bluuebunny/crossref_metadata_2025 huggingface dataset:
Prefrontal cortex and hippocampus subserve different components of working memory in rats
Authors: Yoon Taejib , Okada Jeffrey , Jung Min W. , Kim Jeansok J.
Published: February 2008

Both the medial prefrontal cortex (mPFC) and hippocampus are implicated in working memory tasks in rodents. Specifically, it has been hypothesized that the mPFC is primarily engaged in the temporary storage and processing of information lasting from a subsecond to several seconds, while the hippocampal function becomes more critical as the working memory demand extends into longer temporal scales. Although these structures may be engaged in a temporally separable manner, the extent of their contributions in the “informational content” of working memory remains unclear. To investigate this issue, the mPFC and dorsal hippocampus (dHPC) were temporarily inactivated via targeted infusions of the GABAA receptor agonist muscimol in rats prior to their performance on a delayed alternation task (DAT), employing an automated figure-eight maze that required the animals to make alternating arm choice responses after 3-, 30-, and 60-sec delays for water reward. We report that inactivation of either the mPFC or dHPC significantly reduced DAT at all delay intervals tested. However, there were key qualitative differences in the behavioral effects. Specifically, mPFC inactivation selectively impaired working memory (i.e., arm choice accuracy) without altering reference memory (i.e., the maze task rule) and arm choice response latencies. In contrast, dHPC inactivation increased both reference memory errors and arm choice response latencies. Moreover, dHPC, but not mPFC, inactivation increased the incidence of successive working memory errors. These results suggest that while both the mPFC and hippocampus are necessarily involved in DAT, they seem to process different informational components associated with the memory task.
Transcriptional and Metabolic Adjustments in ADP-Glucose Pyrophosphorylase-Deficientbt2Maize Kernels
Authors: Cossegal Magalie , Chambrier Pierre , Mbelo Sylvie , Balzergue Sandrine , Martin-Magniette Marie-Laure , Moing Annick , Deborde Catherine , Guyon Virginie , Perez Pascual , Rogowsky Peter
Published: February 2008

During the cloning of monogenic recessive mutations responsible for a defective kernel phenotype in a Mutator-induced Zea mays mutant collection, we isolated a new mutant allele in Brittle2 (Bt2), which codes for the small subunit of ADP-glucose pyrophosphorylase (AGPase), a key enzyme in starch synthesis. Reverse transcription-polymerase chain reaction experiments with gene-specific primers confirmed a predominant expression of Bt2 in endosperm, of Agpsemzm in embryo, and of Agpslzm in leaf, but also revealed considerable additional expression in various tissues for all three genes. Bt2a, the classical transcript coding for a cytoplasmic isoform, was almost exclusively expressed in the developing endosperm, whereas Bt2b, an alternative transcript coding for a plastidial isoform, was expressed in almost all tissues tested with a pattern very similar to that of Agpslzm. The phenotypic analysis showed that, at 30 d after pollination (DAP), mutant kernels were plumper than wild-type kernels, that the onset of kernel collapse took place between 31 and 35 DAP, and that the number of starch grains was greatly reduced in the mutant endosperm but not the mutant embryo. A comparative transcriptome analysis of wild-type and bt2-H2328 kernels at middevelopment (35 DAP) with the 18K GeneChip Maize Genome Array led to the conclusion that the lack of Bt2-encoded AGPase triggers large-scale changes on the transcriptional level that concern mainly genes involved in carbohydrate or amino acid metabolic pathways. Principal component analysis of 1H nuclear magnetic resonance metabolic profiles confirmed the impact of the bt2-H2328 mutation on these pathways and revealed that the bt2-H2328 mutation did not only affect the endosperm, but also the embryo at the metabolic level. These data suggest that, in the bt2-H2328 endosperms, regulatory networks are activated that redirect excess carbon into alternative biosynthetic pathways (amino acid synthesis) or into other tissues (embryo).
The structure of the lipid‐embedded potassium channel voltage sensor determined by double‐electron–electron resonance spectroscopy
Authors: Vamvouka Magdalini , Cieslak John , Van Eps Ned , Hubbell Wayne , Gross Adrian
Published: February 2008

A four‐pulse electron paramagnetic resonance experiment was used to measure long‐range inter‐subunit distances in reconstituted KvAP, a voltage‐dependent potassium (Kv) channel. The measurements have allowed us to reach the following five conclusions about the native structure of the voltage sensor of KvAP. First, the S1 helix of the voltage sensor engages in a helix packing interaction with the pore domain. Second, the crystallographically observed antiparallel helix‐turn‐helix motif of the voltage‐sensing paddle is retained in the membrane‐embedded voltage sensor. Third, the paddle is oriented in such a way as to expose one face to the pore domain and the opposite face to the membrane. Fourth, the paddle and the pore domain appear to be separated by a gap that is sufficiently wide for lipids to penetrate between the two domains. Fifth, the critical voltage‐sensing arginine residues on the paddle appear to be lipid exposed. These results demonstrate the importance of the membrane for the native structure of Kv channels, suggest that lipids are an integral part of their native structure, and place the voltage‐sensing machinery into a complex lipid environment near the pore domain.
Structural constraints on autoprocessing of the human nucleoporin Nup98
Authors: Sun Yixin , Guo Hwai‐Chen
Published: February 2008

Nucleoporin Nup98, a 98‐kDa protein component of the nuclear pore complex, plays an important role in both protein and RNA transport. During its maturation process, Nup98 undergoes post‐translational autoproteolysis, which is critical for targeting to the NPC. Here we present high‐resolution crystal structures of the C‐terminal autoproteolytic domains of Nup98 (2.3 Å for the wild type and 1.9 Å for the S864A precursor), and propose a detailed autoproteolysis mechanism through an N–O acyl shift. Structural constraints are found at the autocleavage site, and could thus provide a driving force for autocleavage at the scissile peptide bond. Such structural constraints appear to be generated, at least in part, by anchoring a conserved phenylalanine side chain into a highly conserved hydrophobic pocket at the catalytic site. Our high‐resolution crystal structures also reveal that three highly conserved residues, Tyr866, Gly867, and Leu868, provide most of the interactions between the autoproteolytic domain and the C‐terminal tail. These results suggest that Nup98 may represent a new subtype of protein that utilizes autoprocessing to control biogenesis pathways and intracellular translocation.
Crystal structure of LpxC from Pseudomonas aeruginosa complexed with the potent BB‐78485 inhibitor
Authors: Mochalkin Igor , Knafels John D. , Lightle Sandra
Published: February 2008

The cell wall in Gram‐negative bacteria is surrounded by an outer membrane comprised of charged lipopolysaccharide (LPS) molecules that prevent entry of hydrophobic agents into the cell and protect the bacterium from many antibiotics. The hydrophobic anchor of LPS is lipid A, the biosynthesis of which is essential for bacterial growth and viability. UDP‐3‐O‐(R‐3‐hydroxymyristoyl)‐N‐acetylglucosamine deacetylase (LpxC) is an essential zinc‐dependant enzyme that catalyzes the conversion of UDP‐3‐O‐(R‐3‐hydroxymyristoyl)‐N‐acetylglucosamine to UDP‐3‐O‐(R‐3‐hydroxymyristoyl)glucosamine and acetate in the biosynthesis of lipid A, and for this reason, LpxC is an attractive target for antibacterial drug discovery. Here we disclose a 1.9 Å resolution crystal structure of LpxC from Pseudomonas aeruginosa (paLpxC) in a complex with the potent BB‐78485 inhibitor. To our knowledge, this is the first crystal structure of LpxC with a small‐molecule inhibitor that shows antibacterial activity against a wide range of Gram‐negative pathogens. Accordingly, this structure can provide important information for lead optimization and rational design of the effective small‐molecule LpxC inhibitors for successful treatment of Gram‐negative infections.
Ontogenetic allometries and shape changes in the suckermouth armoured catfish Ancistruscf.triradiatus Eigenmann (Loricariidae, Siluriformes), related to suckermouth attachment and yolk‐sac size
Authors: Geerinckx T. , Verhaegen Y. , Adriaens D.
Published: February 2008

Early life‐history stages of the loricariid catfish Ancistruscf.triradiatus are described, from pre‐hatch embryos to juveniles. The descriptions, as well as metric characters, indicate that the free‐swimming embryonic stage is followed directly by the juvenile stage, without a true larval stage or metamorphosis. Intense, but gradual ontogenetic head‐shape changes are present during the embryonic and free‐living embryonic stages: the suckermouth gradually shifts from an almost rostral to a ventral position. The external and internal transformations related to this shape change are considered an adaptation to both the loricariid algae‐scraping feeding mode and the need of suckermouth functioning from the moment of hatching, when a ventrally situated suckermouth would be disadvantageous, as a large yolk sac is present.
Seasonal prevalence and intensity of follicular atresia in Baltic cod Gadus morhua callarias L.
Authors: Kraus G. , Tomkiewicz J. , Diekmann R. , Köster F. W.
Published: February 2008

In the present study, 307 ovaries of eastern Baltic cod Gadus morhua callarias sampled during the prespawning and spawning season 2000 were analysed histologically to estimate the seasonal prevalence and intensity of atresia. The number of atretic oocytes per ovary was estimated using a combination of the physical disector method and volume fraction (Delesse principle). Atretic oocytes were observed in 32% of the ovaries. Prevalence of atresia was independent of female size, but increased significantly with declining female condition from prespawning and through the spawning stages. The relative intensity of atresia, i.e. number of atretic oocytes in relation to normally developed vitellogenic oocytes, was low amounting to 1·4% on average. Similar to prevalence, relative intensity of atresia differed significantly between maturity stages and increased with decreasing female condition. The population egg loss due to atresia amounted to 4·6% indicating that Baltic cod was performing close to maximum productivity, i.e. potential egg production.
The visual pigments of a deep‐sea myctophid fish Myctophum nitidulum Garman; an HPLC and spectroscopic description of a non‐paired rhodopsin–porphyropsin system
Authors: Hasegawa E. I. , Sawada K. , Abe K. , Watanabe K. , Uchikawa K. , Okazaki Y. , Toyama M. , Douglas R. H.
Published: February 2008

Unusually for a deep‐sea fish, the retina of the myctophid (lanternfish) Myctophum nitidulum was found to contain two visual pigments, shown by extract spectrophotometry to be maximally sensitive at 468 and 522 nm, respectively, giving this species one of the broadest spectral ranges of all deep‐sea fishes. High performance liquid chromatography (HPLC) indicated that the retina contained both A1‐ and A2‐based chromophores. Surprisingly, the maximum absorbance (λmax) values of the two visual pigments were too far apart to form a rhodopsin–porphyropsin ‘pigment pair’, suggesting they were based on distinct opsins each linked to a different chromophore. This might be an adaptation to the detection of both long‐wave bioluminescence and residual shorter‐wave surface illumination, and could be related to this animal’s tendency to migrate towards surface waters at night.
Relationship between scale growth checks, circuli formation rate and somatic growth in Rutilus rutilus (L.) a fish farm‐reared cyprinid
Authors: Ibáñez A. L. , Britton J. R. , Cowx I. G.
Published: February 2008

Check formation on scales of roach Rutilus rutilus was examined during their production cycle at a fish farm in England through analysis of circuli patterns. Regular check formation was associated with the movement of fish from one type of grow‐out facility to another; this resulted in a sudden shift in growth rate and the formation of a new check. As these had the characteristics of annual marks, their formation potentially invalidates their use as structures to determine the age of individuals during recapture events that may follow their introduction to the wild. At low growth rates, the number of circuli was constant throughout the year; this situation changed when fast growth rates were achieved. Five methods of backcalculation were also validated. When the proportionality between the body length and scale radii was weak, backcalculation methods were poor in determining length at check formation.
Tumor‐derived tumor necrosis factor‐alpha promotes progression and epithelial‐mesenchymal transition in renal cell carcinoma cells
Authors: Chuang Mei‐Jen , Sun Kuang‐Hui , Tang Shye‐Jye , Deng Ming‐Wei , Wu Yu‐Hsin , Sung Jung‐Sung , Cha Tai‐Lung , Sun Guang‐Huan
Published: February 2008

Pro‐inflammatory cytokines and chemokines are involved in promoting tumorigenesis by facilitating tumor proliferation and metastasis. The serum levels of interleukin (IL)‐6, IL‐1β, and tumor necrosis factor‐alpha (TNF‐α) are significantly elevated in patients with renal cell carcinoma (RCC). However, the mechanisms of how these cytokines participate in the progression of RCC remains unknown. In the present study, we investigated the effects of tumor‐derived cytokines on invasion and the epithelial‐mesenchymal transition (EMT) of RCC cells. We found that expression of IL‐1β, IL‐6, TNF‐α, hypoxia‐inducible factor‐alpha (HIF‐1α), and matrix metalloproteinase‐2 (MMP2) were significantly elevated in high malignancy A498 cells compared to low malignancy 786‐O cells. The invasion ability of A498 was three‐fold higher than that of 786‐O cells. The invasiveness of 786‐O cells was markedly enhanced by adding conditioned medium derived from A498 cells. This phenomenon was significantly inhibited by immunodepletion of TNF‐α followed by MMP2, IL‐6, or IL‐1β from A498 conditioned medium. Synergistic inhibition was also noted after simultaneous immunodepletion of TNF‐α, IL‐1β, and IL‐6. RCC cell lines with higher malignancy produced more TNF‐α, which was correlated with their stronger invasive ability. The invasiveness of 786‐O cells was significantly promoted by TNF‐α in a dose‐dependent manner. Moreover, TNF‐α induced the EMT of 786‐O cells by repressing E‐cadherin, promoting vimentin expression, and activating MMP9 activity. Our findings demonstrate that pro‐inflammatory cytokines, especially TNF‐α, can enhance invasion and the EMT of renal cancer cells, which provides a therapeutic target to prevent and treat advanced RCC. (Cancer Sci 2008; 99: 905–913)
Use of a sparse sampling study design to assess transfer of tramadol and its O‐desmethyl metabolite into transitional breast milk
Authors: Ilett Kenneth F. , Paech Michael J. , Page‐Sharp Madhu , Sy Sherwin K. , Kristensen Judith H. , Goy Raymond , Chua Sebastian , Christmas Tracey , Scott Karen L.
Published: February 2008

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

• There are presently no published data on tramadol transfer into breast milk or on its effects in the breastfed infant.

WHAT THIS STUDY ADDS

• We have provided quantitative data on the absolute and relative infant doses of rac‐tramadol and it rac‐O‐desmethyl metabolite for the breastfed infant.

• We have also demonstrated a novel sparse sampling data collection method for investigating infant exposure via milk.

AIMS

To investigate the transfer of rac‐tramadol and its rac‐O‐desmethyl metabolite into transitional milk, and assess unwanted effects in the breastfed infant.

METHODS

Tramadol HCl (100 mg six hourly) was administered to 75 breastfeeding mothers for postoperative analgesia on days 2–4 after Caesarian section. Milk and plasma samples were collected after administration of four or more doses. Rac‐tramadol and rac‐O‐desmethyltramadol were measured by high performance liquid chromatography. Milk : plasma ratio (M : P) and infant doses were calculated by standard methods. The behavioural characteristics of the exposed breastfed infants and a matched control group of infants not exposed to tramadol were also studied.

RESULTS

At steady‐state, mean (95% CI) M : P was 2.2 (2.0, 2.4) for rac‐tramadol and 2.8 (2.5, 3.1) for rac‐O‐desmethyltramadol. The estimated absolute and relative infant doses were 112 (102, 122) μg kg−1 day−1 and 30 (28, 32) μg kg−1 day−1, and 2.24% (2.04, 2.44)% and 0.64% (0.59, 0.69)% for rac‐tramadol and rac‐O‐desmethyltramadol, respectively. The exposed infants and control breastfed infants had similar characteristics, including Apgar scores at birth and Neurologic and Adaptive Capacity Scores.

CONCLUSIONS

The combined relative infant dose of 2.88% at steady‐state was low. The similarity of NACS in exposed infants and controls suggests that there were no significant behavioural adverse effects. We conclude that short‐term maternal use of tramadol during establishment of lactation is compatible with breastfeeding.
Fludarabine‐based cytoreductive regimen and T‐cell‐depleted grafts from alternative donors for the treatment of high‐risk patients with Fanconi anaemia
Authors: Chaudhury Sonali , Auerbach Arleen D. , Kernan Nancy A. , Small Trudy N. , Prockop Susan E. , Scaradavou Andromachi , Heller Glenn , Wolden Suzanne , O’Reilly Richard J. , Boulad Farid
Published: February 2008

Eighteen consecutive patients aged 5·5–24 years with Fanconi anaemia and diagnoses of aplastic anaemia (n = 8), myelodysplastic syndrome (n = 4), acute myeloid leukaemia (n = 6), received allogeneic haematopoietic stem cell transplants from alternative donors. All patients had been transfused, 13 had previously been treated with androgens and 14 had a history of infection. Donors were related human leucocyte antigen (HLA) mismatched for eight patients, unrelated HLA mismatched for seven patients and unrelated HLA matched for three patients. Cytoreduction included single dose total body irradiation (450 cGy), fludarabine (150 mg/m2) and cyclophosphamide (40 mg/kg). Immunosuppression included antithymocyte globulin and tacrolimus. Grafts were granulocyte colony‐stimulating factor‐mobilized, CD34+ T‐cell‐depleted peripheral blood stem cells in 15 patients and T‐cell‐depleted marrows in three. All 18 patients engrafted with 100% donor chimaerism; only one patient developed graft‐versus‐host disease (GVHD). With a median follow‐up of 4·2 years, 13/18 patients were alive, 12 of these were disease‐free. Five‐year overall survival and disease‐free survival were 72·2% and 66·6% respectively. Immune reconstitution was achieved at approximately 6 months post‐transplant for most patients. These are encouraging results of T‐cell‐depleted transplants from alternative donors using fludarabine‐based cytoreduction in 18 high‐risk patients with Fanconi anaemia, with no evidence of rejection and minimal GVHD.
Alcohol consumption and the risk of self‐reported perennial and seasonal allergic rhinitis in young adult women in a population‐based cohort study
Authors: Bendtsen P. , Grønbæk M. , Kjær S. K. , Munk C. , Linneberg A. , Tolstrup J. S.
Published: February 2008

BackgroundAlcohol consumption has been suggested to be associated with the development of allergic rhinitis (AR), but there is limited data on the topic.

ObjectivesThe objective of this study was to investigate the association between alcohol consumption and the risk of developing AR among young women.

MethodsFive thousand eight hundred and seventy Danish women aged 20–29 years participated in a prospective cohort study, and were free of seasonal and perennial AR at baseline (1991–1993). Alcohol consumption was assessed by a food frequency questionnaire. The main outcome measures were self‐reported information on seasonal and perennial AR debuting during a mean follow‐up period of 7.8 years.

ResultsDuring follow‐up, 831 women developed seasonal AR and 523 women developed perennial AR, corresponding to 14% and 9%. Alcohol consumption was positively associated with the risk of developing perennial AR. The adjusted odds ratio (OR) for perennial AR was 1.78 (95% CI, 1.13–2.80) among women drinking more than 14 drinks/week compared with women drinking <1 drink/week. There was no association between alcohol consumption and seasonal AR. Having one or two parents with asthma was, after adjustment, significantly associated with the risk of developing seasonal (OR, 2.01; 95% CI, 1.65–2.45) and perennial AR (OR, 2.28; 95% CI, 1.70–2.74). Smoking was not associated with an increased risk of developing AR.

ConclusionIn this population of young adult women, alcohol consumption was associated with an increased risk of developing perennial AR.
Effect of ripeness at processing on fresh‐cut ‘Flor de Invierno’ pears packaged under modified atmosphere conditions
Authors: Oms‐Oliu Gemma , Aguiló‐Aguayo Ingrid , Soliva‐Fortuny Robert , Martín‐Belloso Olga
Published: February 2008

The effects of ripeness at processing and packaging conditions on respiration, microbiological stability as well as colour and firmness of fresh‐cut ‘Flor de Invierno’ pears were evaluated throughout storage. Although a 2.5‐kPa O2 + 7‐kPa CO2 atmosphere led to an inhibition of ethylene synthesis and carbon dioxide production compared with non‐modified atmosphere packaging, the more advanced the ripeness stage at processing, the higher the physiological activity and thus, the higher production of carbon dioxide, ethylene and ethanol. A 2.5‐kPa O2 + 7‐kPa CO2 atmosphere inhibited bacterial growth, yeast and mould proliferation in mature‐green pears but fast microbial growth was observed especially on ripe pears, under both packaging conditions. In conclusion, the shelf‐life of ripe pears was reduced by increased respiration response to processing and accelerated microbial spoilage. Instead, pears processed in a partially ripe stage were suitable for conservation while gathering desired sensory attributes. Therefore, for commercial purposes, a shelf‐life of 10 days was suggested for partially ripe fresh‐cut pears packaged under a 2.5‐kPa O2 + 7‐kPa CO2 atmosphere.
Caustic‐induced gelation of β‐lactoglobulin
Authors: Mercadé‐Prieto Ruben , Paterson William R. , Ian Wilson D.
Published: February 2008

The gelation kinetics of β‐lactoglobulin (βLg) solutions has been determined in the alkaline regime over a wide range of protein concentrations, gelling temperatures and gelation pH (pHgel), set using NaOH. The behaviour is compared with caustic‐induced gelation of whey protein concentrate and the alkaline dissolution of heat‐induced whey gels. The gelation time decreases significantly between neutral conditions and pHgel 9, because of the activation of the free cysteine groups and displacement to the monomeric form, and between pHgel 10 and 11, due to the base denaturation of βLg. Both transitions are associated with a significant decrease in the activation energy of gelation. At pHgel >11.5 the gelation time is observed to increase with pHgel, owing to destruction of interprotein crosslinks. These results are consistent with the recently reported observation that a minimum pH for the dissolution of βLg gels and aggregates exists around 11.6 [Biomacromolecules8 (2007) 1162]. This phenomenon has been assigned to the destruction of non‐covalent interactions that would inhibit the final percolation of the gel.
The metabolic syndrome as a tool for predicting future diabetes: the AusDiab study
Authors: Cameron A. J. , Magliano D. J. , Zimmet P. Z. , Welborn T. A. , Colagiuri S. , Tonkin A. M. , Shaw J. E.
Published: February 2008

Objective.  To compare the ability of the metabolic syndrome (MetS), a diabetes prediction model (DPM), a noninvasive risk questionnaire and individual glucose measurements to predict future diabetes.

Design.  Five‐year longitudinal cohort study. Tools tested included MetS definitions [World Health Organization, International Diabetes Federation, ATPIII and European Group for the study of Insulin Resistance (EGIR)], the FINnish Diabetes RIsk SCore risk questionnaire, the DPM, fasting and 2‐h post load plasma glucose.

Setting.  Adult Australian population.

Subjects.  A total of 5842 men and women without diabetes ≥25 years. Response 58%. A total of 224 incident cases of diabetes.

Results.  In receiver operating characteristic curve analysis, the MetS was not a better predictor of incident diabetes than the DPM or measurement of glucose. The risk for diabetes among those with prediabetes but not MetS was almost triple that of those with MetS but not prediabetes (9.0% vs. 3.4%). Adjusted for component parts, the MetS was not a significant predictor of incident diabetes, except for EGIR in men [OR 2.1 (95% CI 1.2–3.7)].

Conclusions.  A single fasting glucose measurement may be more effective and efficient than published definitions of the MetS or other risk constructs in predicting incident diabetes. Diagnosis of the MetS did not confer increased risk for incident diabetes independent of its individual components, with an exception for EGIR in men. Given these results, debate surrounding the public health utility of a MetS diagnosis, at least for identification of incident diabetes, is required.
Ghrelin Stimulates Milk Intake by Affecting Adult Type Feeding Behaviour in Postnatal Rats
Authors: Piao H. , Hosoda H. , Kangawa K. , Murata T. , Narita K. , Higuchi T.
Published: February 2008

The influence of ghrelin on feeding behaviour during infancy is unknown. To determine whether ghrelin influences milk intake in rat pups, newborn rats received a single i.p. injection of either rat ghrelin (100 μg/kg) or rabbit anti‐ghrelin immunoglobulin G (100 μg/kg) every 5 days from postpartum day 5 to day 30 (P5–P30). Milk intake was then assessed by body weight gain following a 2‐h suckling period. Ghrelin significantly increased weight gain relative to vehicle‐injected controls in P20, P25 and P30 pups, but not in younger animals. Similarly, after 8 h of milk restriction, anti‐ghrelin injections significantly decreased weight gain in P25 and P30, but not in younger pups. Interestingly, however, ghrelin did increase independent feeding in P10 and P15 pups using a paradigm in which pups consumed milk from a milk‐soaked paper towel. We therefore conclude that ghrelin stimulates milk intake at an early postnatal stage, primarily by affecting adult‐type feeding behaviour.
The Selective Oestrogen Receptor Modulator, LY362321, is Not Neuroprotective in a Rat Model of Transient Focal Ischaemia
Authors: Farr T. D. , Carswell H. V. O. , McCann D. J. , Sato M. , Bryant H. U. , Dodge J. A. , Macrae I. M.
Published: February 2008

Selective oestrogen receptor modulators (SERMs) may offer improved alternatives to oestrogen as neuroprotectants in experimental stroke. The present study investigated the role of a novel SERM, LY362321, in a rat model of transient middle cerebral artery occlusion (MCAO). Female Sprague‐Dawley rats were ovariectomised and began receiving daily s.c. injections of either 1 mg/kg (n = 13), 10 mg/kg (n = 14) of LY362321, or vehicle (n = 13). The left MCA was temporarily occluded (90 min), with cortical blood flow monitoring, at 12 days post ovariectomy. Sensorimotor function was assessed using a neurological score prior to the MCAO and daily for 3 days following the MCAO. Tissue was processed for infarct volume assessment using 2,3,5‐triphenyltetra‐zolium chloride staining. The results indicated that there were no significant differences amongst groups in cortical blood flow during the MCAO. Furthermore, there was no significant difference in infarct size amongst vehicle, 1, and 10 mg/kg treated animals: 22.9 ± 5.0, 16.7 ± 4.2, and 21.1 ± 4.1, respectively, one‐way anova [F(2,32) = 0.542, P = 0.587]. The MCAO induced a significant decline in neurological score in the vehicle group (from 14 to 7 at 24 h post‐MCAO) but this was not significantly affected by LY362321 at either dose. In conclusion, pretreatment with a low or high dose of the novel SERM LY362321 did not significantly influence cerebral blood flow, infarct volume, or sensorimotor function in rats exposed to transient MCAO.
Neurogenesis and Depression: Breakthrough or Blind Alley?
Authors: Herbert Joe
Published: February 2008

Pieces of evidence are emerging in support of the startling idea that the birth of new neurones in the adult brain in some way underlies major depression. Although there are intriguing parallels between factors that regulate neurogenesis and those predicting depression or its recovery, at this point, we should remain sceptical but allow cautious hope that more effective therapies may be suggested.
Caffeine‐induced hyperactivity in the horse: comparisons of drug and metabolite concentrations in blood and cerebrospinal fluid
Authors: VICKROY T. W. , CHANG S.‐K. , CHOU C.‐C.
Published: February 2008

The goals of this study were to elucidate the temporal and quantitative relationships between caffeine and its major bioactive metabolites in blood and cerebrospinal fluid (CSF) and to characterize the pharmacokinetic–pharmacodynamic relationship for caffeine‐induced changes in spontaneous locomotor activity in the horse. We hypothesized that caffeine and its metabolites distribute efficiently into the CSF to antagonize adenosine A1 and A2a receptors and that spontaneous locomotor activity correlates well with caffeine and/or metabolite concentrations in CSF and blood. A microdialysis system was developed to allow simultaneous monitoring of locomotor activity and collection of CSF and blood samples for pharmacokinetic analysis. CSF concentrations of caffeine and its metabolites were evaluated to determine the percentage of central adenosine receptor blockade by the established standard inhibition curves. Caffeine increased the spontaneous locomotor activity for up to 4 h in a dose‐dependent manner. After 3 mg/kg caffeine administration, blood caffeine concentration as well as locomotor activity increased sharply to near peak level while CSF caffeine concentrations exhibited a slow rise to a steady‐state 75 min later. High correlation coefficient was found between locomotor activity and caffeine concentrations in blood (R2 = 0.95) and in CSF (R2 = 0.93). At 3 mg/kg dosage, theophylline was the only detectable caffeine metabolite in the CSF. The concentrations reached in the CSF were sufficient to partially block central adenosine A1 (14% blockade) and A2a (11% blockade) receptors. There were no statistically significant differences between the pharmacokinetics of caffeine in the blood and CSF. This study provides novel evidence that locomotor stimulation in horses is closely correlated with caffeine concentrations in the blood and CSF and, furthermore, is consistent with blockade of central adenosine receptors.
Evidence for human‐mediated dispersal of exotic earthworms: support for exploring strategies to limit further spread
Authors: HALE CINDY M.
Published: February 2008

As potent ecosystem engineers, non‐native earthworms are altering the fundamental structure and function of previously earthworm‐free cold‐temperate hardwood forests in North America. Discarded earthworms used for fishing bait has been presumed to be an important vector for the continued spread of non‐native earthworms because epicentres of invasion often include boat landings, lakeshores and roads. However, controversy has remained about the overall importance of human‐mediated spread vs. natural expansion of established earthworm populations. In this issue of Molecular Ecology, Cameron et al. explore the continued role of humans in dispersing non‐native earthworms.
Female dispersal and male kinship–based association in southern hairy‐nosed wombats (Lasiorhinus latifrons)
Authors: WALKER FAITH M. , TAYLOR ANDREA C. , SUNNUCKS PAUL
Published: February 2008

Generalizations about sociobiology require investigations of species with diverse ecological roles and phylogenetic affiliations. The southern hairy‐nosed wombat (Lasiorhinus latifrons) is valuable here, in that it is a marsupial of semi‐arid habitat, and one of the largest burrowing herbivores (commonly attaining 26 kg). Its sociobiology is poorly understood because the species is nocturnal, shy, and difficult to observe or capture nondisruptively. To investigate aspects of the species’ sociobiology in continuous habitat, we applied high‐intensity, temporally replicated, noninvasive sampling and genotyping of hairs to identify individuals and their sex. Spatial relatedness (kinship) structure was estimated, and related to patterns of burrow‐use. To understand the association of kinship with burrow/warren‐sharing and preferential colocation between wombats, > 100 genetically ‘tagged’ individuals at Brookfield Conservation Park (Murraylands, South Australia) were ‘tracked’ through multiple seasons between 1999 and 2001. Dispersal was female‐biased, and may be performed by females after breeding. Conversely, males were philopatric. Male kin relationships were characterized by preferential burrow‐ and warren‐sharing among closely related males, often in associations lasting for years. In contrast, females under‐associated with their close female relatives and did not form matrilineal groupings with potential for favourable kin interactions. This fundamental departure from the predominant mammalian pattern raises questions about the origins and maintenance of the system, which is now known from all three species of wombat. The present study provides starting points to address those questions by adding to our knowledge of longitudinal spatiotemporal associations and habitat use of a marsupial with the unusual system of female‐biased dispersal, and by outlining robust methodologies.
Abscisic acid deficiency in the tomato mutant high‐pigment 3 leading to increased plastid number and higher fruit lycopene content
Authors: Galpaz Navot , Wang Qiang , Menda Naama , Zamir Dani , Hirschberg Joseph
Published: February 2008

Carotenoids are present in most tissues of higher plants where they play a variety of essential roles. To study the regulation of carotenoid biosynthesis, we have isolated novel mutations in tomato (Solanum lycopersicum) with altered pigmentation of fruit or flowers. Here we describe the isolation and analysis of a tomato mutant, high‐pigment 3 (hp3), that accumulates 30% more carotenoids in the mature fruit. Higher concentrations of carotenoids and chlorophyll were also measured in leaves and the pericarp of green fruit. The mutation in hp3 had occurred in the gene for zeaxanthin epoxidase (Zep), which converts zeaxanthin to violaxanthin. Consequently, leaves of the mutant lack violaxanthin and neoxanthin, and flowers contain only minute quantities of these xanthophylls. The concentration in the hp3 mutant of abscisic acid (ABA), which is derived from xanthophylls, is 75% lower than the normal level, making hp3 an ABA‐deficient mutant. The plastid compartment size in fruit cells is at least twofold larger in hp3 plants compared with the wild‐type. The transcript level in the green fruit of FtsZ, which encodes a tubulin‐like protein involved in plastid division, is 60% higher in hp3 than in the wild‐type, suggesting that increased plastid division is responsible for this phenomenon. Elevated fruit pigmentation and plastid compartment size were also observed in the ABA‐deficient mutants flacca and sitiens. Taken together, these results suggest that ABA deficiency in the tomato mutant hp3 leads to enlargement of the plastid compartment size, probably by increasing plastid division, thus enabling greater biosynthesis and a higher storage capacity of the pigments.
The pyruvate, orthophosphate dikinase regulatory proteins of Arabidopsis possess a novel, unprecedented Ser/Thr protein kinase primary structure
Authors: Chastain Chris J. , Xu Wenxin , Parsley Kate , Sarath Gautam , Hibberd Julian M. , Chollet Raymond
Published: February 2008

Pyruvate, orthophosphate dikinase (PPDK) is a ubiquitous, low‐abundance metabolic enzyme of undetermined function in C3 plants. Its activity in C3 chloroplasts is light‐regulated via reversible phosphorylation of an active‐site Thr residue by the PPDK regulatory protein (RP), a most unusual bifunctional protein kinase (PK)/protein phosphatase (PP). In this paper we document the molecular cloning and functional analysis of the two unique C3 RPs in Arabidopsis thaliana. The first of these, AtRP1, encodes a typical chloroplast‐targeted, bifunctional C4‐like RP. The second RP gene, AtRP2, encodes a monofunctional polypeptide that possesses in vitro RP‐like PK activity but lacks PP activity, and is localized in the cytosol. Notably, the deduced primary structures of these two highly homologous polypeptides are devoid of any canonical subdomain structure that unifies all known eukaryotic and prokaryotic Ser/Thr PKs into one of three superfamilies, despite the direct demonstration that AtRP1 is functionally a member of this group. Instead, these C3 RPs and the related C4 plant homologues encode a conserved, centrally positioned, approximately 260‐residue sequence currently described as the ‘domain of unknown function 299′ (DUF 299). We propose that vascular plant RPs form a unique protein kinase family now designated as the DUF 299 gene family.
The first zygotic division in Arabidopsis requires de novo transcription of thymidylate kinase
Authors: Ronceret Arnaud , Gadea‐Vacas Jose , Guilleminot Jocelyne , Lincker Frédéric , Delorme Valérie , Lahmy Sylvie , Pelletier Georges , Chabouté Marie‐Edith , Devic Martine
Published: February 2008

Re‐activation of cell division after fertilization involves the specific regulation of a set of genes. To identify genes involved in the gametophytic to sporophytic transition, we screened Arabidopsis T‐DNA insertion lines for early seed abortion at the zygote (zeus) or one‐cell embryo stages (cyclops), and characterized a sporophytic zygote‐lethal mutation, zeus1. ZEUS1 encodes a thymidylate kinase (AtTMPK) that synthesizes dTDP and is involved in the regulation of DNA replication. Unlike in yeast and animals, the single AtTMPK gene is capable of producing two proteins by alternative splicing; the longer isoform is targeted to the mitochondria, the shorter to the cytosol. Transcription of AtTMPK is activated during the G1/S‐phase transition of the cell cycle, similarly to yeast and mammalian orthologues. In AtTMPK:GUS plants, the reporter gene was preferentially expressed in cells undergoing division, but was not detected during the male and female gametophytic mitoses. GUS expression was observed in mature embryo sacs prior to fertilization, and this expression may indicate the time of synchronization of the gamete cell‐cycle phases. Identification of ZEU1 emphasizes the importance of control of the metabolism of DNA in the regulation of the G1/S‐phase transition at fertilization.
Regulation of the anthocyanin biosynthetic pathway by the TTG1/bHLH/Myb transcriptional complex in Arabidopsis seedlings
Authors: Gonzalez Antonio , Zhao Mingzhe , Leavitt John M. , Lloyd Alan M.
Published: February 2008

In all higher plants studied to date, the anthocyanin pigment pathway is regulated by a suite of transcription factors that include Myb, bHLH and WD‐repeat proteins. However, in Arabidopsis thaliana, the Myb regulators remain to be conclusively identified, and little is known about anthocyanin pathway regulation by TTG1‐dependent transcriptional complexes. Previous overexpression of the PAP1 Myb suggested that genes from the entire phenylpropanoid pathway are targets of regulation by Myb/bHLH/WD‐repeat complexes in Arabidopsis, in contrast to other plants. Here we demonstrate that overexpression of Myb113 or Myb114 results in substantial increases in pigment production similar to those previously seen as a result of over‐expression of PAP1, and pigment production in these overexpressors remains TTG1‐ and bHLH‐dependent. Also, plants harboring an RNAi construct targeting PAP1 and three Myb candidates (PAP2, Myb113 and Myb114) showed downregulated Myb gene expression and obvious anthocyanin deficiencies. Correlated with these anthocyanin deficiencies is downregulation of the same late anthocyanin structural genes that are downregulated in ttg1 and bHLH anthocyanin mutants. Expression studies using GL3:GR and TTG1:GR fusions revealed direct regulation of the late biosynthetic genes only. Functional diversification between GL3 and EGL3 with regard to activation of gene targets was revealed by GL3:GR studies in single and double bHLH mutant seedlings. Expression profiles for Myb and bHLH regulators are also presented in the context of pigment production in young seedlings.
ROXY1 and ROXY2, two Arabidopsis glutaredoxin genes, are required for anther development
Authors: Xing Shuping , Zachgo Sabine
Published: February 2008

Glutaredoxins (GRXs) are small oxidoreductases that are involved in various cellular processes and play a crucial role in responses to oxidative stress. Three GRX subgroups exist in plants, and GRXs with active sites of the CPYC and CGFS types are common to pro‐ and eukaryotes. In contrast, GRXs with the CC type motif have so far only been identified in land plants. Here, we report that the two CC‐type GRXs ROXY1 and ROXY2 together control anther development in Arabidopsis thaliana. Single roxy1 and roxy2 mutants are fertile and produce normal anthers. However, roxy1 roxy2 double mutants are sterile and do not produce pollen. Strikingly, abaxial and adaxial anther lobe differentiation are differently affected, with early lobe differentiation being defective in the adaxial lobes, whereas later steps during pollen mother cell differentiation are disrupted in the abaxial lobes. Expression studies show that ROXY1 and ROXY2 are expressed with overlapping patterns during anther development. Lack of ROXY1 and ROXY2 function affects a large number of anther genes at the transcriptional level. Genetic and RT‐PCR data imply that ROXY1/2 function downstream of the early‐acting anther gene SPOROCYTELESS/NOZZLE and upstream of DYSFUNCTIONAL TAPETUM1, controlling tapetum development. Mutagenesis of a conserved glutathione‐binding glycine in the ROXY1 protein indicates that CC‐type GRXs need to interact with glutathione to catalyze essential biosynthetic reactions. Analysis of these two novel anther genes indicates that redox regulation, as well as participating in plant stress defense mechanisms, might play a major role in the control of male gametogenesis.
SKP2A, an F‐box protein that regulates cell division, is degraded via the ubiquitin pathway
Authors: Jurado Silvia , Díaz‐Triviño Sara , Abraham Zamira , Manzano Concepción , Gutierrez Crisanto , Pozo Carlos del
Published: February 2008

Coordination between cell division and cell differentiation is crucial for growth and development of eukaryotic organisms. Progression through the different phases of cell division requires the specific degradation of proteins through the ubiquitin/proteasome 26S (Ub/26S) pathway. In plants, this pathway plays a key role in controlling several developmental processes and responses, including cell proliferation. SKP2A, an F‐box protein, regulates the stability of the cell division E2FC‐DPB transcription factor. Here, we show that the SKP2A forms a Skp, Cullin containing (SCF) complexin vivo that has E3 ubiquitin ligase activity. Interestingly, SKP2A is degraded through the Ub/26S pathway, and auxin regulates such degradation. SKP2A positively regulates cell division, at least in part by degrading the E2FC/DPB transcription repressor. Plants that overexpress SKP2A increase the number of cells in G2/M, reduce the level of ploidy and develop a higher number of lateral root primordia. Taken together, our results indicate that SKP2A is a positive regulator of cell division, and its stability is controlled by auxin‐dependent degradation.
Vascular endothelial growth factor overexpression in induced sputum of children with bronchial asthma
Authors: Hossny E. , El‐Awady H. , Bakr S. , Labib A.
Published: February 2008

Vascular endothelial growth factor (VEGF) induces angiogenesis and increases vascular permeability participating in narrowing of the airway lumen that follows lung injury. We sought to investigate the expression of VEGF in induced sputum during and after recovery from acute episodes of bronchial asthma in children. Eighteen asthmatic children with acute attacks of varying severity were subjected to VEGF estimation by an enzymatic immunoassay in induced sputum. They were followed up till complete remission of symptoms and signs and were then retested. VEGF was also estimated in sputum induced from age 34 and sex‐matched healthy children enrolled as a control group. The sputum VEGF levels during acute asthma [median = 71 ng/ml; mean (s.d.) = 114.6 (121.8) ng/ml] were significantly higher than the levels estimated during remission [median = 50 ng/ml; mean (s.d.) = 45.7 (24.2) ng/ml] and both were higher than the corresponding levels of the control group [median = 36 ng/ml; mean (s.d.) = 31.3 (17.2) ng/ml]. VEGF levels during asthmatic episodes correlated positively to the recovery levels (r = 0.6, p = 0.009). The patients’ VEGF expression did not vary with asthma severity, serum total IgE concentration, peripheral blood eosinophil count, or erythrocyte sedimentation rate of patients. Children on corticosteroids inhalation therapy at enrollment had sputum VEGF levels that were comparable to those on other therapies. The increased expression of sputum VEGF in asthmatic children reinforces the concept that it might have a pathogenetic role in bronchial asthma and may represent a biomarker of airway inflammation.
Bicarbonate transport and extracellular carbonic anhydrase in marine diatoms
Authors: Martin Cheryl L. , Tortell Philippe D.
Published: February 2008

In this article, we present new laboratory results examining the relative importance of HCO−3 transport and extracellular carbonic anhydrase (eCA) in 17 marine diatom species. We observed significant variability in both HCO−3 transport and eCA expression across a range of diatom species with different cell morphologies. All species we examined took up HCO−3 through a direct transport mechanism, with the fraction of HCO−3 transport ranging from 40 to 95% of total C uptake. eCA expression also varied significantly, with catalytic enhancement factors ranging approximately 10‐fold among species. There was a significant positive correlation between HCO−3 transport and eCA expression among the test species. However, neither HCO−3 transport nor eCA expression was significantly correlated to cell growth rates or surface area to volume ratios. We did observe weak positive trends between the ratio of C demand:supply and HCO−3 utilization/eCA expression, but these were not statistically significant. We are thus unable to provide a mechanistic explanation for the apparent variability in HCO−3 transport and eCA expression in marine diatoms. This variability may, nonetheless, have important implications for the physiological ecology of oceanic diatoms.