bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparative genomics of bacterial zinc regulons: Enhanced ion transport, pathogenesis, and rearrangement of ribosomal proteins
Authors: Panina Ekaterina M. , Mironov Andrey A. , Gelfand Mikhail S.
Published: August 2003

Zinc is an important component of many proteins, but in large
concentrations it is poisonous to the cell. Thus its transport is regulated by
zinc repressors ZUR of proteobacteria and Gram-positive bacteria from the
Bacillus
group and AdcR of bacteria from the
Streptococcus
group. Comparative computational analysis allowed us to identify binding
signals of ZUR repressors GAAATGTTATA
N
TATAACATTTC for
γ-proteobacteria, GTAATGTA
AT
AACATTAC for the
Agrobacterium
group, GATATGTT
AT
AACATATC for the
Rhododoccus
group, TAAATCGTAAT
N
ATTACGATTTA for
Gram-positive bacteria, and TTAAC
YR
GTTAA of the streptococcal AdcR
repressor. In addition to known transporters and their paralogs, zinc regulons
were predicted to contain a candidate component of the ATP binding cassette,
zinT
(
b1995
in
Escherichia coli
and
yrpE
in
Bacillus subtilis
). Candidate AdcR-binding sites were identified
upstream of genes encoding pneumococcal histidine triad (PHT) proteins from a
number of pathogenic streptococci. Protein functional analysis of this family
suggests that PHT proteins are involved in the invasion process. Finally,
repression by zinc was predicted for genes encoding a variety of paralogs of
ribosomal proteins. The original copies of all these proteins contain
zinc-ribbon motifs and thus likely bind zinc, whereas these motifs are
destroyed in zinc-regulated paralogs. We suggest that the induction of these
paralogs in conditions of zinc starvation leads to their incorporation in a
fraction of ribosomes instead of the original ribosomal proteins; the latter
are then degraded with subsequent release of some zinc for the utilization by
other proteins. Thus we predict a mechanism for maintaining zinc availability
for essential enzymes.
On the interactions between atmospheric radicals and cloud droplets: A molecular picture of the interface
Authors: Shi Qicun , Belair Stephen D. , Francisco Joseph S. , Kais Sabre
Published: August 2003

How gas-phase materials become incorporated with cloud droplets has been an
intriguing subject for decades, and considerable work has been done to
understand the interactions between closed-shell molecules and liquid water.
The interactions between open-shell radical species and liquid-phase cloud
droplets, however, are not well understood. To probe these interactions we
used quantum chemistry calculations to predict the energetics of the
hydroperoxy radical (HO
2
) in the presence of an
(H
2
O)
20
spherical water cage. Our calculations show that
it is energetically favorable for the radical to bind to the outside of the
cage. This configuration has the hydrogen and the terminal oxygen of the
radical as its primary bonding sites. Free-energy calculations suggest that,
at atmospheric conditions, there will be a partitioning between HO
2
radicals that are surface-bound and HO
2
radicals that dissolve into
the bulk. This may have important ramifications for our understanding of
radical chemistry and may lend insight into the role that clouds and aerosols
play in atmospheric chemical processes.
Disruption of type 5 adenylyl cyclase gene preserves cardiac function against pressure overload
Authors: Okumura Satoshi , Takagi Gen , Kawabe Jun-ichi , Yang Guiping , Lee Ming-Chih , Hong Chull , Liu Jing , Vatner Dorothy E. , Sadoshima Junichi , Vatner Stephen F. , Ishikawa Yoshihiro
Published: August 2003

The sympathetic nervous system is designed to respond to stress. Adenylyl
cyclase (AC) is the keystone of sympathetic transmission, yet its role in
response to acute overload in the heart or in the pathogenesis of heart
failure is controversial. We examined the effects of pressure overload,
induced by thoracic aortic banding, in mice in which type 5 AC, a major
cardiac AC isoform, was disrupted
(
AC5
–
/
–
). Left
ventricular weight/tibial length ratio (LVW/TL) was not different between the
WT and
AC5
–
/
–
at
baseline and increased progressively and similarly in both groups at 1 and 3
wk after aortic banding. However, LV ejection fraction (LVEF) fell in WT at 3
wk after banding (from 70 ± 2.8 to 57 ± 3.9%,
P
<
0.05), and this decrease was associated with LV dilatation, indicating
incipient cardiac failure. In contrast,
AC5
–
/
–
mice did not
exhibit a fall in LVEF from 74 ± 2.2%. The number of apoptotic myocytes
was similar at baseline, but it increased roughly 4-fold in WT at both 1 and 3
wk after banding, and significantly less,
P
< 0.05, in
AC5
–
/
–
. Importantly, the
increase in apoptosis occurred before the decline in LVEF in WT. The
protective mechanism seems to involve Bcl-2, which was up-regulated
significantly more in
AC5
–
/
–
mice with
pressure overload. Our findings suggest that limiting type 5 AC plays a
protective role in response to pressure overload and the development of heart
failure, potentially through limiting the incidence of myocardial
apoptosis.
Replication-initiator protein (UL9) of the herpes simplex virus 1 binds NFB42 and is degraded via the ubiquitin–proteasome pathway
Authors: Eom Chi-Yong , Lehman I. Robert
Published: August 2003

The ubiquitin–proteasome pathway plays a critical role in the
degradation of short-lived and regulatory proteins in a variety of cellular
processes. The F-box proteins are part of the ubiquitin–ligase
complexes, which mediate ubiquitination and proteasome-dependent degradation
of phosphorylated proteins. We previously identified NFB42, an F-box protein
that is highly enriched in the nervous system, as a binding partner for the
herpes simplex virus 1 UL9 protein, the viral replication-initiator protein,
in a yeast two-hybrid screen. In the present work, we find that coexpression
of NFB42 and UL9 genes in 293T cells leads to a significant decrease in the
level of UL9 protein. Treatment with the 26S-proteasome inhibitor MG132
restores the UL9 protein to normal levels. We have observed also that the UL9
protein is polyubiquitinated
in vivo
and that the interaction between
NFB42 and the UL9 protein is dependent upon phosphorylation of the UL9
protein. These results suggest that the interaction of the UL9 protein with
NFB42 results in its polyubiquitination and subsequent degradation by the 26S
proteasome. They suggest further a mechanism by which latency of herpes
simplex virus 1 can be established in neuronal cells.
Targeted disruption of
p185/Cul7
gene results in abnormal vascular morphogenesis
Authors: Arai Takehiro , Kasper Jocelyn S. , Skaar Jeffrey R. , Ali Syed Hamid , Takahashi Chiaki , DeCaprio James A.
Published: August 2003

Cul1, a member of the cullin ubiquitin ligase family, forms a multiprotein
complex known as SCF and plays an essential role in numerous cellular and
biological activities. A Cul1 homologue, p185 (Cul7), has been isolated as an
simian virus 40 large T antigen-binding protein. To understand the
physiological role of p185, we generated mice lacking p185.
p185
–
/
–
embryos are
runted and die immediately after birth because of respiratory distress. Dermal
and hypodermal hemorrhage is detected in mutant embryos at late gestational
stage.
p185
–
/
–
placentas
show defects in the differentiation of the trophoblast lineage with an
abnormal vascular structure. We demonstrate that p185 forms an SCF-like
complex with Skp1, Rbx1, Fbw6 (Fbx29), and FAP68 (FAP48, glomulin).
FAP68
has recently been identified as a gene responsible for familial
glomuvenous malformation. These results suggest that p185 forms a multiprotein
complex and plays an important role in vascular morphogenesis.
Protein grafting of an HIV-1-inhibiting epitope
Authors: Sia Samuel K. , Kim Peter S.
Published: August 2003

Protein grafting, the transfer of a binding epitope of one ligand onto the
surface of another protein, is a potentially powerful technique for presenting
peptides in preformed and active three-dimensional conformations. Its utility,
however, has been limited by low biological activity of the designed ligands
and low tolerance of the protein scaffolds to surface substitutions. Here, we
graft the complete binding epitope (19 nonconsecutive amino acids with a
solvent-accessible surface area of >2,000 Å
2
) of an HIV-1
C-peptide, which is derived from the C-terminal region of HIV-1 gp41 and
potently inhibits HIV-1 entry into cells, onto the surface of a GCN4 leucine
zipper. The designed peptide, named C34coil, displays a potent antiviral
activity approaching that of the native ligand. Moreover, whereas the linear
C-peptide is unstructured and sensitive to degradation by proteases, C34coil
is well structured, conformationally stable, and exhibits increased resistance
to proteolytic degradation compared with the linear peptide. In addition to
being a structured antiviral inhibitor, C34coil may also serve as the basis
for the development of an alternative class of immunogens. This study
demonstrates that “one-shot” protein grafting, without subsequent
rounds of optimization, can be used to create ligands with structural
conformations and improved biomedical properties.
Morphogenesis of the telencephalic commissure requires scaffold protein JNK-interacting protein 3 (JIP3)
Authors: Kelkar Nyaya , Delmotte Marie-Helene , Weston Claire R. , Barrett Tamera , Sheppard Barbara J. , Flavell Richard A. , Davis Roger J.
Published: August 2003

The murine JNK-interacting protein 3 (JIP3) protein (also known as JSAP1)
is expressed exclusively in neurons and has been identified as a scaffold
protein for the c-Jun NH
2
-terminal kinase (JNK) signaling pathway
and as an adapter protein for cargo transport by the microtubule motor protein
kinesin. To investigate the physiological function of JIP3, we examined the
effect of
Jip3
gene disruption in mice. The
Jip3
–
/
–
mice were unable
to breathe and died shortly after birth. Microscopic analysis demonstrated
that
Jip3
gene disruption causes severe defects in the morphogenesis
of the telencephalon.
Jip3
–
/
–
mice lack the
telencephalic commissure, a major connection between the left and right
hemispheres of the brain. The central nervous system abnormalities of
Jip3
–
/
–
mice may be
accounted for in part by a reduction in signal transduction by RhoA and its
effector ROCK.
Determination of the protein composition of the occlusion-derived virus of
Autographa californica
nucleopolyhedrovirus
Authors: Braunagel S. C. , Russell W. K. , Rosas-Acosta G. , Russell D. H. , Summers M. D.
Published: August 2003

The occlusion derived form of baculovirus is specially adapted for primary
infection of the host midgut epithelium. As such, the virion must contain the
proteins essential for host range determination and initiation of infection.
Because knowledge of virion composition is a prerequisite for functional
investigation, this study used a combination of techniques to identify the
proteins present within or associated with the occlusion-derived virus (ODV)
virion. Thirty-one proteins, including proteins known to be essential for
viral DNA replication, were identified with confidence. An additional 13
proteins were identified by using one of the three techniques. A comparison of
gene conservation among the ODV proteins encoded in the 16 sequenced
baculoviridae
genomes is presented. With knowledge of the composition
of ODV, it is now possible to target proteins and study their role(s) during
primary infection.
Repression of Smad transcriptional activity by PIASy, an inhibitor of activated STAT
Authors: Long Jianyin , Matsuura Isao , He Dongming , Wang Guannan , Shuai Ke , Liu Fang
Published: August 2003

Smad proteins mediate transforming growth factor β
(TGF-β)-inducible transcriptional responses. Protein inhibitor of
activated signal transducer and activator of transcription (PIAS) represents a
family of proteins that inhibits signal transducer and activator of
transcription and also regulates other transcriptional responses. In an effort
to identify Smad-interacting proteins by a yeast three-hybrid screen with
Smad3 and Smad4 as baits, we identified PIASy, a member of the PIAS family. In
yeast, PIASy interacts strongly with Smad4 and also with receptor-regulated
Smads. In mammalian cells, PIASy binds most strongly with Smad3 and also
associates with other receptor-regulated Smads and Smad4. The interaction
between Smad3 and PIASy is increased in the presence of TGF-β and occurs
through the C-terminal domain of Smad3. Moreover, Smad3, Smad4, and PIASy can
form a ternary complex. PIASy does not inhibit Smad complex binding to DNA,
but it represses Smad transcriptional activity. Interestingly, conditional
overexpression of PIASy selectively inhibits a subset of endogenous
TGF-β-responsive genes, which includes the cyclin-dependent kinase
inhibitor p15, and the plasminogen activator inhibitor 1. We further show that
PIASy can interact constitutively with histone deacetylase 1 (HDAC1) and that
addition of HDAC inhibitor trichostatin A (TSA) can prevent the inhibitory
function of PIASy. Taken together, our studies indicate that PIASy can inhibit
TGF-β/Smad transcriptional responses through interactions with Smad
proteins and HDAC.
A SNARE required for retrograde transport to the endoplasmic reticulum
Authors: Burri Lena , Varlamov Oleg , Doege Claudia A. , Hofmann Kay , Beilharz Traude , Rothman James E. , Söllner Thomas H. , Lithgow Trevor
Published: August 2003

SNAREs (soluble
N
-ethylmaleimide-sensitive factor attachment
protein receptors) are central components of the machinery mediating membrane
fusion in all eukaryotic cells. Sequence analysis of the yeast genome revealed
a previously uncharacterized SNARE,
S
NARE-
l
ike
t
ail-anchored protein 1 (Slt1). Slt1 is an essential protein
localized in the endoplasmic reticulum (ER). It forms a SNARE complex with
Sec22 and the ER syntaxin Ufe1. Down-regulation of Slt1 levels leads to
improper secretion of proteins normally resident in the ER. We suggest that
Slt1 is a component of the SNAREpin required for retrograde traffic to the ER.
Based on the previously reported association with Ufe1 and Sec22, Sec20 likely
contributes the fourth SNARE to the SNAREpin.
Dissociation of amyloid fibrils of α-synuclein and transthyretin by pressure reveals their reversible nature and the formation of water-excluded cavities
Authors: Foguel Débora , Suarez Marisa C. , Ferrão-Gonzales Astria D. , Porto Thais C. R. , Palmieri Leonardo , Einsiedler Carla M. , Andrade Leonardo R. , Lashuel Hilal A. , Lansbury Peter T. , Kelly Jeffery W. , Silva Jerson L.
Published: August 2003

Protein misfolding and aggregation have been linked to several human
diseases, including Alzheimer's disease, Parkinson's disease, and systemic
amyloidosis, by mechanisms that are not yet completely understood. The
hallmark of most of these diseases is the formation of highly ordered and
β-sheet-rich aggregates referred to as amyloid fibrils. Fibril formation
by WT transthyretin (TTR) or TTR variants has been linked to the etiology of
systemic amyloidosis and familial amyloid polyneuropathy, respectively.
Similarly, amyloid fibril formation by α-synuclein (α-syn) has
been linked to neurodegeneration in Parkinson's disease, a movement disorder
characterized by selective degeneration of dopaminergic neurons in the
substantia nigra. Here we show that consecutive cycles of
compression–decompression under aggregating conditions lead to
reversible dissociation of TTR and α-syn fibrils. The high sensitivity
of amyloid fibrils toward high hydrostatic pressure (HHP) indicates the
existence of packing defects in the fibril core. In addition, through the use
of HHP we are able to detect differences in stability between fibrils formed
from WT TTR and the familial amyloidotic polyneuropathy-associated variant
V30M. The fibrils formed by WT α-syn were less susceptible to pressure
denaturation than the Parkinson's disease-linked variants, A30P and A53T. This
finding implies that fibrils of α-syn formed from the variants would be
more easily dissolved into small oligomers by the cellular machinery. This
result has physiological importance in light of the current view that the
pathogenic species are the small aggregates rather the mature fibrils.
Finally, the HHP-induced formation of fibrils from TTR is relatively fast
(≈60 min), a quality that allows screening of antiamyloidogenic drugs.
The phosphatidylinositol (PI)-5-phosphate 4-kinase type II enzyme controls insulin signaling by regulating PI-3,4,5-trisphosphate degradation
Authors: Carricaburu Valerie , Lamia Katja A. , Lo Elizabeth , Favereaux Laetitia , Payrastre Bernard , Cantley Lewis C. , Rameh Lucia E.
Published: August 2003

Phosphatidylinositol-5-phosphate (PI-5-P) is a newly identified
phosphoinositide with characteristics of a signaling lipid but no known
cellular function. PI-5-P levels are controlled by the type II PI-5-P
4-kinases (PIP4K IIs), a family of kinases that converts PI-5-P into
phosphatidylinositol-4,5-bisphosphate (PI-4,5-P
2
). The PI-5-P
pathway is an alternative route for PI-4,5-P
2
synthesis as the bulk
of this lipid is generated by the canonical pathway in which
phosphatidylinositol-4-phosphate (PI-4-P) is the intermediate. Here we
examined the effect of activation of the PI-5-P pathway on phosphoinositide
3-kinase (PI3K) signaling by expressing PIP4K IIβ in cells that lack this
enzyme. Although PIP4K II generates PI-4,5-P
2
, a substrate for
PI3K, expression of this enzyme reduced rather than increased
phosphatidylinositol-3,4,5-trisphosphate (PI-3,4,5-P
3
) levels in
cells stimulated with insulin or cells expressing activated PI3K. This
reduction in PI-3,4,5-P
3
levels resulted in decreased activation of
the downstream protein kinase, Akt/PKB. Consistent with these results,
expression of IpgD, a bacterial phosphatase that converts PI-4,5-P
2
to PI-5-P, resulted in Akt activation, and this effect was partially reversed
by PIP4K IIβ. PIP4K IIβ expression did not impair insulin-dependent
association of PI3K with insulin receptor substrate 1 (IRS1) but abbreviated
Akt activation, indicating that PIP4K II regulates PI-3,4,5-P
3
degradation rather than synthesis. These data support a model in which the
PI-5-P pathway controls insulin signaling that leads to Akt activation by
regulating a PI-3,4,5-P
3
phosphatase.
Long-distance root-to-shoot transport of phytochelatins and cadmium in
Arabidopsis
Authors: Gong Ji-Ming , Lee David A. , Schroeder Julian I.
Published: August 2003

Phytochelatin synthases (PCS) mediate cellular heavy-metal resistance in
plants, fungi, and worms. However, phytochelatins (PCs) are generally
considered to function as intracellular heavy-metal detoxification mechanisms,
and whether long-distance transport of PCs occurs during heavy-metal
detoxification remains unknown. Here, wheat
TaPCS1
cDNA expression
was either targeted to
Arabidopsis
roots with the
Arabidopsis
alcohol dehydrogenase (
Adh
) promoter
(Adh::TaPCS1/
cad1-3
) or ectopically expressed with the cauliflower
mosaic virus 35S promoter (35S::TaPCS1/
cad1-3
) in the PC-deficient
mutant
cad1-3
. Adh::TaPCS1/
cad1-3
and
35S::TaPCS1/
cad1-3
complemented the cadmium, mercury, and arsenic
sensitivities of the
cad1-3
mutant. Northern blot, RT-PCR, and
Western blot analyses showed
Adh
promoter-driven TaPCS1 expression
only in roots and thus demonstrated lack of long-distance
TaPCS1
mRNA
and protein transport in plants. Fluorescence HPLC analyses showed that under
Cd
2
+
stress, no PCs were detectable in
cad1
-
3
. However, in Adh::TaPCS1/
cad1-3
plants, PCs
were detected in roots and in rosette leaves and stems. Inductively coupled
plasma atomic emission spectrometer analyses showed that either root-specific
or ectopic expression of
TaPCS1
significantly enhanced long-distance
Cd
2
+
transport into stems and rosette leaves.
Unexpectedly, transgenic expression of TaPCS1 reduced
Cd
2
+
accumulation in roots compared with
cad1-3
. The reduced Cd
2
+
accumulation in roots
and enhanced root-to-shoot Cd
2
+
transport in transgenic
plants were abrogated by
l
-buthionine sulfoximine. The presented
findings show that (
i
) transgenic expression of TaPCS1 suppresses the
heavy-metal sensitivity of
cad1-3
, (
ii
) PCs can be
transported from roots to shoots, and (
iii
) transgenic expression of
the
TaPCS1
gene increases long-distance root-to-shoot
Cd
2
+
transport and reduces Cd
2
+
accumulation in roots.
Induction of sensory long-term facilitation in the carotid body by intermittent hypoxia: Implications for recurrent apneas
Authors: Peng Ying-Jie , Overholt Jeffrey L. , Kline David , Kumar Ganesh K. , Prabhakar Nanduri R.
Published: August 2003

Reflexes from the carotid body have been implicated in cardiorespiratory
disorders associated with chronic intermittent hypoxia (CIH). To investigate
whether CIH causes functional and/or structural plasticity in the carotid
body, rats were subjected to 10 days of recurrent hypoxia or normoxia. Acute
exposures to 10 episodes of hypoxia evoked long-term facilitation (LTF) of
carotid body sensory activity in CIH-conditioned but not in control animals.
The magnitude of sensory LTF depended on the length of CIH conditioning and
was completely reversible and unique to CIH, because conditioning with a
comparable duration of sustained hypoxia was ineffective. Histological
analysis revealed no differences in carotid body morphology between control
and CIH animals. Previous treatment with superoxide anion
(

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) scavenger prevented
sensory LTF. In the CIH-conditioned animals, carotid body aconitase enzyme
activity decreased compared with controls. These observations suggest that
increased generation of reactive oxygen species contribute to sensory LTF. In
CIH animals, carotid body complex I activity of the mitochondrial electron
transport is inhibited, suggesting mitochondria as one source of

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generation. These
observations demonstrate that CIH induces a previously uncharacterized form of
reactive oxygen species-dependent, reversible, functional plasticity in
carotid body sensory activity. The sensory LTF may contribute to persistent
reflex activation of sympathetic nerve activity and blood pressure in
recurrent apnea patients experiencing CIH.
High concentrations of long interspersed nuclear element sequence distinguish monoallelically expressed genes
Authors: Allen Elena , Horvath Steve , Tong Frances , Kraft Peter , Spiteri Elizabeth , Riggs Arthur D. , Marahrens York
Published: August 2003

Genes subject to monoallelic expression are expressed from only one of the two alleles either selected at random (random monoallelic genes) or in a parent-of-origin specific manner (imprinted genes). Because high densities of long interspersed nuclear element (LINE)-1 transposon sequence have been implicated in X-inactivation, we asked whether monoallelically expressed autosomal genes are also flanked by high densities of LINE-1 sequence. A statistical analysis of repeat content in the regions surrounding monoallelically and biallelically expressed genes revealed that random monoallelic genes were flanked by significantly higher densities of LINE-1 sequence, evolutionarily more recent and less truncated LINE-1 elements, fewer CpG islands, and fewer base-pairs of short interspersed nuclear elements (SINEs) sequence than biallelically expressed genes. Random monoallelic and imprinted genes were pooled and subjected to a clustering analysis algorithm, which found two clusters on the basis of aforementioned sequence characteristics. Interestingly, these clusters did not follow the random monoallelic vs. imprinted classifications. We infer that chromosomal sequence context plays a role in monoallelic gene expression and may involve the recognition of long repeats or other features. The sequence characteristics that distinguished the high-LINE-1 category were used to identify more than 1,000 additional genes from the human and mouse genomes as candidate genes for monoallelic expression.
A nuclear target for interleukin-1α: Interaction with the growth suppressor necdin modulates proliferation and collagen expression
Authors: Hu Bo , Wang Shuhui , Zhang Yingze , Feghali Carol A. , Dingman Jeffrey R. , Wright Timothy M.
Published: August 2003

There is growing evidence for the intracellular role of cytokines and
growth factors, but the pathways by which these activities occur remain
largely obscure. Previous work from our laboratory identified the
constitutive, aberrant expression of the 31-kDa IL-1α precursor
(pre-IL-1α) in the nuclei of fibroblasts from the lesional skin of
patients with systemic sclerosis (SSc). We established that pre-IL-1α
expression was associated with increased fibroblast proliferation and collagen
production. Further investigation has led to the identification of a mechanism
by which nuclear expression of pre-IL-1α affects fibroblast growth and
matrix production. By using a yeast two-hybrid method, we found that
pre-IL-1α binds necdin, a nuclear protein with growth suppressor
activity. We mapped the region of pre-IL-1α responsible for necdin
binding and found it to be localized near the N terminus, a region that is
present on pre-IL-1α, but not the mature 17-kDa cytokine. Expression
studies demonstrated that pre-IL-1α associates with necdin in the nuclei
of mammalian cell lines and regulates cell growth and collagen expression. Our
results provide the first evidence, to our knowledge, of a nuclear target for
pre-IL-1α. Based on these findings, we propose that the constitutively
up-regulated expression of pre-IL-1α in the nuclei of SSc fibroblasts
up-regulates proliferation and matrix production of SSc fibroblasts through
binding necdin, and by counteracting its effects on cell growth and collagen
production.
The life cycle of Reticulitermes spp. (Isoptera: Rhinotermitidae): what do we know?
Authors: Lainé L.V. , Wright D.J.
Published: August 2003

The subterranean termites in the genus Reticulitermes have a complex and plastic life cycle, which has been the subject of a number of publications over the past century. Given the inherent difficulties in studying such cryptic, eusocial organisms it is not perhaps surprising that the literature on their biology has failed to reach a consensus. An overview of the literature is given, which is followed by a discussion of the various theories on the life cycle of Reticulitermes spp. A substantial proportion of the review focuses on the French literature, which constitutes the majority of the primary sources and can be difficult to access. There are many discrepancies in the literature in terms of the number of instars, the definition of workers and the question of whether they should be termed pseudergates or, potentially, an additional terminology used to differentiate between pseudergates and the true workers seen in the higher termites (Isoptera: Termitidae). It remains very difficult to compare publications as there is little conformity; a problem that is aggravated by a general absence of drawings of the relevant instars. Further work on the biology of Reticulitermes is clearly required. There is also a need for researchers to agree on a standard terminology for this genus. A glossary is provided for the various synonyms and definitions.
Incidence of insecticide resistance alleles in sexually-reproducing populations of the peach–potato aphid Myzus persicae (Hemiptera: Aphididae) from southern France
Authors: Guillemaud T. , Brun A. , Anthony N. , Sauge M.H. , Boll R. , Delorme R. , Fournier D. , Lapchin L. , Vanlerberghe-Masutti F.
Published: August 2003

Intensive chemical treatments have led to the development of a number of insecticide resistance mechanisms in the peach–potato aphid Myzus persicae (Sulzer). Some of these mechanisms are known to be associated with negative pleiotropic effects (resistance costs). Molecular and biochemical methods were used to determine the genotypes or phenotypes associated with four insecticide resistance mechanisms in single aphids from sexually-reproducing populations in southern France. The mechanisms considered were E4 and FE4 carboxylesterase overproduction, modified acetycholinesterase, and kdr and rdl resistance-associated mutations. A new method for determining individual kdr genotypes is presented. Almost all resistant individuals overproduced FE4 carboxylesterase, whereas modified acetylcholinesterase was rare. Both the kdr and rdl resistance mutations were present at high frequencies in French sexually-reproducing populations. The frequencies of insecticide resistance genes were compared before and after sexual reproduction in one peach orchard at Avignon to evaluate the potential impact of selection on the persistence of resistance alleles in the over-wintering phase. The frequencies of the kdr and rdl mutations varied significantly between autumn and spring sampling periods. The frequency of the kdr mutation increased, probably due to pyrethroid treatments at the end of the winter. Conversely, the frequency of the rdl mutation decreased significantly during winter, probably because of a fitness cost associated with this mutation.
The effect of chrysanthemum leaf trichome density and prey spatial distribution on predation of Tetranychus urticae (Acari: Tetranychidae) by Phytoseiulus persimilis (Acari: Phytoseiidae)
Authors: Stavrinides M.C. , Skirvin D.J.
Published: August 2003

The effect of plant architecture, in terms of leaf hairiness, and prey spatial arrangement, on predation rate of eggs of the spider mite, Tetranychus urticae Koch, by the predatory mite Phytoseiulus persimilis Athias-Henriot was examined on cut stems of chrysanthemums. Three levels of leaf hairiness (trichome density) were obtained using two different chrysanthemum cultivars and two ages within one of the cultivars. The number of prey consumed by P. persimilis was inversely related to trichome density. At low prey densities (less than ten eggs per stem), prey consumption did not differ in a biologically meaningful way between treatments. The effect of prey spatial arrangement on the predation rate of P. persimilis was also examined. Predation rates were higher in prey patches on leaves adjacent to the release point of P. persimilis, but significantly greater numbers of prey were consumed in higher density prey patches compared to low density patches. The predators exhibited non-random searching behaviour, spending more time on leaves closest to the release point. The implications of these findings for biological control and predator–prey dynamics are discussed.
Patterns of resistance to three cereal aphids among wheats in the genus Triticum (Poaceae)
Authors: Migui S.M. , Lamb R.J.
Published: August 2003

Forty-one accessions of wild and cultivated wheats belonging to 19 Triticum species were tested in the field for resistance to three species of aphids, Rhopalosiphum padi Linnaeus, Sitobion avenae Fabricius and Schizaphis graminum Rondani. Antibiotic resistance was estimated by the increase in biomass of aphids over 21 days on adult plants. Overall resistance was estimated by the plant biomass lost due to aphid infestation. All three species of aphids survived and reproduced on all wheats, and reduced spike biomass compared to uninfested controls. The level of antibiosis varied among wheat species and among accessions, with accessions from three, five and one species showing antibiosis to R. padi, S. avenae and S. graminum, respectively. Overall resistance to the three aphid species was observed in five to seven accessions per aphid species. Resistance was usually specific to one aphid species. The frequency of accessions with antibiosis or overall resistance was associated with the ploidy level of the plant species. Except for overall resistance to R. padi, resistance was highest for diploid species and lowest for hexaploid species. No consistent relationship between resistance and level of domestication was detected. Accessions of the wild wheats, Triticum boeoticum Bois, Triticum tauschii (Coss.) Schmal. and Triticum araraticum Jakubz. exhibited high levels of resistance to aphids, as did Triticum monococcum L. which is derived from T. boeoticum. Nevertheless, individual susceptible or resistant accessions occurred at all levels within the evolutionary tree of wheat.
Biological control of the larger grain borer Prostephanus truncatus (Coleoptera: Bostrichidae) in Kenya using a predatory beetle Teretrius nigrescens(Coleoptera: Histeridae)
Authors: Hill M.G. , Nang'ayo F.L.O. , Wright D.J.
Published: August 2003

The establishment of the predatory histerid beetle, Teretrius nigrescens Lewis, following its field release in south eastern Kenya in 1992, and its impact on populations of the larger grain borer, Prostephanus truncatus (Horn), in woodland habitats is evaluated. Pheromone trap catch data show a single strong peak of P. truncatus from November to January, coincident with the short rains. Comparisons of P. truncatus pheromone trap catches before and after predator establishment, and in areas with and without T. nigrescens, show a sustained decline of over 80% in P. truncatus abundance over a 5-year period, following the establishment T. nigrescens. Concurrent laboratory studies of the impact of T. nigrescens on populations of P. truncatus raised on a wood substrate showed a 77% reduction in the growth of the pest population. These results are compared with published findings of the impact of T. nigrescens as a biological control agent of P. truncatus in west Africa.
Response of female Cydia molesta (Lepidoptera: Tortricidae) to plant derived volatiles
Authors: Natale D. , Mattiacci L. , Hern A. , Pasqualini E. , Dorn S.
Published: August 2003

Peach shoot volatiles were attractive to mated female oriental fruit moth, Cydia molesta (Busck), in a dual choice arena. No preference was observed between leaf odours from the principle host plant, peach, and the secondary host plant, apple. Twenty-two compounds were identified in headspace volatiles of peach shoots using gas chromatography–mass spectrometry. Green leaf volatiles accounted for more than 50% of the total emitted volatiles. A bioassay-assisted fractionation using different sorbent polymers indicated an attractant effect of compounds with a chain length of 6–8 carbon atoms. The major compounds of this fraction were tested either singly or in combinations for behavioural response of females. Significant bioactivity was found for a three-component mixture of (Z)-3-hexen-1-yl acetate, (Z)-3-hexen-1-ol and benzaldehyde in a 4:1:1 ratio. This synthetic mixture elicited a similar attractant effect as the full natural blend from peach shoots as well as the bioactive fraction.
Visualization of chromatin domains created by the gypsy insulator of Drosophila
Authors: Byrd Keith , Corces Victor G.
Published: August 2003

Insulators might regulate gene expression by establishing and maintaining the organization of the chromatin fiber within the nucleus. Biochemical fractionation and in situ high salt extraction of lysed cells show that two known protein components of the gypsy insulator are present in the nuclear matrix. Using FISH with DNA probes located between two endogenous Su(Hw) binding sites, we show that the intervening DNA is arranged in a loop, with the two insulators located at the base. Mutations in insulator proteins, subjecting the cells to a brief heat shock, or destruction of the nuclear matrix lead to disruption of the loop. Insertion of an additional gypsy insulator in the center of the loop results in the formation of paired loops through the attachment of the inserted sequences to the nuclear matrix. These results suggest that the gypsy insulator might establish higher-order domains of chromatin structure and regulate nuclear organization by tethering the DNA to the nuclear matrix and creating chromatin loops.
Association of the RENT complex with nontranscribed and coding regions of rDNA and a regional requirement for the replication fork block protein Fob1 in rDNA silencing
Authors: Huang Julie , Moazed Danesh
Published: August 2003

Silencing within the yeast rDNA repeats inhibits hyperrecombination, represses transcription from foreign promoters, and extends replicative life span. rDNA silencing is mediated by a Sir2-containing complex called RENT (regulator ofnucleolar silencing andtelophase exit). We show that the Net1 (also called Cfi1) and Sir2 subunits of RENT localize primarily to two distinct regions within rDNA: in one of the nontranscribed spacers (NTS1) and around the Pol I promoter, extending into the 35S rRNA coding region. Binding to NTS1 overlaps the recombination hotspot and replication fork barrier elements, which have been shown previously to require the Fob1 protein for their activities. In cells lacking Fob1, silencing and the association of RENT subunits are abolished specifically at NTS1, while silencing and association at the Pol I promoter region are unaffected or increased. We find that Net1 and Sir2 are physically associated with Fob1 and subunits of RNA polymerase I. Together with the localization data, these results suggest the existence of two distinct modes for the recruitment of the RENT complex to rDNA and reveal a role for Fob1 in rDNA silencing and in the recruitment of the RENT complex. Furthermore, the Fob1-dependent associations of Net1 and Sir2 with the recombination hotspot region strongly suggest that Sir2 acts directly at this region to carry out its inhibitory effect on rDNA recombination and accelerated aging.
Identification of a DNA-binding site and transcriptional target for the EWS–WT1(+KTS) oncoprotein
Authors: Reynolds Paul A. , Smolen Gromoslaw A. , Palmer Rachel E. , Sgroi Dennis , Yajnik Vijay , Gerald William L. , Haber Daniel A.
Published: August 2003

Desmoplastic small round cell tumor (DSRCT) is defined by a chimeric transcription factor, resulting from fusion of the N-terminal domain of the Ewing's sarcoma geneEWSto the three C-terminal zinc fingers of the Wilms' tumor suppressorWT1. Although DNA-binding sites have been defined for the uninterruptedWT1zinc finger domains, the most prevalent isoforms of both WT1 and EWS–WT1 have an insertion of three amino acids [lysine, threonine, and serine (KTS)], which abrogates binding to known consensus sequences and transactivation of known target genes. Here, we used cDNA subtractive hybridization to identify an endogenous gene,LRRC15, which is specifically up-regulated after inducible expression ofEWS–WT1(+KTS)in cancer cell lines, and is expressed within primary DSRCT cells. The chimeric protein binds in vitro and in vivo to a specific element upstream ofLRRC15, leading to dramatic transcriptional activation. Mutagenesis studies define the optimal binding site of the (+KTS) isoform of EWS–WT1 as 5′-GGAGG(A/G)-3′.LRRC15encodes a leucine-rich transmembrane protein, present at the leading edge of migrating cells, the expression of which in normal tissues is restricted to the invasive cytotrophoblast layer of the placenta; small interfering (siRNA)-mediated suppression ofLRRC15expression in breast cancer cells leads to abrogation of invasiveness in vitro. Together, these observations define the consequence of (KTS) insertion within WT1-derived zinc fingers, and identify a novel EWS–WT1 transcriptional target implicated in tumor invasiveness.
GATA-3: an unexpected regulator of cell lineage determination in skin
Authors: Kaufman Charles K. , Zhou Ping , Amalia Pasolli H. , Rendl Michael , Bolotin Diana , Lim Kim-Chew , Dai Xing , Alegre Maria-Luisa , Fuchs Elaine
Published: August 2003

Multipotent skin stem cells give rise to epidermis and its appendages, including the hair follicle. The Lef-1/Tcf family of Wnt-regulated transcription factors plays a major role in specification of the hair shaft, but little is known about how the equally important hair channel, the inner root sheath (IRS), develops in concert to shape and guide the hair. In a microarray screen to search for transcriptional regulators of hair follicle morphogenesis, we identified GATA-3, a key regulator of T-cell lineage determination. Surprisingly, this transcription factor is essential for stem cell lineage determination in skin, where it is expressed at the onset of epidermal stratification and IRS specification in follicles.GATA-3-null/lacZknock-in embryos can survive up to embryonic day 18.5 (E18.5), when they fail to form the IRS. Skin grafting unveiled additional defects inGATA-3-null hairs and follicles. IRS progenitors failed to differentiate, whereas cortical progenitors differentiated, but produced an aberrant hair structure. Curiously, someGATA-3-null progenitor cells expressed mixed IRS and hair shaft markers. Taken together, these findings place GATA-3 with Lef-1/Wnts at the crossroads of the IRS versus hair shaft cell fate decision in hair follicle morphogenesis. This newfound function for GATA-3 in skin development strengthens the parallels between the differentiation programs governing hair follicle and lymphocyte differentiation.
Heritable activity: a prion that propagates by covalent autoactivation
Authors: Roberts B.Tibor , Wickner Reed B.
Published: August 2003

Known prions (infectious proteins) are self-propagating amyloids or conformationally altered proteins, but in theory an enzyme necessary for its own activation could also be a prion (or a gene composed of protein).We show that yeast protease B is such a prion, called [β].[β] is infectious, reversibly curable, and its de novo generation is induced by overexpression of the pro-protease. Present in normal cells but masked by the functionally redundant protease A, [β] is advantageous during starvation and necessary for sporulation.We propose that other enzymes whose active, modified, form is necessary for their maturation might also be prions.
Theknotted1-like homeobox geneBREVIPEDICELLUSregulates cell differentiation by modulating metabolic pathways
Authors: Mele Giovanni , Ori Naomi , Sato Yutaka , Hake Sarah
Published: August 2003

Members of theKNOXgene family have important roles in plant meristems by regulating cell division and differentiation.BREVIPEDICELLUS(BP), one of sevenKNOXgenes inArabidopsis, has a primary role in internode patterning. We carried out a comparison of RNA expression profiles between wild-type seedlings andbpmutants at a developmental stage prior to a visible phenotypic difference. Transcript differences were found for a number of genes in cell wall biosynthesis, especially genes in the lignin pathway. The regulation of lignin biosynthesis byBPwas demonstrated by observing increased lignin deposition inbpmutants following bolting, decreased lignification in plants overexpressingBP, and aberrant lignin deposition in discrete regions of thebpstem. Furthermore, we showed that BP binds promoters of some genes in the lignin pathway. Our results provide a metabolic fingerprint forBPand identify the lignin pathway as one of the coordinate processes thatBPregulates.
Identification of the C-signal, a contact-dependent morphogen coordinating multiple developmental responses inMyxococcus xanthus
Authors: Lobedanz Sune , Søgaard-Andersen Lotte
Published: August 2003

The regulated accumulation of the contact-dependent extracellular C-signal morphogen in the bacteriumMyxococcus xanthusensures the temporal and spatial coordination of multicellular morphogenesis and cellular differentiation during fruiting bodyformation. Synthesis of the C-signal depends on thecsgAgene. The CsgA protein exists in two forms, the full-length 25-kD protein (p25), which is homologous to short-chain alcohol dehydrogenases, and a 17-kD protein (p17). The molecular nature of the C-signal has remained elusive. Here we show that p25 and p17 are associated with the outer membrane and that p17 copurifies with C-signal activityfromM. xanthuscells. p17 corresponds to the C-terminal part of p25. A recombinant p17 protein, which lacks the N-terminal coenzyme binding pocket and which fails to bind NAD+in vitro, has C-signal activity. These data provide evidence that p17 is the active species in C-signaling and that p17 does not act as a short-chain alcohol dehydrogenase to generate the C-signal. We further provide evidence that p17 is synthesized by N-terminal proteolytic processing of p25 by a serine protease. Compared to other bacterial signaling molecules, p17 is unusual with respect to size and cell-surface association. In these regards, C-signal is functionally analogous to eukaryotic signaling proteins.
Locating Sequence on FPC Maps and Selecting a Minimal Tiling Path
Authors: Engler Friedrich W. , Hatfield James , Nelson William , Soderlund Carol A.
Published: August 2003

This study discusses three software tools, the first two aid in integrating sequence with an FPC physical map and the third automatically selects a minimal tiling path given genomic draft sequence and BAC end sequences. The first tool, FSD (FPC Simulated Digest), takes a sequenced clone and adds it back to the map based on a fingerprint generated by an in silico digest of the clone. This allows verification of sequenced clone positions and the integration of sequenced clones that were not originally part of the FPC map. The second tool, BSS (Blast Some Sequence), takes a query sequence and positions it on the map based on sequence associated with the clones in the map. BSS has multiple uses as follows: (1) When the query is a file of marker sequences, they can be added as electronic markers. (2) When the query is draft sequence, the results of BSS can be used to close gaps in a sequenced clone or the physical map. (3) When the query is a sequenced clone and the target is BAC end sequences, one may select the next clone for sequencing using both sequence comparison results and map location. (4) When the query is whole-genome draft sequence and the target is BAC end sequences, the results can be used to select many clones for a minimal tiling path at once. The third tool, pickMTP, automates the majority of this last usage of BSS. Results are presented using the rice FPC map, BAC end sequences, and whole-genome shotgun from Syngenta.