bluuebunny/crossref_metadata_2025 huggingface dataset:
Embedding theorems and boundary-value problems for cusp domains
Authors: Gol’dshtein V. , Vasiltchik M.
Published: December 2009

We study the Robin boundary-value problem for bounded domains with isolated singularities. Because trace spaces of space

W

2

1

(
D
)

W_{2}^{1}(D)

on boundaries of such domains are weighted Sobolev spaces

L

2
,
ξ

(
∂
D
)

L^{2,\xi }(\partial D)

, existence and uniqueness of corresponding Robin boundary-value problems depends on properties of embedding operators

I

1

:

W

2

1

(
D
)
→

L

2

(
D
)

I_{1}:W_{2}^{1}(D)\rightarrow L^{2}(D)

and

I

2

:

W

2

1

(
D
)
→

L

2
,
ξ

(
∂
D
)

I_{2}:W_{2}^{1}(D)\rightarrow L^{2,\xi }(\partial D)

i.e. on types of singularities. We obtain an exact description of weights

ξ
\xi

for bounded domains with ‘outside peaks’ on its boundaries. This result allows us to formulate correctly the corresponding Robin boundary-value problems for elliptic operators. Using compactness of embedding operators

I

1

,

I

2

I_{1},I_{2}

, we prove also that these Robin boundary-value problems with the spectral parameter are of Fredholm type.
Sets with integral distances in finite fields
Authors: Iosevich Alex , Shparlinski Igor , Xiong Maosheng
Published: December 2009

Given a positive integer

n
n

, a finite field

F

q

\mathbb F_q

of

q
q

elements (

q
q

odd), and a non-degenerate quadratic form

Q
Q

on

F

q
n

\mathbb {F}_q^n

, in this paper we study the largest possible cardinality of subsets

E

⊆

F

q
n

\mathcal {E} \subseteq \mathbb {F}_q^n

with pairwise integral

Q
Q

-distances; that is, for any two vectors
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="bold left-brace x right-brace equals left-parenthesis x 1 comma ellipsis comma x Subscript n Baseline right-parenthesis comma bold left-brace y right-brace equals left-parenthesis y 1 comma ellipsis comma y Subscript n Baseline right-parenthesis element-of script upper E">

{x}

=
(

x
1

,
…
,

x
n

)
,

{y}

=
(

y
1

,
…
,

y
n

)
∈

E

\textbf {{x}}=(x_1, \ldots ,x_n), \textbf {{y}}=(y_1,\ldots ,y_n) \in \mathcal {E}

, one has
\[

Q
(

{x}

−

{y}

)
=

u
2

Q(\textbf {{x}}-\textbf {{y}})=u^2

\]
for some

u
∈

F

q

u \in \mathbb F_q

.
McKay correspondence for canonical orders
Authors: Chan Daniel
Published: December 2009

Canonical orders, introduced in the minimal model program for orders, are simultaneous generalisations of Kleinian singularities

k
[
[
s
,
t
]

]
G

k[[s,t]]^G

,

G
>
S

L
2

G > SL_2

and their associated skew group rings

k
[
[
s
,
t
]
]
∗
G

k[[s,t]]*G

. In this paper, we construct minimal resolutions of canonical orders via non-commutative cyclic covers and skew group rings. This allows us to exhibit a derived equivalence between minimal resolutions of canonical orders and the skew group ring form of the canonical order in all but one case. The Fourier-Mukai transform used to construct this equivalence allows us to make explicit the numerical version of the McKay correspondence for canonical orders noted in Chan, Hacking, and Ingalls, which relates the exceptional curves of the minimal resolution to the indecomposable reflexive modules of the canonical order.
Robust ergodic properties in partially hyperbolic dynamics
Authors: Andersson Martin
Published: December 2009

We study ergodic properties of partially hyperbolic systems whose central direction is mostly contracting. Earlier work of Bonatti and Viana (2000) about existence and finitude of physical measures is extended to the case of local diffeomorphisms. Moreover, we prove that such systems constitute a

C
2

C^2

-open set in which statistical stability is a dense property. In contrast, all mostly contracting systems are shown to be stable under small random perturbations.
Small-time compactness and convergence behavior of deterministically and self-normalised Lévy processes
Authors: Maller Ross , Mason David
Published: December 2009

Consider a Lévy process

X
t

X_t

with quadratic variation process

V
t

=

σ
2

t
+

∑

0
>
s
≤
t

(
Δ

X
s

)
2

V_t=\sigma ^2 t+ \sum _{0>s\le t} (\Delta X_s)^2

,

t
>
0

t>0

, where

Δ

X
t

=

X
t

−

X

t
−

\Delta X_t=X_t-X_{t-}

denotes the jump process of

X
X

. We give stability and compactness results, as

t

↓

0

t\,\downarrow \,0

, for the convergence both of the deterministically normed (and possibly centered) processes

X
t

X_t

and

V
t

V_t

, as well as theorems concerning the “self-normalised” process

X

t

/

V
t

X_{t}/\sqrt {V_t}

. Thus, we consider the stochastic compactness and convergence in distribution of the 2-vector
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="left-parenthesis left-parenthesis upper X Subscript t Baseline minus a left-parenthesis t right-parenthesis right-parenthesis slash b left-parenthesis t right-parenthesis comma upper V Subscript t Baseline slash b left-parenthesis t right-parenthesis right-parenthesis">

(
(

X
t

−
a
(
t
)
)

/

b
(
t
)
,

V
t

/

b
(
t
)
)

\left ((X_t-a(t))/b(t), V_t/b(t)\right )

, for deterministic functions

a
(
t
)

a(t)

and

b
(
t
)
>
0

b(t)>0

, as

t

↓

0

t\,\downarrow \,0

, possibly through a subsequence; and the stochastic compactness and convergence in distribution of

X

t

/

V
t

X_{t}/\sqrt {V_t}

, possibly to a nonzero constant (for stability), as

t

↓

0

t\,\downarrow \,0

, again possibly through a subsequence.

As a main application it is shown that

X

t

/

V
t

⟶

D

N
(
0
,
1
)

X_{t}/\sqrt {V_t}\stackrel {\mathrm {D}}{\longrightarrow } N(0,1)

, a standard normal random variable, as

t

↓

0

t\,\downarrow \,0

, if and only if

X
t

/

b
(
t
)

⟶

D

N
(
0
,
1
)

X_t/b(t)\stackrel {\mathrm {D}}{\longrightarrow } N(0,1)

, as

t
↓
0

t\downarrow 0

, for some nonstochastic function

b
(
t
)
>
0

b(t)>0

; thus,

X
t

X_t

is in the domain of attraction of the normal distribution, as

t

↓

0

t\,\downarrow \,0

, with or without centering constants being necessary (these being equivalent).

We cite simple analytic equivalences for the above properties, in terms of the Lévy measure of

X
X

. Functional versions of the convergences are also given.
Squares of Menger-bounded groups
Authors: Machura Michał , Shelah Saharon , Tsaban Boaz
Published: December 2009

Using a portion of the Continuum Hypothesis, we prove that there is a Menger-bounded (also called

o
o

-bounded) subgroup of the Baer-Specker group

Z

N

\mathbb {Z}^{\mathbb {N}}

, whose square is not Menger-bounded. This settles a major open problem concerning boundedness notions for groups and implies that Menger-bounded groups need not be Scheepers-bounded. This also answers some questions of Banakh, Nickolas, and Sanchis.
The histone variant macroH2A1 marks repressed autosomal chromatin, but protects a subset of its target genes from silencing
Authors: Gamble Matthew J. , Frizzell Kristine M. , Yang Christine , Krishnakumar Raga , Kraus W. Lee
Published: December 2009

MacroH2A1 is a histone variant that is enriched on the inactive X chromosome (Xi) in mammals and is postulated to play an important, but unknown, role in the repression of gene expression. Here we show that, although macroH2A1 marks repressed autosomal chromatin, it positively regulates transcription when located in the transcribed regions of a subset of its target genes. We used chromatin immunoprecipitation (ChIP) coupled with tiling microarrays (ChIP–chip) to determine the genomic localization of macroH2A1 in IMR90 human primary lung fibroblasts and MCF-7 breast cancer cells. The patterns of macroH2A1 deposition are largely similar across the autosomes of both cell lines. Our studies revealed a genomic localization pattern unique among histone variants; namely, the occupation by macroH2A1 of large chromatin domains (>500 kb in some cases) that contain repressive chromatin marks (e.g., histone H3 Lys 27 trimethylation). The boundaries of macroH2A1-containing domains tend to occur in promoter-proximal regions. Not all promoters, however, serve as macroH2A1 boundaries; many macroH2A1-containing chromatin domains invade the transcribed regions of genes whose products play key roles in development and cell–cell signaling. Surprisingly, the expression of a subset of these genes is positively regulated by macroH2A1. MacroH2A1 also plays a role in augmenting signal-regulated transcription, specifically for genes responsive to serum starvation. Collectively, our results document an unexpected role for macroH2A1 in the escape from heterochromatin-associated silencing and the enhancement of autosomal gene transcription.
Antagonistic HLH/bHLH Transcription Factors Mediate Brassinosteroid Regulation of Cell Elongation and Plant Development in Rice andArabidopsis
Authors: Zhang Li-Ying , Bai Ming-Yi , Wu Jinxia , Zhu Jia-Ying , Wang Hao , Zhang Zhiguo , Wang Wenfei , Sun Yu , Zhao Jun , Sun Xuehui , Yang Hongjuan , Xu Yunyuan , Kim Soo-Hwan , Fujioka Shozo , Lin Wen-Hui , Chong Kang , Lu Tiegang , Wang Zhi-Yong
Published: December 2009

In rice (Oryza sativa), brassinosteroids (BRs) induce cell elongation at the adaxial side of the lamina joint to promote leaf bending. We identified a rice mutant (ili1-D) showing an increased lamina inclination phenotype similar to that caused by BR treatment. The ili1-D mutant overexpresses an HLH protein homologous to Arabidopsis thaliana Paclobutrazol Resistance1 (PRE1) and the human Inhibitor of DNA binding proteins. Overexpression and RNA interference suppression of ILI1 increase and reduce, respectively, rice laminar inclination, confirming a positive role of ILI1 in leaf bending. ILI1 and PRE1 interact with basic helix-loop-helix (bHLH) protein IBH1 (ILI1 binding bHLH), whose overexpression causes erect leaf in rice and dwarfism in Arabidopsis. Overexpression of ILI1 or PRE1 increases cell elongation and suppresses dwarf phenotypes caused by overexpression of IBH1 in Arabidopsis. Thus, ILI1 and PRE1 may inactivate inhibitory bHLH transcription factors through heterodimerization. BR increases the RNA levels of ILI1 and PRE1 but represses IBH1 through the transcription factor BZR1. The spatial and temporal expression patterns support roles of ILI1 in laminar joint bending and PRE1/At IBH1 in the transition from growth of young organs to growth arrest. These results demonstrate a conserved mechanism of BR regulation of plant development through a pair of antagonizing HLH/bHLH transcription factors that act downstream of BZR1 in Arabidopsis and rice.
How not to be seen: does eutrophication influence three‐spined stickleback Gasterosteus aculeatus sneaking behaviour?
Authors: Vlieger L. , Candolin U.
Published: December 2009

Experiments done in aquaria under control and either turbid or densely vegetated conditions indicated that three‐spined stickleback Gasterosteus aculeatus sneaking behaviour is affected by decreased underwater visibility. Success of sneaking behaviour decreased significantly under increased turbidity but not increased vegetation density. The total number of sneaking attempts, including unsuccessful ones, was not affected by either form of decreasing visibility.
Body armour and lateral‐plate reduction in freshwater three‐spined sticklebackGasterosteus aculeatus: adaptations to a different buoyancy regime?
Authors: Myhre F. , Klepaker T.
Published: December 2009

Several factors related to buoyancy were compared between one marine and two freshwater populations of three‐spined sticklebackGasterosteus aculeatus. Fish from all three populations had buoyancy near to neutral to the ambient water. This showed that neither marine nor freshwaterG. aculeatusused swimming and hydrodynamic lift to prevent sinking. Comparing the swimbladder volumes showed that freshwater completely platedG. aculeatushad a significantly larger swimbladder volume than both completely plated marine and low‐plated freshwaterG. aculeatus. Furthermore, body tissue density was lower in low‐platedG. aculeatusthan in the completely plated marine and freshwater fish. The results show thatG. aculeatuseither reduce tissue density or increase swimbladder volume to adapt to lower water density. Mass measurements of lateral plates and pelvis showed that loss of body armour in low‐platedG. aculeatuscould explain the tissue density difference between low‐plated and completely platedG. aculeatus. This suggests that the common occurrence of plate and armour reduction in freshwaterG. aculeatuspopulations can be an adaptation to a lower water density.
The Darwinian sticklebackGasterosteus aculeatus: a history of evolutionary studies*
Authors: Wootton R. J.
Published: December 2009

The history of studies on the taxonomy and evolutionary biology of the three‐spined sticklebackGasterosteus aculeatusfrom the 18th century to the present is reviewed. After the publication of Darwin'sOrigin of the Species, four important dates, 1925, 1947, 1967 and 2001, are identified as marking major gains in the understanding of the evolution of the diversity in morphological, life‐history, physiological and behavioural traits that characterizesG. aculeatus. The period 1925–1970 led to the identification of the main themes of research: status and adaptive significance of lateral‐plate morphs; inter and intrapopulation trait variation in freshwater residentG. aculeatusand the adaptive significance of the variation. Between 1970 and 2001, these themes were investigated using variation observed particularly along the Pacific coast of the U.S.A. and Canada, notably in the Cook Inlet region of Alaska and the Haida Gwaii Archipelago. Studies on adaptive radiation and reproductive isolation in lacustrine, ecomorph pairs (limnetics and benthics) discovered in the Strait of Georgia region have been particularly productive. From 2001, the application of genomic studies to these problems began to open up the study of the relationships between genotype, phenotype and selective advantage to causal analysis.
Implications of a fossil stickleback assemblage for Darwinian gradualism
Authors: Bell M. A.
Published: December 2009

Darwin postulated that a complete fossil record would contain numerous gradual transitions between ancestral and descendant species, but 150 years after publication ofThe Origin of Species, few such transitions have materialized. The fossil sticklebackGasterosteus doryssusand the deposit in which it occurs provide excellent conditions to detect such transitions. Abundant, well‐preserved fossils occur in a stratigraphic setting with fine temporal resolution. The paleoecology ofG. doryssusresembles the ecology of modern lakes that harbour the phenotypically similar three‐spined sticklebackGasterosteus aculeatus.Gasterosteus aculeatusare primitively highly armoured, butG. doryssuscomprised two contemporaneous biological species with relatively weak armour, including a near‐shore, benthic feeder (benthic) and an offshore planktivore (limnetic). The benthic species expanded its range into the limnetic zone of the lake, where it apparently switched to planktivory and evolved reduced armour withinc.5000 years in response to directional selection. Although gradual evolution of mean phenotypes occurred, a single major gene caused much of evolutionary change of the pelvic skeleton. Thus, Darwin's expectation that transitions between species in the fossil record would be gradual was met at a fine time scale, but for pelvic structure, a well‐studied trait, his expectation that gradual change would depend entirely on numerous, small, heritable differences among individuals was incorrect.
The hypersensitive response induced by the V2 protein of a monopartite begomovirus is countered by the C2 protein
Authors: MUBIN MUHAMMAD , AMIN IMRAN , AMRAO LUQMAN , BRIDDON ROB W. , MANSOOR SHAHID
Published: December 2009

A functional analysis of the V2 protein of two monopartite begomoviruses, Papaya leaf curl virus (PaLCuV) and Cotton leaf curl Kokhran virus (CLCuKoV), has been performed. Expression of the V2 gene from a Potato virus X (PVX) vector resulted in severe leaf curling followed by a hypersensitive response (HR) in Nicotiana benthamiana and N. tabacum, demonstrating that the V2 protein is a pathogenicity determinant and a target of host defence responses. Agroinfiltration of a PVX vector expressing the V2 protein resulted in cell death in the infiltrated area. Subsequently, a systemic HR developed that was associated with the long‐distance spread of the virus and led to the death of the plant. V2 amino acid sequences encompassing a conserved putative protein kinase C (PKC) phosphorylation motif were shown to be essential for the elicitation of cell death. In co‐inoculation experiments, the transient expression of the C2 protein of PaLCuV or Cotton leaf curl Multan virus under the control of the Cauliflower mosaic virus 35S promoter inhibited the HR induced by V2 in the agroinfiltrated area. These findings demonstrate that the V2 protein of monopartite begomoviruses is a pathogenicity determinant and induces an HR that can be suppressed by the C2 protein. The induction and suppression of HR have been demonstrated previously in bipartite begomoviruses and our results extend this to monopartite begomoviruses.
Potyviral resistance derived from cultivars of Phaseolus vulgaris carrying bc‐3 is associated with the homozygotic presence of a mutated eIF4E allele
Authors: NADERPOUR MASOUD , LUND OLE SØGAARD , LARSEN RICHARD , JOHANSEN ELISABETH
Published: December 2009

Eukaryotic translation initiation factors (eIFs) play a central role in potyviral infection. Accordingly, mutations in the gene encoding eIF4E have been identified as a source of recessive resistance in several plant species. In common bean, Phaseolus vulgaris, four recessive genes, bc‐1, bc‐2, bc‐3 and bc‐u, have been proposed to control resistance to the potyviruses Bean common mosaic virus (BCMV) and Bean common mosaic necrosis virus. In order to identify molecular entities for these genes, we cloned and sequenced P. vulgaris homologues of genes encoding the eIF proteins eIF4E, eIF(iso)4E and nCBP. Bean genotypes reported to carry bc‐3 resistance were found specifically to carry non‐silent mutations at codons 53, 65, 76 and 111 in eIF4E. This set of mutations closely resembled a pattern of eIF4E mutations determining potyvirus resistance in other plant species. The segregation of BCMV resistance and eIF4E genotype was subsequently analysed in an F2 population derived from the P. vulgaris all‐susceptible genotype and a genotype carrying bc‐3. F2 plants homozygous for the eIF4E mutant allele were found to display at least the same level of resistance to BCMV as the parental resistant genotype. At 6 weeks after inoculation, all F2 plants found to be BCMV negative by enzyme‐linked immunosorbent assay were found to be homozygous for the mutant eIF4E allele. In F3 plants homozygous for the mutated allele, virus resistance was subsequently found to be stably maintained. In conclusion, allelic eIF4E appears to be associated with a major component of potyvirus resistance present in bc‐3 genotypes of bean.
Ecological determinants of herd size in the Thornicroft’s giraffe of Zambia
Authors: Bercovitch Fred B. , Berry Philip S.M.
Published: December 2009

Ecological factors have a pervasive impact on animal population sizes and the structure of their social systems. In a number of ungulate species, predator pressure exerts a major influence on group size. Given that giraffe (Giraffa camelopardalis) live in an extremely flexible social system, and that breeding is nonseasonal, they are an ideal species for examining how ecological variables contribute to fluctuations in herd size. We present an analysis of 34 years of data on a population of Thornicroft’s giraffe (G. c. thornicroftiLydekker 1911) that reveal how herd size changes with season and habitat. Sex differences in herd size were apparent, with bulls often travelling as singletons, whereas cows were generally observed with conspecifics. Herds were larger during the wet than dry season, but herd size changed in a parallel fashion across habitats. Giraffe herds were smaller in woodland and thicket areas than in open habitats, regardless of season. We suggest that the regular fluctuations in herd size among giraffe indicate a fission/fusion social system embedded within a larger social community. We conclude that changes in herd size among giraffe reflect a dynamic process regulated by individuals adjusting the number of associates based upon an interaction of foraging, reproductive, social and antipredator strategies.
Trophic level delineation and resource partitioning in a South African afromontane forest bird community using carbon and nitrogen stable isotopes
Authors: Symes Craig T. , Woodborne Stephan M.
Published: December 2009

Southern African forests are naturally fragmented yet hold a disproportionately high number of bird species. Carbon and nitrogen stable isotopes were measured in feathers from birds captured at Woodbush (n = 27 species), a large afromontane forest in the eastern escarpment of Limpopo province, South Africa. The δ13C signatures of a range of forest plants were measured to categorise the food base. Most plants sampled, including two of five grass species, had δ13C signatures typical of a C3 photosynthetic pathway (−29.5 ± 1.9‰). Three grass species had a C4 signature (−12.0 ± 0.6‰). Most bird species had δ13C values representing a predominantly C3‐based diet (−24.8‰ to −20.7‰). δ15N values were as expected, with higher levels of enrichment associated with a greater proportion of dietary animal matter. The cohesive isotopic niche defining most species (n = 22), where the ranges for δ13C and δ15N were 2.4‰ and 3.4‰, respectively, highlight the difficulties in understanding diets of birds in a predominantly C3‐based ecosystem using carbon and nitrogen stable isotopes. However, variation in isotopic values between and within species provides insight into possible niche width and the use of resources by different birds within a forest environment.
Characterization of the porcinetransferringene (TF ) and its association with disease severity following an experimentalActinobacillus pleuropneumoniaeinfection
Authors: Daniłowicz E. , Martinez‐Arias R. , Dolf G. , Singh M. , Probst I. , Tümmler B. , Höltig D. , Waldmann K.‐H. , Gerlach G.‐F. , Stanke F. , Leeb T. ,   the FUGATO‐consortium IRAS
Published: December 2009

Transferrin (TF)‐mediated provision of iron is essential for a productive infection by many bacterial pathogens, and iron‐depletion of TF is a first line defence against bacterial infections. Therefore, thetransferrin(TF) gene can be considered a candidate gene for disease resistance. We obtained the complete DNA sequence of the porcineTFgene, which spans 40 kb and contains 17 exons. We identified polymorphisms on a panel of 10 different pig breeds. Comparative intra‐ and interbreed sequence analysis revealed 62 polymorphisms in theTFgene including one microsatellite. Ten polymorphisms were located in the coding sequence of theTFgene. Four SNPs (c.902A>T, c.980G>A, c.1417A>G, c.1810A>C) were predicted to cause amino acid exchanges (p.Lys301Ile, p.Arg327Lys, p.Lys473Glu, p.Asn604His). We performed association analyses using six selectedTFmarkers and 116 pigs experimentally infected withActinobacillus pleuropneumoniaeserotype 7. The analysis showed breed‐specificTFallele frequencies. In German Landrace, we found evidence for a possible association of the severity ofA. pleuropneumoniaeinfection withTFgenotypes.
Myrmecochorous plants use chemical mimicry to cheat seed‐dispersing ants
Authors: Pfeiffer Martin , Huttenlocher Heiko , Ayasse Manfred
Published: December 2009

1. Deceptive species are a characteristic trait of insect–plant mutualisms. Deception of pollinators is essential for reproduction in diverse plant species; however, mimicry in seed dispersal is almost unknown. Myrmecochory, the dispersal of diaspores by ants, is a mutualism in which the elaiosome, a lipid‐rich seed appendage, works as an ant reward. This coevolved interaction may be exploited by cheating, non‐rewarding diaspores that mimic elaiosomes.

2. Our study assesses the impact of the morphology and fatty acid composition of diaspores on ant dispersal in rewarding and cheating myrmecochores and non‐myrmecochorous species. Four elaiosome types (defined by Sernander 1906) were included in our research: the ‘Viola odorata type’, with a clearly defined elaiosome, the similar but diplochorous ‘Euphorbia type’ with an additional ballistic dispersal of diaspores, and the ‘Puschkinia’ and ‘Hepatica’ types, which we classify as ‘cheaters’ as they mimic ant rewards by chemical cues.

3. We tested the influence of morphology, chemical composition of diaspores and presence of rewards on removal rates of diaspores, dummies impregnated with seed extracts and pure fatty acids and scent‐standardized diaspores in a population of Formica polyctena ants with 10 European spring ephemerals, mostly Ranunculaceae. The main free fatty acids of diaspores were identified by gas chromatography and mass spectrometric analysis.

4. Removal rates of diaspores and dummies treated with seed extracts were significantly influenced by their fatty acid composition. Discriminant function analysis confirmed oleic acid as the main trigger substance eliciting seed‐removal behaviour by ants in most species. Oleic acid content and removal rates differed among elaiosome types and were highest in rewarding myrmecochores, lower in cheaters and smallest in non‐myrmecochorous seeds. Removal rates of scent‐standardized diaspores did not differ among mutualists and cheaters suggesting a selective pressure for morphological adaptation and were lowest in non‐myrmecochorous species, thus corroborating an influence of diaspore morphology on ant‐removal patterns.

5. For the first time, we demonstrate chemical mimicry in myrmecochory as a means of seed dispersal. Evolutionary stability of the ant–seed mutualism is maintained by the ability of ants to discriminate between certain types of rewards and to respond with differential diaspore distribution rates.
Molecular investigations into a globally important carbon pool: permafrost‐protected carbon in Alaskan soils
Authors: WALDROP M. P. , WICKLAND K. P. , WHITE III R. , BERHE A. A. , HARDEN J. W. , ROMANOVSKY V. E.
Published: December 2009

The fate of carbon (C) contained within permafrost in boreal forest environments is an important consideration for the current and future carbon cycle as soils warm in northern latitudes. Currently, little is known about the microbiology or chemistry of permafrost soils that may affect its decomposition once soils thaw. We tested the hypothesis that low microbial abundances and activities in permafrost soils limit decomposition rates compared with active layer soils. We examined active layer and permafrost soils near Fairbanks, AK, the Yukon River, and the Arctic Circle. Soils were incubated in the lab under aerobic and anaerobic conditions. Gas fluxes at −5 and 5 °C were measured to calculate temperature response quotients (Q10). The Q10 was lower in permafrost soils (average 2.7) compared with active layer soils (average 7.5). Soil nutrients, leachable dissolved organic C (DOC) quality and quantity, and nuclear magnetic resonance spectroscopy of the soils revealed that the organic matter within permafrost soils is as labile, or even more so, than surface soils. Microbial abundances (fungi, bacteria, and subgroups: methanogens and Basidiomycetes) and exoenzyme activities involved in decomposition were lower in permafrost soils compared with active layer soils, which, together with the chemical data, supports the reduced Q10 values. CH4 fluxes were correlated with methanogen abundance and the highest CH4 production came from active layer soils. These results suggest that permafrost soils have high inherent decomposability, but low microbial abundances and activities reduce the temperature sensitivity of C fluxes. Despite these inherent limitations, however, respiration per unit soil C was higher in permafrost soils compared with active layer soils, suggesting that decomposition and heterotrophic respiration may contribute to a positive feedback to warming of this eco region.
Slow response of soil organic matter to the reduction in atmospheric nitrogen deposition in a Norway spruce forest
Authors: DÖRR NICOLE , KAISER KLAUS , MIKUTTA ROBERT , GUGGENBERGER GEORG
Published: December 2009

Global nitrogen (N) deposition rates in terrestrial environments have quadrupled since preindustrial times, causing structural and functional changes of ecosystems. Different emission reduction policies were therefore devised. The aim of our study was to investigate if, and over what timescale, processes of soil organic matter (OM) transformation respond to a decline in atmospheric N deposition. A N‐saturated spruce forest (current N deposition: 34 kg ha−1 yr−1; critical N load: 14 kg ha−1 yr−1), where N deposition has been reduced to 11.5 kg ha−1 yr−1 since 1991, was studied. Besides organic C and organic and inorganic N, noncellulosic carbohydrates, amino sugars and amino acids were determined. A decline in organic N in litter indicated initial effects at plant level. However, there were no changes in biomarkers upon the reduction in N deposition. In addition, inorganic N was not affected by reduced N deposition. The results showed that OM cycling and transformation processes have not responded so far. It was concluded that no direct N deposition effects have occurred due to the large amount of stored organic N, which seems to compensate for the reduction in deposited N. Obviously, the time span of atmospheric N reduction (about 14.5 years) is too short compared with the mean turnover time of litter to cause indirect effects on the composition of organic C and N compounds. It is assumed that ecological processes, such as microbial decomposition or recycling of organic N and C, react slowly, but may start within the next decade with the incorporation of the new litter.
Prophylactic therapy with Fibrogammin® P is associated with a decreased incidence of bleeding episodes: a retrospective study
Authors: LUSHER J. , PIPE S. W. , ALEXANDER S. , NUGENT D.
Published: December 2009

Summary.  Congenital factor XIII (FXIII) deficiency is an extremely rare, yet potentially life‐threatening, bleeding disorder, with a 30% rate of spontaneous intracranial haemorrhage. Routine prophylactic management is recommended for all individuals with clinically relevant (FXIII) deficiency and for all symptomatic individuals with congenital factor deficiency. Fibrogammin® P is a purified, pasteurized concentrate of FXIII that appears to carry negligible risk of viral transmission, unlike other unprocessed products containing FXIII. An ongoing Phase II/III study of Fibrogammin® P in patients with congenital FXIII deficiency is being conducted to evaluate the prophylactic efficacy and long‐term safety of this product. Using retrospective chart review data from subjects enrolled in the Phase II/III study, the current analysis was designed to compare spontaneous bleed‐event rates prior to and after the initiation of Fibrogammin® P prophylaxis. Seven subjects were evaluable for comparison, having received no other prophylactic FXIII‐containing product during the 24 months prior to study entry. The mean annual number of spontaneous bleeds was 2.5 events per year prior to Fibrogammin® P prophylaxis and 0.2 events per year during Fibrogammin® P prophylaxis (P = 0.01). Patients reported no severe bleeds during Fibrogammin® P therapy. This small sample supports a consistent and clinically meaningful reduction in spontaneous bleeding with prophylactic use of Fibrogammin® P.
Differential effect of specific gr/gr deletion subtypes on spermatogenesis in the Chinese Han population
Authors: Yang Y. , Ma M. , Li L. , Su D. , Chen P. , Ma Y. , Liu Y. , Tao D. , Lin L. , Zhang S.
Published: December 2009

As a common variation in the azoospermia factor c (AZFc) region of Y chromosome, the gr/gr deletion is regarded as a significant risk factor for spermatogenic impairment, whereas the association of the deletion’s phenotypic expression with Y‐chromosomal background is still a subject of debate. To further investigate the contribution of the deletion to spermatogenic impairment in different Y‐chromosomal haplogroups, the partial AZFc deletion was detected with AZFc‐specific sequence tagged sites, gene dosage and gene copy analyses of deleted in azoospermia (DAZ), chromodomain Y1 (CDY1) and basic protein Y2 (BPY2) in 1426 azoo/oligozoospermic and 672 normozoospermic men from a Chinese population. The haplogrouping was performed in 231 deletion carriers with 12 polymorphic loci of Y chromosome. As a result, five gr/gr rearrangement types in eight Y haplogroups were observed, in which the simple gr/gr deletion was the most common type, and its frequency was significantly higher in men with azoo/oligozoospermia relative to normozoospermia. Also the distribution of gr/gr‐rearranged Y haplogroups was significantly different between the two groups, in which gr/gr‐deleted haplogroups C and DE were more common in men with azoo/oligozoospermia. In the 6 gr/gr copy deletion haplotypes, the frequencies of DAZ1/DAZ2+CDY1a or CDY1b deletion were significantly higher in men with azoo/oligozoospermia, while all DAZ3/DAZ4+CDY1b+BPY2.2 or 2.3 deletions were found only in haplogroup Q1 without any distribution difference between the azoo/oligozoospermic and normozoospermic groups. This study provided further evidence for the existence of multiple subtypes of gr/gr deletion and indicates that gr/gr‐DAZ1/DAZ2 deletion is a significant risk factor. However, the association of the phenotypic variation of gr/gr deletion with Y‐chromosomal haplogroups is not definite yet, because of the limited amounts of the deletions observed in each of the haplogroups and the lack of the quantitative trait analyses such as sperm density analysis. The fact that a common gr/gr copy deletion haplotype was found exclusively in the Y hgr Q1, without pathogenic consequences, implies the importance of haplogrouping and of copy deletion typing prior to genetic counselling of deletion carriers of Chinese descent.
Effectiveness of a presentation on infant oral health care for parents
Authors: ROTHE VINCENT , KEBRIAEI AMY , PITNER SHERYL , BALLUFF MARY , SALAMA FOUAD
Published: December 2009

Purpose.  The aim of this study was to evaluate an infant oral health education programme, using a pre–post test design, for parents attending a paediatric clinic.

Methods.  The subjects were parents attending the well baby appointments at 3, 6, and 9 months of age. The study participants were men and women, all with an infant between 3 and 12 months of age. A 16 question assessment in the form of a questionnaire was completed immediately before and after the introduction of a 30 min educational intervention in the form of a PowerPoint presentation and a video of infant oral hygiene for parents. The parents completed the questionnaire twice (pre–post test design) in the same visit. Recruited parents attended only one presentation. The presentation educated parents about infant oral health and provided anticipatory guidance.

Results.  Forty‐seven parents or caretakers participated in the study. On the pre‐test 28% had a score of 70% or less, and on the post‐test 87% got a score of 88% or better. On the pre‐test, 72% had a score of 70% or higher, and on the post‐test 87% got a score of 88% or higher. Most parents (80%) reported that the presentation was helpful and indicated that the information would change the way they care for their baby’s teeth at home.

Conclusion.  This study demonstrated the effectiveness of a 30 min PowerPoint and Video presentation in improving the oral health knowledge of parents caring for an infant.
Periodontal disease in mothers indicates risk in their children
Authors: PÄHKLA ENE‐RENATE , JÕGI EERIK , NURK ALLAN , PISAREV HETI , KOPPEL TAIVE , NAABER PAUL , SAAG MARE , LÕIVUKENE KRISTA
Published: December 2009

Introduction.  It is well established that severe periodontitis clusters in families, but there are no data about the relationship between mothers with chronic periodontitis and their children’s periodontal status.

Objective.  To evaluate a risk for periodontal diseases in children of periodontally diseased and healthy mothers.

Methods.  Four study groups were included: (I) 20 female patients with untreated generalized severe chronic periodontitis, (II) their children (34), (III) 13 periodontally healthy mothers and (IV) their children (13). Material was collected from years 2004–2006. The clinical examination included registration of visible plaque index, modified gingival index and, bleeding sites on probing. Periodontal microbiological samples were obtained from all study subjects and the isolates were identified according to morphology and biochemical profiles; similar interfamilial pathogens were compared by PCR‐technique.

Results.  The children of diseased mothers more frequently had periodontal diseases, especially gingivitis. In addition, clinical parameters of gingival inflammation were more expressed and oral hygiene was worse in this group of children. VPI and VPI% of the diseased and healthy mothers differed significantly. The most common oral pathogens were P. intermedia/nigrescens and A. actinomycetemcomitans. The children of healthy mothers harboured pathogens less frequently than the children of diseased mothers. The sharing of P. intermedia/nigrescens was more frequent (5 families) than A. actinomycetemcomitans (2 families).

Conclusion.  Maternal indicators, such as periodontitis, hygiene habits, and periodontal microflora are risk factors for childhood periodontal diseases, and might be predictive of future childhood and adolescent periodontitis.
Both genes in the Marinomonas mediterranea lodAB operon are required for the expression of the antimicrobial protein lysine oxidase
Authors: Gómez Daniel , Lucas‐Elío Patricia , Solano Francisco , Sanchez‐Amat Antonio
Published: December 2009

The melanogenic marine bacterium Marinomonas mediterranea synthesizes a novel antimicrobial protein (LodA) with lysine‐epsilon oxidase activity (EC 1.4.3.20). Homologues to LodA have been detected in several Gram‐negative bacteria, where they are involved in biofilm development. Adjacent to lodA is located a second gene, lodB, of unknown function. This genomic organization is maintained in all the microorganisms containing homologues to these genes. In this work we show that lodA and lodB constitute an operon. Western blot analysis and enzymatic determinations revealed that LodA is secreted to the external medium when the culture reaches the stationary phase. LodB, on the other hand, has only been detected inside cells, but it is not secreted. The expression of the lysine‐epsilon oxidase (LOD) activity in M. mediterranea requires functional copies of both genes since mutants lacking either lodA or lodB do not show any LOD activity. The active form of LodA containing the quinonic cofactor is intracellularly generated in a process that takes place only in the presence of LodB, suggesting that the latter is involved in this process. Moreover, in the absence of one of the proteins, the stability of the partner protein is compromised leading to a marked decrease in its cellular levels.
The role of configuration and coupling in autoregulatory gene circuits
Authors: Wu Kang , Rao Christopher V.
Published: December 2009

Autoregulatory gene circuits can be physically encoded within the genome in a number of different configurations. By physical encoding, we mean the orientation and relative proximity of the genes within the circuit. In this work, we quantified the behaviour of an inducible, negatively autoregulated gene circuit arranged in different transcriptional configurations using the tetRA circuit from Tn10 as our basis. Mathematical modelling predicted that circuits arranged in configurations where the expression of the transcription factor is decoupled from its target genes afforded more flexibility relative to configurations where expression is coupled. We found that these decoupled configurations reduced the concentration of transcription factor needed to regulate inducible expression from the circuit. As lower concentrations of transcription factor were required, these decoupled configurations could also be activated at much lower concentrations of the inducer. We experimentally validated these predictions in Escherichia coli by comparing the response of synthetic circuits based on the tetRA circuit arranged in different configurations. Collectively, these results provide one example of how the arrangement of a gene circuit within the genome can affect its behaviour.
Borrelia burgdorferi locus BB0795 encodes a BamA orthologue required for growth and efficient localization of outer membrane proteins
Authors: Lenhart Tiffany R. , Akins Darrin R.
Published: December 2009

The outer membrane (OM) of the pathogenic diderm spirochete, Borrelia burgdorferi, contains integral β‐barrel outer membrane proteins (OMPs) in addition to its numerous outer surface lipoproteins. Very few OMPs have been identified in B. burgdorferi, and the protein machinery required for OMP assembly and OM localization is currently unknown. Essential OM BamA proteins have recently been characterized in Gram‐negative bacteria that are central components of an OM β‐barrel assembly machine and are required for proper localization and insertion of bacterial OMPs. In the present study, we characterized a putative B. burgdorferi BamA orthologue encoded by open reading frame bb0795. Structural model predictions and cellular localization data indicate that the B. burgdorferi BB0795 protein contains an N‐terminal periplasmic domain and a C‐terminal, surface‐exposed β‐barrel domain. Additionally, assays with an IPTG‐regulatable bb0795 mutant revealed that BB0795 is required for B. burgdorferi growth. Furthermore, depletion of BB0795 results in decreased amounts of detectable OMPs in the B. burgdorferi OM. Interestingly, a decrease in the levels of surface‐exposed lipoproteins was also observed in the mutant OMs. Collectively, our structural, cellular localization and functional data are consistent with the characteristics of other BamA proteins, indicating that BB0795 is a B. burgdorferi BamA orthologue.
Two CDC42 paralogues modulate Cryptococcus neoformans thermotolerance and morphogenesis under host physiological conditions
Authors: Ballou Elizabeth R. , Nichols Connie B. , Miglia Kathleen J. , Kozubowski Lukasz , Alspaugh J. Andrew
Published: December 2009

The precise regulation of morphogenesis is a key mechanism by which cells respond to a variety of stresses, including those encountered by microbial pathogens in the host. The polarity protein Cdc42 regulates cellular morphogenesis throughout eukaryotes, and we explore the role of Cdc42 proteins in the host survival of the human fungal pathogen Cryptococcus neoformans. Uniquely, C. neoformans has two functional Cdc42 paralogues, Cdc42 and Cdc420. Here we investigate the contribution of each paralogue to resistance to host stress. In contrast to non‐pathogenic model organisms, C. neoformans Cdc42 proteins are not required for viability under non‐stress conditions but are required for resistance to high temperature. The paralogues play differential roles in actin and septin organization and act downstream of C. neoformans Ras1 to regulate its morphogenesis sub‐pathway, but not its effects on mating. Cdc42, and not Cdc420, is upregulated in response to temperature stress and is required for virulence in a murine model of cryptococcosis. The C. neoformans Cdc42 proteins likely perform complementary functions with other Rho‐like GTPases to control cell polarity, septin organization and hyphal transitions that allow survival in the environment and in the host.
Staphylococcus intermediusbinding to immobilized fibrinogen, fibronectin and cytokeratinin vitro
Authors: Schmidt Vanessa , Nuttall Tim , Fazakerley Jennie , McEwan Neil
Published: December 2009

Bacterial adhesion is a key step in colonization of the skin.Staphylococcus intermediusadheres strongly to canine and feline corneocytes, and adhesion is greater to corneocytes from dogs affected with atopic dermatitis, but comparatively little is known about adhesion‐receptor interaction compared toS. aureus. The aim of this study was to compare the binding ofS. intermediusisolates from healthy (n = 21) and atopic dogs (n = 33) to immobilized human fibronectin and epidermal cytokeratin and canine fibrinogenin vitro.Staphylococcus intermediusand the positive controlS. aureusP1 exhibited concentration‐dependent binding to all three protein layers. The negative controlS. aureusNewman strain andS. hominisdid not bind. The majority ofS. intermediusisolates adhered strongly, and there was no significant difference between isolates from atopic and healthy dogs or from lesional or nonlesional skin of atopic dogs (fibronectinP = 0.971 and 0.837; fibrinogenP = 0.811 and 0.564; cytokeratinP = 0.409 and 0.564). These results suggest thatS. intermediusmay possess specific microbial components recognizing adhesive matrix molecules, likeS. aureus, that bind to the substrates used in this study. Adherence and therefore colonization and infection in canine atopic dermatitis, however, are more likely to be related to host factors rather than the possession of specific virulence factors.
Canine hair‐follicle keratinocytes enriched with bulge cells have the highly proliferative characteristic of stem cells
Authors: Kobayashi Tetsuro , Shimizu Atsushi , Nishifuji Koji , Amagai Masayuki , Iwasaki Toshiroh , Ohyama Manabu
Published: December 2009

Homeostasis of the epidermis and skin appendages is maintained by tissue‐specific stem cells. In mice and humans, two populations of epithelial stem cells have been identified: one in the basal layer of the interfollicular epidermis and another in the bulge area of hair follicles. However, our understanding of canine epithelial stem cells is extremely limited. In this study, in vitro colony‐forming assays were performed to locate highly proliferative keratinocytes in canine skin. Their phenotypic resemblance to epithelial stem cells in other species was also assessed. When equal numbers of epidermal or hair‐follicle keratinocytes were cultured, colonies derived from follicular keratinocytes were significantly larger both in total numbers and size, than those derived from epidermal keratinocytes. In addition, immunoreactivity for CD34, a putative bulge stem‐cell marker in the mouse, was predominantly detected in follicular keratinocytes. Thus in dogs, follicular keratinocytes were distinct from epidermal keratinocytes in proliferative capacity and CD34 expression. Using microdissection, highly proliferative keratinocytes were located within the middle portion of hair follicles, including the bulge area. Immunohistochemical study revealed that keratin 15, an established marker of bulge stem cells in mice and humans, was also predominantly expressed in the canine bulge area. Flow cytometry analysis revealed high numbers of keratin‐15‐positive cells in the highly proliferative keratinocyte compartment. Of note, keratin 15high cells possessed the phenotypic characteristics of putative stem cells. This study represents the first in vitro identification and isolation of highly proliferative canine keratinocytes, which represent candidate epithelial stem cells.