bluuebunny/crossref_metadata_2025 huggingface dataset:
A method for assaying intestinal brush-border sucrase in an intact intestinal preparation
Authors: Lee Eric A. , Weiss Stacey L. , Lam Mandy , Torres Rosa , Diamond Jared
Published: July 2002

Small intestinal brush-border hydrolases usually are assayed in intestinal mucosal homogenates resuspended in solutions of unphysiological ionic composition. Thus, extrapolation of measured
V
max
values (maximal reaction rates at high substrate concentrations) to
in vivo
conditions, hence comparison with physiological substrate loads, is uncertain. We therefore have developed a sucrase assay in an intact preparation of mouse small intestine, an everted intestinal sleeve incubated in a physiological Ringer’s solution. As in homogenate studies, sucrase is assayed by glucose production measured colorimetrically, but uptake of liberated glucose into the intestinal sleeve is prevented by the transport inhibitor phlorizin. The coefficient of variation of
V
max
is 16% for sleeves from the same mouse and 8% for mean values from different mice. Sleeve sucrase activity is abolished by the inhibitor castanospermine. Activity in sleeves and homogenates proves to be the same when measured under identical solution conditions, but variations in assay conditions cause large activity changes from values measured in physiological solutions.
Functional anatomy of musical processing in listeners with absolute pitch and relative pitch
Authors: Zatorre Robert J. , Perry David W. , Beckett Christine A. , Westbury Christopher F. , Evans Alan C.
Published: July 2002

We used both structural and functional brain imaging techniques to investigate the neural basis of absolute pitch (AP), a specialized skill present in some musicians. By using positron emission tomography, we measured cerebral blood flow during the presentation of musical tones to AP possessors and to control musicians without AP. Listening to musical tones resulted in similar patterns of increased cerebral blood flow in auditory cortical areas in both groups, as expected. The AP group also demonstrated activation of the left posterior dorsolateral frontal cortex, an area thought to be related to learning conditional associations. However, a similar pattern of left dorsolateral frontal activity was also observed in non-AP subjects when they made relative pitch judgments of intervals, such as minor or major. Conversely, activity within the right inferior frontal cortex was observed in control but not in AP subjects during the interval-judgment task, suggesting that AP possessors need not access working memory mechanisms in this task. MRI measures of cortical volume indicated a larger left planum temporale in the AP group, which correlated with performance on an pitch-naming task. Our findings suggest that AP may not be associated with a unique pattern of cerebral activity but rather may depend on the recruitment of a specialized network involved in the retrieval and manipulation of verbal–tonal associations.
Statistical analysis of shape through triangulation of landmarks: A study of sexual dimorphism in hominids
Authors: Rao Calyampudi R. , Suryawanshi Shailaja
Published: July 2002

Two objects with homologous landmarks are said to be of the same shape if the configuration of landmarks of one object can be exactly matched with that of the other by translation, rotation/reflection, and scaling. In an earlier paper, the authors proposed statistical analysis of shape by considering logarithmic differences of all possible Euclidean distances between landmarks. Tests of significance for differences in the shape of objects and methods of discrimination between populations were developed with such data. In the present paper, the corresponding statistical methodology is developed by triangulation of the landmarks and by considering the angles as natural measurements of shape. This method is applied to the study of sexual dimorphism in hominids.
When defense backfires: Detrimental effect of a plant’s protective trichomes on an insect beneficial to the plant
Authors: Eisner Thomas , Eisner Maria , Hoebeke E. Richard
Published: July 2002

The plantMentzelia pumila(family Loasaceae) has leaves and stems densely covered with tiny hooked trichomes. The structures entrap and kill insects and therefore are most probably protective. But they are also maladaptive in that they incapacitate a coccinellid beetle (Hippodamia convergens) that preys upon an aphid enemy (Macrosiphum mentzeliae) of the plant. The adaptive benefit provided by the trichomes is evidently offset by a cost.
Malaria’s Eve: Evidence of a recent population bottleneck throughout the world populations of
Plasmodium falciparum
Authors: Rich Stephen M. , Licht Monica C. , Hudson Richard R. , Ayala Francisco J.
Published: July 2002

We have analyzed DNA sequences from world-wide geographic strains of
Plasmodium falciparum
and found a complete absence of synonymous DNA polymorphism at 10 gene loci. We hypothesize that all extant world populations of the parasite have recently derived (within several thousand years) from a single ancestral strain. The upper limit of the 95% confidence interval for the time when this most recent common ancestor lived is between 24,500 and 57,500 years ago (depending on different estimates of the nucleotide substitution rate); the actual time is likely to be much more recent. The recent origin of the
P. falciparum
populations could have resulted from either a demographic sweep (
P. falciparum
has only recently spread throughout the world from a small geographically confined population) or a selective sweep (one strain favored by natural selection has recently replaced all others). The selective sweep hypothesis requires that populations of
P. falciparum
be effectively clonal, despite the obligate sexual stage of the parasite life cycle. A demographic sweep that started several thousand years ago is consistent with worldwide climatic changes ensuing the last glaciation, increased anthropophilia of the mosquito vectors, and the spread of agriculture.
P. falciparum
may have rapidly spread from its African tropical origins to the tropical and subtropical regions of the world only within the last 6,000 years. The recent origin of the world-wide
P. falciparum
populations may account for its virulence, as the most malignant of human malarial parasites.
Identification and characterization of the
ARP1
gene, a target for the human acute leukemia
ALL1
gene
Authors: Arakawa Hirofumi , Nakamura Tatsuya , Zhadanov Alexander B. , Fidanza Vincenzo , Yano Takahiro , Bullrich Florencia , Shimizu Masayoshi , Blechman Janna , Mazo Alexander , Canaani Eli , Croce Carlo M.
Published: July 2002

ALL1
, the human homologue of Drosophila
trithorax
, is directly involved in human acute leukemias associated with abnormalities at 11q23. Using the differential display method, we isolated a gene that is down-regulated in
All1
double-knockout mouse embryonic stem (ES) cells. The gene, designated
ARP1
(also termed
RIEG
,
Ptx2
, or
Otlx2
), is a member of a family of homeotic genes containing a short motif shared with several homeobox genes. Using a bacterially synthesized All1 polypeptide encompassing the AT-hook motifs, we identified a 0.5-kb
ARP1
DNA fragment that preferentially bound to the polypeptide. Within this DNA, a region of ≈100 bp was protected by the polypeptide from digestion with
Exo
III and DNase I. Whole-mount
in situ
hybridization to early mouse embryos of 9.5–10.5 days indicated a complex pattern of
Arp1
expression spatially overlapping with the expression of
All1
. Although the
ARP1
gene is expressed strongly in bone marrow cells, no transcripts were detected in six leukemia cell lines with 11q23 translocations. These results suggest that
ARP1
is up-regulated by the All1 protein, possibly through direct interaction with an upstream DNA sequence of the former. The results are also consistent with the suggestion that
ALL1
chimeric proteins resulting from 11q23 abnormalities act in a dominant negative fashion.
Nuclear endpoint of Wnt signaling: Neoplastic transformation induced by transactivating lymphoid-enhancing factor 1
Authors: Aoki Masahiro , Hecht Andreas , Kruse Ulrich , Kemler Rolf , Vogt Peter K.
Published: July 2002

The interaction between β-catenin and LEF-1/TCF transcription factors plays a pivotal role in the Wnt-1 signaling pathway. The level of β-catenin is regulated by partner proteins, including glycogen synthase kinase-3β (GSK-3β) and the adenomatous polyposis coli (APC) tumor suppressor protein. Genetic defects in APC are responsible for a heritable predisposition to colon cancer. APC protein and GSK-3β bind β-catenin, retain it in the cytoplasm, and facilitate the proteolytic degradation of β-catenin. Abrogation of this negative regulation allows β-catenin to translocate to the nucleus and to form a transcriptional activator complex with the DNA-binding protein lymphoid-enhancing factor 1 (LEF-1). This complex is thought to be involved in tumorigenesis. Here we show that covalent linkage of LEF-1 to β-catenin and to transcriptional activation domains derived from the estrogen receptor or the herpes simplex virus protein VP16 generates transcriptional regulators that induce oncogenic transformation of chicken embryo fibroblasts. The chimeras between LEF-1 and β-catenin or VP16 are constitutively active, whereas fusions of LEF-1 to the estrogen receptor are regulatable by estrogen. These experiments document the oncogenicity of transactivating LEF-1 and show that the transactivation domain normally provided by β-catenin can be replaced by heterologous activation domains. These results suggest that the transactivating function of the LEF-1/β-catenin complex is critical for tumorigenesis and that this complex transforms cells by activating specific LEF-1 target genes.
Virus-specific immunity after gene therapy in a murine model of severe combined immunodeficiency
Authors: Bunting Kevin D. , Flynn Kirsten J. , Riberdy Janice M. , Doherty Peter C. , Sorrentino Brian P.
Published: July 2002

Human severe combined immunodeficiency (SCID) can be caused by defects in Janus kinase 3 (JAK3)-dependent cytokine signaling pathways. As a result, patients are at high risk of life-threatening infection. A JAK3 −/− SCID mouse model for the human disease has been used to test whether transplant with retrovirally transduced bone marrow (BM) cells (JAK3 BMT) could restore immunity to an influenza A virus. The immune responses also were compared directly with those for mice transplanted with wild-type BM (+/+ BMT). After infection, approximately 90% of the JAK3 BMT or +/+ BMT mice survived, whereas all of the JAK3 −/− mice died within 29 days. Normal levels of influenza-specific IgG were present in plasma from JAK3 BMT mice at 14 days after respiratory challenge, indicating restoration of B cell function. Influenza-specific CD4+and CD8+T cells were detected in the spleen and lymph nodes, and virus-specific CD8+effectors localized to the lungs of the JAK3 BMT mice. The kinetics of the specific host response correlated with complete clearance of the virus within 2 weeks of the initial exposure. By contrast, the JAK3 −/− mice did not show any evidence of viral immunity and were unable to control this viral pneumonia. Retroviral-mediated JAK3 gene transfer thus restores diverse aspects of cellular and humoral immunity and has obvious potential for human autologous BMT.
Increased mortality, hypoactivity, and hypoalgesia in cannabinoid CB1 receptor knockout mice
Authors: Zimmer Andreas , Zimmer Anne M. , Hohmann Andrea G. , Herkenham Miles , Bonner Tom I.
Published: July 2002

Δ
9
-Tetrahydrocannabinol (Δ
9
-THC), the major psychoactive ingredient in preparations of
Cannabis sativa
(marijuana, hashish), elicits central nervous system (CNS) responses, including cognitive alterations and euphoria. These responses account for the abuse potential of cannabis, while other effects such as analgesia suggest potential medicinal applications. To study the role of the major known target of cannabinoids in the CNS, the CB1 cannabinoid receptor, we have produced a mouse strain with a disrupted CB1 gene. CB1 knockout mice appeared healthy and fertile, but they had a significantly increased mortality rate. They also displayed reduced locomotor activity, increased ring catalepsy, and hypoalgesia in hotplate and formalin tests. Δ
9
-THC-induced ring-catalepsy, hypomobility, and hypothermia were completely absent in CB1 mutant mice. In contrast, we still found Δ
9
-THC-induced analgesia in the tail-flick test and other behavioral (licking of the abdomen) and physiological (diarrhea) responses after Δ
9
-THC administration. Thus, most, but not all, CNS effects of Δ
9
-THC are mediated by the CB1 receptor.
Ecological approaches and the development of “truly integrated” pest management
Authors: Thomas Matthew B.
Published: July 2002

Recent predictions of growth in human populations and food supply suggest that there will be a need to substantially increase food production in the near future. One possible approach to meeting this demand, at least in part, is the control of pests and diseases, which currently cause a 30–40% loss in available crop production. In recent years, strategies for controlling pests and diseases have tended to focus on short-term, single-technology interventions, particularly chemical pesticides. This model frequently applies even where so-called integrated pest management strategies are used because in reality, these often are dominated by single technologies (e.g., biocontrol, host plant resistance, or biopesticides) that are used as replacements for chemicals. Very little attention is given to the interaction or compatibility of the different technologies used. Unfortunately, evidence suggests that such approaches rarely yield satisfactory results and are unlikely to provide sustainable pest control solutions for the future. Drawing on two case histories, this paper demonstrates that by increasing our basic understanding of how individual pest control technologies act and interact, new opportunities for improving pest control can be revealed. This approach stresses the need to break away from the existing single-technology, pesticide-dominated paradigm and to adopt a more ecological approach built around a fundamental understanding of population biology at the local farm level and the true integration of renewable technologies such as host plant resistance and natural biological control, which are available to even the most resource-poor farmers.
Ecological intensification of cereal production systems: Yield potential, soil quality, and precision agriculture
Authors: Cassman Kenneth G.
Published: July 2002

Wheat (
Triticum aestivum
L.), rice (
Oryza
sativa
L.), and maize (
Zea mays
L.) provide about
two-thirds of all energy in human diets, and four major cropping
systems in which these cereals are grown represent the foundation of
human food supply. Yield per unit time and land has increased markedly
during the past 30 years in these systems, a result of intensified crop
management involving improved germplasm, greater inputs of fertilizer,
production of two or more crops per year on the same piece of land, and
irrigation. Meeting future food demand while minimizing expansion of
cultivated area primarily will depend on continued intensification of
these same four systems. The manner in which further intensification is
achieved, however, will differ markedly from the past because the
exploitable gap between average farm yields and genetic yield potential
is closing. At present, the rate of increase in yield potential is much
less than the expected increase in demand. Hence, average farm yields
must reach 70–80% of the yield potential ceiling within 30 years in
each of these major cereal systems. Achieving consistent production at
these high levels without causing environmental damage requires
improvements in soil quality and precise management of all production
factors in time and space. The scope of the scientific challenge
related to these objectives is discussed. It is concluded that major
scientific breakthroughs must occur in basic plant physiology,
ecophysiology, agroecology, and soil science to achieve the ecological
intensification that is needed to meet the expected increase in food
demand.
MRP3, an organic anion transporter able to transport anti-cancer drugs
Authors: Kool Marcel , van der Linden Marcel , de Haas Marcel , Scheffer George L. , de Vree J. Marleen L. , Smith Alexander J. , Jansen Gerrit , Peters Godefridus J. , Ponne Nico , Scheper Rik J. , Elferink Ronald P. J. Oude , Baas Frank , Borst Piet
Published: July 2002

The human multidrug-resistance protein (
MRP
) gene family contains at least six members:
MRP1
, encoding the multidrug-resistance protein;
MRP2
or
cMOAT
, encoding the canalicular multispecific organic anion transporter; and four homologs, called
MRP3
,
MRP4
,
MRP5
, and
MRP6
. In this report, we characterize MRP3, the closest homolog of MRP1. Cell lines were retrovirally transduced with
MRP3
cDNA, and new monoclonal antibodies specific for MRP3 were generated. We show that MRP3 is an organic anion and multidrug transporter, like the GS-X pumps MRP1 and MRP2. In Madin–Darby canine kidney II cells, MRP3 routes to the basolateral membrane and mediates transport of the organic anion
S
-(2,4-dinitrophenyl-)glutathione toward the basolateral side of the monolayer. In ovarian carcinoma cells (2008), expression of
MRP3
results in low-level resistance to the epipodophyllotoxins etoposide and teniposide. In short-term drug exposure experiments, MRP3 also confers high-level resistance to methotrexate. Neither 2008 cells nor Madin–Darby canine kidney II cells overexpressing
MRP3
showed an increase in glutathione export or a decrease in the level of intracellular glutathione, in contrast to cells overexpressing
MRP1
or
MRP2
. We discuss the possible function of MRP3 in (hepatic) physiology and its potential contribution to drug resistance of cancer cells.
Optical recording of light-evoked calcium signals in the functionally intact retina
Authors: Denk Winfried , Detwiler Peter B.
Published: July 2002

Using two-photon excitation of fluorescent indicator dyes, we measured calcium concentration transients in retinal ganglion and amacrine cells without destroying the light sensitivity of the retina by maximally activating or bleaching the photoreceptors. This allowed an immediate assessment of the cellular morphology and study of the calcium signals evoked by visual stimuli. Calcium dynamics in individual dendritic processes could be examined for extensive periods without deterioration and with little apparent phototoxicity at excitation wavelengths of from 930 to 990 nm. Light-evoked increases in calcium were resolved in ganglion- and amacrine-cell neurites, making it possible to use optical recording to study the relationship between calcium signaling and retinal function.
Nephrin is specifically located at the slit diaphragm of glomerular podocytes
Authors: Ruotsalainen Vesa , Ljungberg Päivi , Wartiovaara Jorma , Lenkkeri Ulla , Kestilä Marjo , Jalanko Hannu , Holmberg Christer , Tryggvason Karl
Published: July 2002

We describe here the size and location of nephrin, the first protein to be identified at the glomerular podocyte slit diaphragm. In Western blots, nephrin antibodies generated against the two terminal extracellular Ig domains of recombinant human nephrin recognized a 180-kDa protein in lysates of human glomeruli and a 150-kDa protein in transfected COS-7 cell lysates. In immunofluorescence, antibodies to this transmembrane protein revealed reactivity in the glomerular basement membrane region, whereas the podocyte cell bodies remained negative. In immunogold-stained thin sections, nephrin label was found at the slit between podocyte foot processes. The congenital nephrotic syndrome of the Finnish type (NPHS1), a disease in which the nephrin gene is mutated, is characterized by massive proteinuria alreadyin uteroand lack of slit diaphragm and foot processes. These features, together with the now demonstrated localization of nephrin to the slit diaphragm area, suggests an essential role for this protein in the normal glomerular filtration barrier. A zipper-like model for nephrin assembly in the slit diaphragm is discussed, based on the present and previous data.
The evolution of language
Authors: Nowak Martin A. , Krakauer David C.
Published: July 2002

The emergence of language was a defining moment in the evolution of modern humans. It was an innovation that changed radically the character of human society. Here, we provide an approach to language evolution based on evolutionary game theory. We explore the ways in which protolanguages can evolve in a nonlinguistic society and how specific signals can become associated with specific objects. We assume that early in the evolution of language, errors in signaling and perception would be common. We model the probability of misunderstanding a signal and show that this limits the number of objects that can be described by a protolanguage. This “error limit” is not overcome by employing more sounds but by combining a small set of more easily distinguishable sounds into words. The process of “word formation” enables a language to encode an essentially unlimited number of objects. Next, we analyze how words can be combined into sentences and specify the conditions for the evolution of very simple grammatical rules. We argue that grammar originated as a simplified rule system that evolved by natural selection to reduce mistakes in communication. Our theory provides a systematic approach for thinking about the origin and evolution of human language.
Three-dimensional structure of low density lipoproteins by electron cryomicroscopy
Authors: Orlova Elena V. , Sherman Michael B. , Chiu Wah , Mowri Hiro , Smith Louis C. , Gotto Antonio M.
Published: July 2002

Human low density lipoproteins (LDL) are the major cholesterol carriers in the blood. Elevated concentration of LDL is a major risk factor for atherosclerotic disease. Purified LDL particles appear heterogeneous in images obtained with a 400-kV electron cryomicroscope. Using multivariate statistical and cluster analyses, an ensemble of randomly oriented particle images has been subdivided into homogeneous subpopulations, and the largest subset was used for three-dimensional reconstruction. In contrast to the general belief that below the lipid phase-transition temperature (30°C) LDL are quasi-spherical microemulsion particles with a radially layered core-shell organization, our three-dimensional map shows that LDL have a well-defined and stable organization. Particles consist of a higher-density outer shell and lower-density inner lamellae-like layers that divide the core into compartments. The outer shell consists of apolipoprotein B-100, phospholipids, and some free cholesterol.
Intravascular flow decreases erythrocyte consumption of nitric oxide
Authors: Liao James C. , W. Hein Travis , Vaughn Mark W. , Huang Kuang-Tse , Kuo Lih
Published: July 2002

Nitric oxide (NO) produced by the endothelium diffuses both into the lumen and to the smooth muscle cells according to the concentration gradient in each direction. The extremely high reaction rate between NO and hemoglobin (Hb),
k
Hb
= 3–5 × 10
7
M
−1
⋅s
−1
, suggests that most of the NO produced would be consumed by Hb in the red blood cells (RBCs), which then would block the biological effect of NO. Therefore, specific mechanisms must exist under physiological conditions to reduce the NO consumption by RBCs, in which the Hb concentration is very high (24 mM heme). By using isolated microvessels as a bioassay, here we show that physiological concentrations of RBCs in the presence of intravascular flow does not inhibit NO-mediated vessel dilation, suggesting that RBCs under this condition are not an NO scavenger. On the other hand, RBCs (50% hematocrit) without intravascular flow reduce NO-mediated dilation to serotonin by 30%. In contrast, free Hb (10 μM) completely inhibits NO-mediated dilation with or without intravascular flow. The effect of flow on NO consumption by RBCs may be attributed to the formation of an RBC-free zone near the vessel wall, which is caused by hydrodynamic forces on particles. Intravascular flow does not affect the reaction rate between NO and free Hb in the lumen, because the latter forms a homogeneous solution and is not subject to the hydrodynamic separation. However, intravascular flow only partially contributes to the reduced consumption of NO by RBCs, because without the flow, the NO consumption by RBCs is already about 3 orders of magnitude slower than free Hb.
Induction of apoptosis by adenovirus E4orf4 protein is specific to transformed cells and requires an interaction with protein phosphatase 2A
Authors: Shtrichman Ronit , Sharf Rakefet , Barr Haim , Dobner Thomas , Kleinberger Tamar
Published: July 2002

We previously have shown that adenovirus type 5 E4orf4 protein associates with protein phosphatase 2A (PP2A) and induces apoptosis in transformed cells in a p53-independent manner. Here we show that the interaction between E4orf4 and PP2A is required for induction of apoptosis by the viral protein. This conclusion is supported by a mutation analysis of E4orf4 protein, showing a correlation between the ability to bind PP2A and to induce apoptosis, and by the observation that transfection of an antisense construct of the PP2A-B55 subunit reduces expression of the PP2A-B55 subunit and inhibits induction of apoptosis by E4orf4, but not by p53. The mutant analysis also indicates that even a low level of interaction with PP2A is sufficient to initiate the E4orf4 apoptotic pathway. In addition, E4orf4 inhibits cellular transformation by various oncogenes, and this function is coupled to its ability to induce apoptosis. Furthermore, expression of oncogenes in primary cell cultures sensitizes these cells to induction of apoptosis by E4orf4. Our results suggest that E4orf4 is a potentially useful tool for cancer gene therapy.
Experimental demonstration that offspring sex ratio varies with maternal condition
Authors: Nager R. G. , Monaghan P. , Griffiths R. , Houston D. C. , Dawson R.
Published: July 2002

Sex ratio theory predicts that, if prevailing ecological or social circumstances differentially influence the fitness benefits of offspring of each sex, parents should adjust their production accordingly to maximize fitness. For species in which sex is chromosomally determined, such as birds and mammals, a differential effect of maternal condition on the fitness of male and female young is one important route whereby selection is expected to favor a bias in the offspring sex ratio at birth or egg laying. However, despite its central place in sex allocation theory, this hypothesis has rarely been tested in wild populations. We manipulated maternal condition upward and downward in a sexually dimorphic wild bird and examined the effect on offspring survival and on offspring sex ratio. The survival to fledging of male, but not female, young was substantially reduced if they came from less well provisioned eggs produced by females in relatively poor condition. As female condition, and thereby her capacity to produce high quality eggs, declined, she progressively skewed the sex ratio of her eggs toward females; i.e., she produced more of the sex with the higher survival prospects. The decline in the survival of male offspring, and the sex ratio bias, was removed when maternal condition was enhanced. These results provide experimental evidence of an adaptive, facultative adjustment of sex ratio in response to changes in maternal condition in wild birds.
Orexins, orexigenic hypothalamic peptides, interact with autonomic, neuroendocrine and neuroregulatory systems
Authors: Date Yukari , Ueta Yoichi , Yamashita Hiroshi , Yamaguchi Hideki , Matsukura Shigeru , Kangawa Kenji , Sakurai Takeshi , Yanagisawa Masashi , Nakazato Masamitsu
Published: July 2002

We determined the immunohistochemical distributions of orexin-A and orexin-B, hypothalamic peptides that function in the regulation of feeding behavior and energy homeostasis. Orexin-A and -B neurons were restricted to the lateral and posterior hypothalamus, whereas both orexin-A and -B nerve fibers projected widely into the olfactory bulb, cerebral cortex, thalamus, hypothalamus, and brainstem. Dense populations of orexin-containing fibers were present in the paraventricular thalamic nucleus, central gray, raphe nuclei, and locus coeruleus. Moderate numbers of these fibers were found in the olfactory bulb, insular, infralimbic and prelimbic cortex, amygdala, ventral, and dorsolateral parts of the suprachiasmatic nucleus, paraventricular nucleus except the lateral magnocellular division, arcuate nucleus, supramammillary nucleus, nucleus of the solitary tract, and dorsal motor nucleus of the vagus. Small numbers of orexin fibers were present in the perirhinal, motor and sensory cortex, hippocampus, and supraoptic nucleus, and a very small number in the lateral magnocellular division of the paraventricular nucleus. Intracerebroventricular injections of orexins induced c-
fos
expression in the paraventricular thalamic nucleus, locus coeruleus, arcuate nucleus, central gray, raphe nuclei, nucleus of the solitary tract, dorsal motor nucleus of the vagus, suprachiasmatic nucleus, supraoptic nucleus, and paraventricular nucleus except the lateral magnocellular division. The unique neuronal distribution of orexins and their functional activation of neural circuits suggest specific complex roles of the peptides in autonomic and neuroendocrine control.
Estrogen induction of the cyclin D1 promoter: Involvement of a cAMP response-like element
Authors: Sabbah Michele , Courilleau Delphine , Mester Jan , Redeuilh Gerard
Published: July 2002

Estrogens induce cell proliferation in target tissues by stimulating progression through the G
1
phase of the cell cycle. Induction of cyclin D1 expression is a critical feature of the mitogenic action of estrogen. We have determined a region between −96 and −29 in the cyclin D1 promoter that confers regulation by estrogens in the human mammary carcinoma cells MCF-7. This region encompasses a unique known transcription factor binding site with a sequence of a potential cAMP response element (CRE-D1). The induction is strictly hormone dependent and requires the DNA binding domain as well as both AF-1 and AF-2 domains of the estrogen receptor (ER) α. Destruction of the CRE-D1 motif caused complete loss of estrogen responsiveness. Both c-Jun and ATF-2 transactivated the cyclin D1 promoter in transient transfection experiments, and a clear additional increase was detected when ER was cotransfected with either c-Jun or with c-Jun and ATF-2 but not with ATF-2 alone. Furthermore, the expression of a dominant negative variant of c-Jun, TAM67, completely abolished the induction of the cyclin D1 promoter both in the absence and presence of ER. We show that ATF-2 homodimers and ATF-2/c-Jun heterodimers, but not c-Jun homodimers, were able to bind the CRE of the cyclin D1 promoter. To interpret these results, we propose a mechanism in which ATF-2/c-Jun heterodimers bind to the CRE-D1 element and mediate the activation of cyclin D1 promoter by the ER. This mechanism represents a pathway by which estrogens control the proliferation of target cells.
Presenilin 2 deficiency causes a mild pulmonary phenotype and no changes in amyloid precursor protein processing but enhances the embryonic lethal phenotype of presenilin 1 deficiency
Authors: Herreman An , Hartmann Dieter , Annaert Wim , Saftig Paul , Craessaerts Katleen , Serneels Lutgarde , Umans Lieve , Schrijvers Vincent , Checler Frédéric , Vanderstichele Hugo , Baekelandt Veerle , Dressel Ralf , Cupers Philippe , Huylebroeck Danny , Zwijsen An , Van Leuven Fred , De Strooper Bart
Published: July 2002

Mutations in the homologous presenilin 1 (PS1) and presenilin 2 (PS2) genes cause the most common and aggressive form of familial Alzheimer’s disease. Although PS1 function and dysfunction have been extensively studied, little is known about the function of PS2
in vivo
. To delineate the relationships of PS2 and PS1 activities and whether PS2 mutations involve gain or loss of function, we generated PS2 homozygous deficient (−/−) and PS1/PS2 double homozygous deficient mice. In contrast to PS1
−/−
mice, PS2
−/−
mice are viable and fertile and develop only mild pulmonary fibrosis and hemorrhage with age. Absence of PS2 does not detectably alter processing of amyloid precursor protein and has little or no effect on physiologically important apoptotic processes, indicating that Alzheimer’s disease-causing mutations in PS2, as in PS1, result in gain of function. Although PS1
+/−
PS2
−/−
mice survive in relatively good health, complete deletion of both PS2 and PS1 genes causes a phenotype closely resembling full Notch-1 deficiency. These results demonstrate
in vivo
that PS1 and PS2 have partially overlapping functions and that PS1 is essential and PS2 is redundant for normal Notch signaling during mammalian embryological development.
The inv(16) encodes an acute myeloid leukemia 1 transcriptional corepressor
Authors: Lutterbach Bart , Hou Yue , Durst Kristie L. , Hiebert Scott W.
Published: July 2002

The inv(16) is one of the most frequent chromosomal translocations associated with acute myeloid leukemia (AML). The inv(16) fusion protein acts by dominantly interfering with AML-1/core binding factor β-dependent transcriptional regulation. Here we demonstrate that the inv(16) fusion protein cooperates with AML-1B to repress transcription. This cooperativity requires the ability of the translocation fusion protein to bind to AML-1B. Mutational analysis and cell fractionation experiments indicated that the inv(16) fusion protein acts in the nucleus and that repression occurs when the complex is bound to DNA. We also found that the inv(16) fusion protein binds to AML-1B when it is associated with the mSin3A corepressor. An AML-1B mutant that fails to bind mSin3A was impaired in cooperative repression, suggesting that the inv(16) fusion protein acts through mSin3 and possibly other corepressors. Finally, we demonstrate that the C-terminal portion of the inv(16) fusion protein contains a repression domain, suggesting a molecular mechanism for AML-1-mediated repression.
Acquisition order and resource value inCuscuta attenuata
Authors: Kelly Colleen K. , Horning Kevin
Published: July 2002

Field observations showed that in its native Texas grasslands, dodder (Cuscuta attenuata) grows more vigorously in patches of mixed host species than in monospecific host patches. Field experiments with naturally occurring host individuals demonstrated that the parasite achieved greater volume when simultaneously infesting two hosts of differing species rather than two hosts of the same species, and that this effect depends on the order in which the parasite encounters those hosts. Sodium, acting as an osmoticum, is implicated as the factor responsible for experimentally produced as well as observed field patterns.
Models for stochastic climate prediction
Authors: Majda Andrew J. , Timofeyev Ilya , Vanden Eijnden Eric
Published: July 2002

There has been a recent burst of activity in the atmosphere/ocean sciences community in utilizing stable linear Langevin stochastic models for the unresolved degree of freedom in stochastic climate prediction. Here several idealized models for stochastic climate modeling are introduced and analyzed through unambiguous mathematical theory. This analysis demonstrates the potential need for more sophisticated models beyond stable linear Langevin equations. The new phenomena include the emergence of both unstable linear Langevin stochastic models for the climate mean and the need to incorporate both suitable nonlinear effects and multiplicative noise in stochastic models under appropriate circumstances. The strategy for stochastic climate modeling that emerges from this analysis is illustrated on an idealized example involving truncated barotropic flow on a beta-plane with topography and a mean flow. In this example, the effect of the original 57 degrees of freedom is well represented by a theoretically predicted stochastic model with only 3 degrees of freedom.
Glucose intolerance caused by a defect in the entero-insular axis: A study in gastric inhibitory polypeptide receptor knockout mice
Authors: Miyawaki Kazumasa , Yamada Yuichiro , Yano Hideki , Niwa Hitoshi , Ban Nobuhiro , Ihara Yu , Kubota Akira , Fujimoto Shinpei , Kajikawa Mariko , Kuroe Akira , Tsuda Kinsuke , Hashimoto Hiroyuki , Yamashita Tokuyuki , Jomori Takahito , Tashiro Fumi , Miyazaki Jun-ichi , Seino Yutaka
Published: July 2002

Mice with a targeted mutation of the gastric inhibitory polypeptide (GIP) receptor gene (
GIPR
) were generated to determine the role of GIP as a mediator of signals from the gut to pancreatic β cells.
GIPR
−/− mice have higher blood glucose levels with impaired initial insulin response after oral glucose load. Although blood glucose levels after meal ingestion are not increased by high-fat diet in
GIPR
+/+ mice because of compensatory higher insulin secretion, they are significantly increased in
GIPR
−/− mice because of the lack of such enhancement. Accordingly, early insulin secretion mediated by GIP determines glucose tolerance after oral glucose load
in vivo
, and because GIP plays an important role in the compensatory enhancement of insulin secretion produced by a high insulin demand, a defect in this entero-insular axis may contribute to the pathogenesis of diabetes.
A subset of skin tumor modifier loci determines survival time of tumor-bearing mice
Authors: Nagase Hiroki , Mao Jian-Hua , Balmain Allan
Published: July 2002

Studies of mouse models of human cancer have established the existence of multiple tumor modifiers that influence parameters of cancer susceptibility such as tumor multiplicity, tumor size, or the probability of malignant progression. We have carried out an analysis of skin tumor susceptibility in interspecificMus musculus/Mus spretushybrid mice and have identified another seven loci showing either significant (six loci) or suggestive (one locus) linkage to tumor susceptibility or resistance. A specific search was carried out for skin tumor modifier loci associated with time of survival after development of a malignant tumor. A combination of resistance alleles at three markers [D6Mit15(Skts12),D7Mit12(Skts2), andD17Mit7(Skts10)], all of which are close to or the same as loci associated with carcinoma incidence and/or papilloma multiplicity, is significantly associated with increased survival of mice with carcinomas, whereas the reverse combination of susceptibility alleles is significantly linked to early mortality caused by rapid carcinoma growth (χ2= 25.22;P= 5.1 × 10−8). These data indicate that host genetic factors may be used to predict carcinoma growth rate and/or survival of individual backcross mice exposed to the same carcinogenic stimulus and suggest that mouse models may provide an approach to the identification of genetic modifiers of cancer survival in humans.
Apolipoprotein E is essential for amyloid deposition in theAPPV717Ftransgenic mouse model of Alzheimer's disease
Authors: Bales Kelly R. , Verina Tatyana , Cummins David J. , Du Yansheng , Dodel Richard C. , Saura Josep , Fishman Cindy E. , DeLong Cynthia A. , Piccardo Pedro , Petegnief Valerie , Ghetti Bernardino , Paul Steven M.
Published: July 2002

We quantified the amount of amyloid β-peptide (Aβ) immunoreactivity as well as amyloid deposits in a large cohort of transgenic mice overexpressing the V717F human amyloid precursor protein (APPV717F+/−TG mice) with no, one, or two mouse apolipoprotein E (Apoe) alleles at various ages. Remarkably, no amyloid deposits were found in any brain region ofAPPV717F+/−Apoe−/−TG mice as old as 22 mo of age, whereas age-matchedAPPV717F +/−Apoe+/−andApoe+/+TG mice display abundant amyloid deposition. The amount of Aβ immunoreactivity in the hippocampus was also markedly reduced in anApoegene dose-dependent manner (Apoe+/+>Apoe+/−≫Apoe−/−), and no Aβ immunoreactivity was detected in the cerebral cortex ofAPPV717F+/−Apoe−/−TG mice at any of the time points examined. The absence of apolipoprotein E protein (apoE) dramatically reduced the amount of both Aβ1–40and Aβ1–42immunoreactive deposits as well as the resulting astrogliosis and microgliosis normally observed inAPPV717FTG mice. ApoE immunoreactivity was detected in a subset of Aβ immunoreactive deposits and in virtually all thioflavine-S-fluorescent amyloid deposits. Because the absence of apoE alters neither the transcription or translation of theAPPV717Ftransgene nor its processing to Aβ peptide(s), we postulate that apoE promotes both the deposition and fibrillization of Aβ, ultimately affecting clearance of protease-resistant Aβ/apoE aggregates. ApoE appears to play an essential role in amyloid deposition in brain, one of the neuropathological hallmarks of Alzheimer's disease.
Role of mitochondrial lactate dehydrogenase and lactate oxidation in the intracellular lactate shuttle
Authors: Brooks George A. , Dubouchaud Hervé , Brown Marcia , Sicurello James P. , Butz C. Eric
Published: July 2002

To evaluate the potential role of mitochondrial lactate dehydrogenase (LDH) in tissue lactate clearance and oxidation
in vivo
,
isolated rat liver, cardiac, and skeletal muscle mitochondria were incubated with lactate, pyruvate, glutamate, and succinate. As well, α-cyano-4-hydroxycinnamate (CINN), a known monocarboxylate transport inhibitor, and oxamate, a known LDH inhibitor were used. Mitochondria readily oxidized pyruvate and lactate, with similar state 3 and 4 respiratory rates, respiratory control (state 3/state 4), and ADP/O ratios. With lactate or pyruvate as substrates, α-cyano-4-hydroxycinnamate blocked the respiratory response to added ADP, but the block was bypassed by addition of glutamate (complex I-linked) and succinate (complex II-linked) substrates. Oxamate increased pyruvate (≈10–40%), but blocked lactate oxidation. Gel electrophoresis and electron microscopy indicated LDH isoenzyme distribution patterns to display tissue specificity, but the LDH isoenzyme patterns in isolated mitochondria were distinct from those in surrounding cell compartments. In heart, LDH-1 (H4) was concentrated in mitochondria whereas LDH-5 (M4) was present in both mitochondria and surrounding cytosol and organelles. LDH-5 predominated in liver but was more abundant in mitochondria than elsewhere. Because lactate exceeds cytosolic pyruvate concentration by an order of magnitude, we conclude that lactate is the predominant monocarboxylate oxidized by mitochondria
in vivo
. Mammalian liver and striated muscle mitochondria can oxidize exogenous lactate because of an internal LDH pool that facilitates lactate oxidation.
Differential regulation of maternal vs. paternal centrosomes
Authors: Wu Xingyong , Palazzo Robert E.
Published: July 2002

Centrosomes are the main microtubule-organizing centers in animal
cells. During meiosis and mitosis, two centrosomes form the poles that
direct the assembly of a bipolar spindle, thus ensuring the accurate
segregation of chromosomes. Cells cannot tolerate the presence of more
than two active centrosomes during meiosis or mitosis because doing so
results in the formation of multipolar spindles, infidelity in
chromosome segregation, and aneuploidy. Here, we show that
fertilization of
Spisula solidissima
oocytes results in
cells that contain three active centrosomes, two maternal and one
paternal. During meiosis I, the paternal centrosome’s ability to
nucleate microtubules is selectively shut off while maternal
centrosomes remain competent to nucleate microtubules and assemble
asters in the same cytoplasm. We propose that embryos can identify
paternal vs. maternal centrosomes and can control them differentially.
Activating and dominant inactivating c-KITcatalytic domain mutations in distinct clinical forms of human mastocytosis
Authors: Longley B. Jack , Metcalfe Dean D. , Tharp Michael , Wang Xiaomei , Tyrrell Lynda , Lu Shu-zhuang , Heitjan David , Ma Yongsheng
Published: July 2002

Human mastocytosis is characterized by increased mast cells. It usually occurs as a sporadic disease that is often transient and limited in children and persistent or progressive in adults. The c-KITprotooncogene encodes KIT, a tyrosine kinase that is the receptor for mast cell growth factor. Because mutated KIT can transform cells, we examined c-KITin skin lesions of 22 patients with sporadic mastocytosis and 3 patients with familial mastocytosis. All patients with adult sporadic mastocytosis had somatic c-KITmutations in codon 816 causing substitution of valine for aspartate and spontaneous activation of mast cell growth factor receptor (P= 0.0001). A subset of four pediatric onset cases with clinically unusual disease also had codon 816 activating mutations substituting valine, tyrosine, or phenylalanine for aspartate. Typical pediatric patients lacked 816 mutations, but limited sequencing showed three of six had a novel dominant inactivating mutation substituting lysine for glutamic acid in position 839, the site of a potential salt bridge that is highly conserved in receptor tyrosine kinases. No c-KITmutations were found in the entire coding region of three patients with familial mastocytosis. We conclude that c-KITsomatic mutations substituting valine in position 816 of KIT are characteristic of sporadic adult mastocytosis and may cause this disease. Similar mutations causing activation of the mast cell growth factor receptor are found in children apparently at risk for extensive or persistent disease. In contrast, typical pediatric mastocytosis patients lack these mutations and may express inactivating c-KITmutations. Familial mastocytosis, however, may occur in the absence of c-KITcoding mutations.
Abnormalities at 14q32.1 in T cell malignancies involve two oncogenes
Authors: Pekarsky Yuri , Hallas Cora , Isobe Masaharu , Russo Giandomenico , Croce Carlo M.
Published: July 2002

The
TCL1
oncogene on human chromosome 14q32.1 is involved in the development of T cell leukemia in humans. Its expression in these leukemias is activated by chromosomal translocations and inversions at 14q32.1. Here we report the isolation and characterization of a new member of the
TCL1
gene family,
TCL1b,
located ≈16 kb centromeric of
TCL1
. The 1.2-kb
TCL1b
cDNA encodes a 14-kDa protein of 128 aa and shows 60% similarity to Tcl1. Expression profiles of
TCL1
and
TCL1b
genes are very similar: both genes are expressed at very low levels in normal bone marrow and peripheral lymphocytes but are activated in T cell leukemia by rearrangements of the 14q32.1 region. Thus, translocations and inversions at 14q32.1 in T cell malignancies involve two oncogenes.