 and 0·72, respectively). Fifty‐one per cent of the variability in growth rate was explained by the simple linear regression GM=−0·02615 + 0·00848RRD (P < 0·001). This model can be used to estimate recent growth rates for early juvenile winter flounder (27–52 mm standard length) at temperatures ranging from 11 to 24° C.
Species differences in courtship acoustic signals among five Lake Malawi cichlid species (Pseudotropheus spp.)
Authors: Amorim M. C. P. , Simões J. M. , Fonseca P. J. , Turner G. F.
Published: April 2008

Male courtship acoustic signals from five Lake Malawi cichlid fish species of the Pseudotropheus zebra complex were recorded and compared. Sounds made by males of P. zebra, Pseudotropheus callainos and the undescribed species known as Pseudotropheus ‘zebra gold’ from Nkhata Bay, and Pseudotropheus emmiltos and Pseudotropheus faizilberi from Mphanga Rocks, differed significantly in the number of pulses and in pulse period. The largest differences in acoustic variables were found among the sympatric Mphanga Rocks species that, in contrast to the other three species, show relatively minor differences in male colour and pattern. These findings suggest that interspecific mate recognition is mediated by multimodal signals and that the mass of different sensory channels varies among sympatric species groups. This study also showed that sound peak frequency was significantly negatively correlated with male size and that sound production rate increased significantly with courtship rate.
Temporal variation and feeding ecology of juvenile Sebastes in rocky intertidal tidepools of northern California, with emphasis on Sebastes melanops Girard
Authors: Studebaker R. S. , Mulligan T. J.
Published: April 2008

This study examined the seasonal use of rocky intertidal areas by young‐of‐the‐year (YOY) Sebastes spp. at three locations in northern California, 2003 to 2005. Six species of Sebastes were noted during the study with black rockfish Sebastes melanops comprising >99% of the total number sampled. Sebastes melanops were noted in rocky intertidal areas from May to August with peak abundances occurring in May or June. Variation in recruitment and feeding was evident among years. Diet analysis, using the index of relative importance (%IRI) and the modified index (%IM), showed that YOY S. melanops and Sebastes mystinus consumed a variety of prey items with harpacticoid copepods and gammaridean amphipods being the dominant prey categories. The rocky intertidal appears to serve as an important habitat for YOY S. melanops in northern California.
Effects of environment on electric field detection by small spotted catshark Scyliorhinus canicula (L.)
Authors: Filer J. L. , Booker C. G. , Sims D. W.
Published: April 2008

This study evaluated the influence of environment (substratum type and depth) on the electroreception capabilities of small spotted catsharks Scyliorhinus canicula in response to prey‐simulating electric fields. In experiments where electric fields (applied current 15 μA) were presented beneath different substrata (sand, pebbles, rocks and control) it was found that search effort was not different between substrata or S. canicula sexes, however, both rates of turning and biting towards active electrodes were decreased over pebbles and rocks compared with sand and the control (no substratum). There was no significant effect of sex on turn and bite rates over any substrata. Electric fields were then presented beneath different depths of sand to examine the depth‐limits of fish electroreception. Turn and bite rates were significantly lower at depths below 10 mm, with no bites towards electrodes made when they were >30 mm depth. Search effort was not found to be different between different burial depth treatments or between sexes. These results indicate substratum type and depth influences the ability of S. canicula to detect prey‐simulating electric fields. This variation in electroreceptive performance may influence space use of sharks.
The ability of gadoids to take advantage of a short‐term high availability of forage fish: the example of spawning aggregations in Barents Sea capelin
Authors: Bogetveit F. R. , Slotte A. , Johannessen A.
Published: April 2008

During 11 March to 4 April 2002, the distribution of Barents Sea capelin Mallotus villosus along the coast of Finnmark, northern Norway, was covered four times by combining acoustic survey with trawling, synoptically and simultaneously sampling capelin and its main fish predators; cod Gadus morhua, haddock Melanogrammus aeglefinus and saithe Pollachius virens. The surveys demonstrated how these gadoid predators were able to exploit such a short‐term abundance of forage fish. The predator aggregation as well as the stomach fullness and proportion of capelin in their diet followed the capelin spawning migration, increasing in areas and periods with increasing capelin abundance. Capelin clearly constituted most of the biomass in stomachs of cod (97%), haddock (87%) and saithe (96%). The stomach fullness was highest in cod and lowest in haddock, although in areas with low capelin abundance, saithe had more capelin in their stomachs. The total length (LT) of capelin in predator stomachs increased with predator LT, but the proportion of capelin in the diet was not influenced by predator LT. The capelin in predator stomachs was significantly smaller than capelin in the trawl hauls, also when compared within the same sex, indicating feeding selectivity towards weaker individuals. Female capelin, being significantly smaller than the males, predominated in the diet of haddock, whereas in cod and saithe the sex ratio was more equal. Male capelin predominated in the predator diet during the pre‐spawning period, whereas the females predominated as the spawning commenced. During the overall study period, most of the female capelin in predator stomachs was in a pre‐spawning or a spawning stage, whereas the majority of the males appeared to be spent. Regardless of sex, the percentage of spent, relative to pre‐spawning or spawning capelin in the diet of the predators, followed the capelin spawning dynamics, increasing with time as the spawning progressed.
The effect of season and sex on trophic levels of marine fishes
Authors: Karachle P. K. , Stergiou K. I.
Published: April 2008

The diet of 76 species from Greek waters (north Aegean Sea) was examined for the determination of trophic level by species, season and sex. Trophic level estimates were derived from TrophLab software based on collected stomach content data. Such estimates are important for the implementation of marine management indicators, such as the marine trophic index. The mean ±s.e. difference between minimum and maximum trophic levels among seasons within species was 0·45 ± 0·04 and for 28·8% of the species this difference was larger than the corresponding s.e. of the trophic level of the pairs of seasons examined. Depending on which seasonal trophic level (i.e. autumn, winter, spring or summer) was used for assigning a species into a functional trophic group 33·9 and 8·5% of the species changed one and more than one group, respectively. Finally, the mean ±s.e. absolute difference of male and female trophic level was 0·18 ± 0·02, and only for 6·6% of the species this difference was larger than the s.e. of trophic level for each sex separately. Depending on the trophic level used for assigning the species into a functional group (i.e. male v. female), only 6·6 and 3·2% of the species changed one and more than one groups, respectively. It is therefore clear that all measures used in this study indicated that the effect of season on trophic level estimates was higher, compared to that of sex, the latter being of minor importance to feeding studies. Hence, future effort on stomach content analysis should focus on the examination of seasonal, small to moderate sample sizes.
Apogon smithi (Kotthaus, 1970) (Teleostei: Apogonidae), a Red Sea cardinalfish colonizing the Mediterranean Sea
Authors: Golani D. , Appelbaum‐Golani B. , Gon O.
Published: April 2008

Smith’s cardinalfish Apogon smithi is recorded for the first time in the Mediterranean Sea. Six specimens were caught by commercial trawler north of Jaffa, Israel, at depths of 40 m and the relatively high number of specimens suggests that A. smithi has established a sustainable population. This is the third Indo‐Pacific apogonid species documented in the Mediterranean Sea, and is assumed to be a migrant originating from the Red Sea.
Effects of anthropogenic disturbances on the diversity and composition of the butterfly fauna of sites in the Sango Bay and Iriiri areas, Uganda: implications for conservation
Authors: Akite Perpetra
Published: April 2008

In assessing environmental change, butterflies have been proven as replicable indicators of biodiversity and functional integrity that can be monitored at a range of scales. Butterflies have been identified as important bio‐indicators for assessing biodiversity and monitoring ecosystem responses to environmental perturbations. The objectives of this study were to determine changes in the butterfly fauna of differing sites in the Sango Bay Area (SBA) and Iriiri (Karamoja) in comparison with data collected 10 years ago, and to investigate the impact of different degrees of habitat disturbance on butterflies. The general butterfly diversity was determined by trapping and sweep netting along transect lines and by random sweeping. The impact of human‐induced disturbance was assessed by comparing species richness and composition between the sites and regressing the weighted disturbances against species diversity per site. There was a marked decrease in species diversity and varied species composition between the two studies and between the habitat types. Charcoal burning and grazing had significant negative correlations with diversity within forest sites (r2 = 0.825,P < 0.05), whereas cultivation and tree cutting/logging had significant negative correlations with diversity of open savannas (r2 = 0.718,P < 0.05 andr2 = 0.999,P < 0.05, respectively).
The abundance of birds in Uganda’s inhabited areas and the importance of pastoral areas
Authors: Asasira J. , Pomeroy D.
Published: April 2008

The Uganda bird‐monitoring programme has so far generated more than 18,600 observations from the 37 sites where land birds are monitored annually. Ten of the sites are in farmed area (agroecosystems), thirteen in semi‐natural pastoral ecosystems and fourteen in natural ecosystems (mainly national parks). The farms are almost entirely small‐scale and very diverse in their land use systems. Monitoring is by Timed Species Counts from which the frequency of recording of each species at each site can be generated (with over 460 species recorded so far, the overall spread sheet contains many zero values). The species numbers overall were the highest at natural sites (375 species), which also had the highest numbers of birds that often use trees, and those which are specialist grassland or aerial species or Palearctic visitors; but numbers of Red Data species are the highest in semi‐natural sites. As one would expect, formerly forested areas and moist savannas support most tree birds, whilst Red Data species were most frequently recorded in areas of impeded drainage – typically, these are periodically flooded. Grassland specialists are more common in dry than in moist savannas. Palearctic migrants are nowhere common. Uganda’s pastoral areas, on which domestic livestock graze and browse on predominant natural vegetation, are rich in birds and deserve a much more detailed study.
The coincidence of biodiversity patterns and human settlement in Africa
Authors: Fjeldså J. , Burgess N. D.
Published: April 2008

In spite of high loss of biodiversity in landscapes converted to farmland or urban areas, a positive correlation exists between species richness and endemism and human population density at coarse spatial scales. Data representing precolonial and contemporary human population patterns in Africa were overlaid on species distribution data covering 4080 vertebrate species. Species richness tracks both the precolonial and the current human population density. Areas of high vertebrate endemism are particularly closely associated with precolonial population centres. This suggests that patterns of population growth in Africa were, more than today, governed by factors that also enhanced local species persistence and speciation. The traditional conservation focus on wilderness areas with few people, and generally rather low endemism, needs to be complemented with strategies for sustainable development in some of the densely populated areas.
Resource utilization by large migratory herbivores of the Athi‐Kapiti ecosystem
Authors: Imbahale Susan Sangilu , Githaiga John Maina , Chira Robert Mutugi , Said Mohammed Yahya
Published: April 2008

The goal of the study was to establish whether the changes in land use affect resource utilization by large migratory herbivores in the Athi‐Kapiti ecosystem. Athi‐Kapiti ecosystem comprises Nairobi National Park and the Athi‐Kapiti plains (community livestock grazing grounds). Land use information was obtained from existing literature. Pin frame technique and harvest method were used for plant biomass sampling, while road and foot counts were conducted for migratory large herbivores and livestock within the ecosystem, from November 2003 to May 2004. Emphasis was given to the wildebeest (Connechaetes taurinus), zebra (Equus burchelli) and cattle. Results show that green plant biomass available in the park was significantly different from that on Athi‐Kapiti plains [Wilcoxon (two‐tailed), P < 0.05]. Further analysis showed significant seasonal differences in the park [T test (two‐tailed), P < 0.05]. In the community grazing area, significant monthly and seasonal variations in plant biomass were evident (one way ANOVA, P < 0.05). In summary, more wildebeest were observed on Athi‐Kapiti plains than in the park. The zebra showed monthly variations within the whole ecosystem, resulting in a distinct movement pattern. Plant biomass varied depending on the rainfall, which in turn influenced the movement of migratory herbivores within the ecosystem.
Tree density and biomass assessment in agricultural systems around Lake Victoria, Uganda
Authors: Isabirye M. , Verbist B. , Magunda M. K. , Poesen J. , Deckers J.
Published: April 2008

Soil erosion caused by low vegetation cover associated with agricultural land use in the catchment is blamed for the eutrophication of Lake Victoria. Above‐ground biomass as an indicator of vegetation cover and biodiversity was assessed using the Normalized Difference Vegetation Index, estimation of tree density and biomass with the aim of assessing the extent to which vegetation covers the soil surface. Tree density is significantly different between agricultural and semi‐natural systems with an average of 96 and 90 trees ha−1 observed in Rakai and Mayuge respectively. Agricultural fields in Mayuge (9.4 ton ha−1) are associated with significantly higher tree biomass compared with those in Rakai (7.6 ton ha−1). Semi‐natural systems in Rakai have an average tree biomass of 10.1 ton ha−1. Agricultural land use systems in the Lake Victoria catchment of Mayuge resemble semi‐natural systems in terms of tree biomass as seen from satellite image analysis, supported by extensive field observations. The high and medium biomass cover does imply a relatively continuous vegetative ground cover that would minimize soil loss due to water erosion.