bluuebunny/crossref_metadata_2025 huggingface dataset:
The Selfish Brain And The Barker Hypothesis
Authors: Lumbers Eugenie R , Yu Ze‐Yan , Gibson Karen J
Published: March 2003

1. Brain sparing is a feature of intra‐uterine growth retardation (IUGR). This implies that there is a redistribution of metabolic supply so that body growth slows to a greater extent than brain growth.

2. Intra‐uterine growth retardation, as evidenced by a low birthweight for gestational age is a predisposing factor for hypertension, cardiovascular disease and diabetes mellitus in adult life.

3. In species like humans, nephrogenesis is complete before birth. In the rat, it is completed shortly after birth. In both species, it can be shown that either undernutrition or IUGR is associated with reduced nephron number.

4. It has been proposed that oligonephropathy results in hyperfiltration, which ultimately leads to glomerulosclerosis and hypertension. The renin–angiotensin system (RAS) is necessary for normal renal development and fetal renal function. In the rat, blockade of the RAS in the first weeks of life by pharmacological agents reduces glomerular number and has been shown to cause hypertension in adult life. Renal denervation reduces the activity of the fetal RAS and also causes abnormal development of the renin‐secreting cells.

5. There is tonic renal sympathetic nerve activity in the late gestation fetal sheep. The level of renal sympathetic nerve activity (RSNA) is influenced by the fetal behavioural state.

6. However, interactions between the developing kidney and the developing sympathetic nervous system are poorly understood. On the one hand, renal innervation may be important in the provision of neurotrophic factors that stimulate the development of the RAS and kidney. On the other, high levels of RSNA associated with circulating catecholamines and vasopressin may cause vasoconstriction and limit nephrogenesis. This latter effect could be a predisposing factor to adult hypertension and cardiovascular disease.
Characterization Of Lymphocyte β2‐Adrenoceptor Signalling In Patients With Left Ventricular Volume Overload Disease
Authors: Dzimiri Nduna , Basco Chona , Moorji Azadali , Afrane Barima , Al‐Halees Zohair
Published: March 2003

1. Studies using animal experimental models have suggested that the β2‐adrenoceptor
is uncoupled in association with alterations in the expression of G‐protein‐coupled
receptor kinases (GRK) 2/3 in heart failure. However, the functional expression of
the components of this pathway in human disease has not been fully elucidated yet.
In the present study, we evaluated the possibility that the regulation of β2‐adrenoceptor signalling components in patients with left ventricular volume overload (VOL) depends on the severity of the overload.

2. We characterized the lymphocyte GRK 2–6, β‐arrestins 1 and
2, β2‐adrenoceptor expression at the mRNA and protein levels, as well as the activity of adenylyl cyclase, protein kinases (PK) A and PKC in patients with VOL using healthy blood donors as controls.

3. In the patient group, GRK2 mRNA was increased by 61% (P <
0.001), GRK3 was increased by 54% (P < 0.005), GRK5 was increased
fivefold (P < 0.001) and the β‐arrestin 2 mRNA was increased
by 40% (P < 0.05). These increases were paralleled with a sixfold
increase in GRK2, a twofold increase in GRK3 and a 1.3‐fold increase in GRK5 protein
levels. These changes were associated with a significant decrease in β2‐adrenoceptor mRNA, the basal, catalytic and receptor‐mediated activity of adenylyl cyclase and sensitization of the forskolin‐stimulated activity towards augmented inhibition by guanylimidodiphosphate. In general, the increase in GRK2 and 5 mRNA exhibited a positive correlation with the gravity of the haemodynamic load, as determined by changes in left ventricular fractional shortening.

4. The results suggest that VOL induces an increase in the expression of lymphocyte β2‐adrenoceptor‐specific GRK and β‐arrestin 2
in association with an attenuation in β2‐adrenoceptor levels.
It can be speculated that the cardiac circulatory system adapts itself to altered
haemodynamic functional demands partly by altering β2‐adrenoceptor signalling.
A Comparative Study On The Activity Of Lansoprazole, Omeprazole And PD‐136450 On Acidified Ethanol‐ And Indomethacin‐Induced Gastric Lesions In The Rat
Authors: Chandranath SI , Bastaki SMA , Singh J
Published: March 2003

1. The proton pump inhibitors lansoprazole (LP) and omeprazole (OP) and the cholecystokinin (CCK)‐receptor antagonist PD‐136450 (PD) provide a broad spectrum of activities in their ability to inhibit gastric acid secretion and protect the stomach against ulcerogens. In the present study, we investigated the protective effects of these compounds against gastric ulcers induced by acidified ethanol (AE) and indomethacin.

2. Both AE (60% ethanol in 150 mmol/L HCl, 1 mL/rat) and indomethacin (30 mg/kg) produced gastric haemorrhagic lesions in the rat 1 and 6 h after oral administration, respectively.

3. The gastric mucosal protective effects of LP (1–20 mg/kg), OP (0.5–10 mg/kg) and PD (1–20 mg/kg), administered either orally or subcutaneously (s.c.) 30 min before the administration of AE or indomethacin, were dose dependent against both models of ulcer induction.

4. To determine whether the cytoprotective effect of LP, OP and PD (each 10 mg/kg) was mediated by endogenous prostaglandins (PG), indomethacin (10 mg/kg, s.c.) was administered 15 min before AE to inhibit prostanoids biosynthesis. Indomethacin reduced the cytoprotective effects of OP, but not LP, administered either orally or s.c. Indomethacin reduced the cytoprotective effect of PD administered orally, although the effect was much less significant than when PD was administered s.c. The results exclude the role of PG in mediating the protective effects of LP, whereas the possibility exists for PG to have a role in mediating the protective effects of OP and PD.

5. To investigate the possible involvement of endogenous nitric oxide (NO) in the cytoprotective action of LP, OP and PD, we treated rats with a selective inhibitor of NO synthesis, namely NG‐nitro‐L‐arginine methyl
ester (L‐NAME; 25 mg/kg, s.c.). Administration of L‐NAME
15 min prior to LP, OP or PD (each 10 mg/kg) orally or s.c. and challenge with AE
or indomethacin did not significantly increase the degree of the ulcer index and
L‐NAME was not able to antagonize the protective effects of LP, OP
and PD, thus excluding the role of NO in mediating the protective effects of these
drugs. However, the effects of PD in reducing the indomethacin‐induced ulcer index
were less significant in the presence than the absence of L‐NAME (P
< 0.05 vs P < 0.001, respectively), suggesting a role for NO.

6. In conclusion, the results of the present study suggest that LP and OP are equally effective against AE‐ as well as indomethacin‐induced gastric ulcers and were more potent than PD in protecting the stomach against ulcer formation. Lansoprazole, OP and PD bring about their cytoprotective action through the reduction of acid secretion and some other unknown mechanisms. However, OP and PD may exert their cytoprotective action through PG and NO pathways.
Potassium Channels Underlying The Resting Potential Of Pulmonary Artery Smooth Muscle Cells
Authors: Gurney Alison M , Osipenko Oleg N , MacMillan Debbi , Kempsill Fiona EJ
Published: March 2003

1. The molecular identity of the K channels giving rise to the negative membrane potential of pulmonary artery smooth muscle cells has yet to be determined.

2. To date, most studies have focused on voltage‐gated, delayed rectifier channels and their roles in mediating hypoxia‐induced membrane depolarization. There is, however, strong evidence that an outwardly rectifying K+ conductance distinct from the classical delayed rectifier is involved.

3. Growing evidence that TASK‐like channels can sense hypoxia and are present in pulmonary artery smooth muscle cells suggests that they may be responsible for the resting K+ conductance and resting potential.

4. The present review considers the evidence that particular K channels maintain the resting membrane potential of pulmonary artery smooth muscle cells and mediate the depolarizing response to hypoxia.
Effects Of Glycine On Glomerular Filtration Rate And Segmental Tubular Handling Of Sodium In Conscious Rats
Authors: Thomsen Klaus , Nielsen Camilla Birch , Flyvbjerg Allan
Published: March 2003

1. Infusion of the amino acid glycine leads to an increase in effective renal plasma flow (ERPF) and glomerular filtration rate (GFR) by a mechanism that possibly involves stimulation of nitric oxide (NO). Because NO also increases proximal tubular fluid output (Vprox) by inhibition of proximal tubular Na+ reabsorption and modulation of the tubuloglomerular feedback system, we hypothesized that glycine would increase Vprox as measured by lithium clearance (CLi).

2. In the first series of experiments, the effect of glycine infusion (4 mg/min) was examined in conscious, unstressed, chronically catheterized rats. In an additional series of experiments, the effect of glycine was examined under similar conditions in rats pretreated with a NO synthase (NOS) inhibitor (NG‐nitro‐L‐arginine methyl ester (L‐NAME), 2.5 μg/min).

3. Glycine significantly increased ERPF (from 3268 to 4018 μL/min per 100 g bodyweight (BW)), GFR (from 874 to 1009 μL/min per 100 g BW), CLi (from 275 to 461 μL/min per 100 g BW) and Na+ clearance (CNa; from 2.9 to 14.0 μL/min per 100 g BW). Fractional excretion of lithium (FELi; from 32 to 46%) and CNa/CLi (from 0.99 to 2.99%) also rose, indicating inhibition of proximal and distal nephron Na+ reabsorption, respectively. In the rats pretreated with L‐NAME, similar haemodynamic and tubular responses to glycine infusion were seen, suggesting that the effects were not mediated by NO.

4. We conclude, that glycine increases ERPF and GFR and it also inhibits proximal and distal nephron Na+ reabsorption leading to an increase in CLi and CNa. There was no indication that any of these effects were mediated by NO.
Bioactive proteins from stonefish venom
Authors: Khoo Hoon Eng
Published: March 2003

1. Of all the venomous fish known, the stonefish is one of the most commonly encountered by man. Studies on its venom started in the 1950s, but little work was performed after that until several groups revived interest in the venom in the 1980s after easier accessibility to the fish.

2. Stonefish venom is a mixture of proteins, containing several enzymes, including hyaluronidase of high specific activity. A purified stonefish hyaluronidase has been characterized.

3. Several of the effects of the crude venom have been isolated to a protein lethal factor that has cytolytic, neurotoxic and hypotensive activity. This protein is stonustoxin from Synanceja horrida, trachynilysin from Synanceja trachynis and verrucotoxin from Synanceja verrucosa.

4. The biochemical properties and activities of these protein lethal factors are reviewed.
Effects of sustained‐release tulobuterol on asthma control and β‐adrenoceptor function
Authors: Kume Hiroaki , Kondo Masashi , Ito Yasushi , Suzuki Ryujiro , Yamaki Kenichi , Takagi Kenzo
Published: March 2003

1. Recently, a patch formulation of tulobuterol, a β‐adrenoceptor (AR) agonist, has been developed using a transdermal delivery system. The present study was designed to determine whether β‐AR function and asthma control were affected by the sustained‐released β‐AR agonist.

2. Tulobuterol (2 mg) was applied daily for 8 weeks to seven patients with bronchial asthma in whom the morning dip in the peak expiratory flow (PEF) rate developed even though inhaled glucocorticoids were being taken. After treatment with tulobuterol, the early morning reduction in PEF was suppressed and PEF values were increased from 367 ± 35 to 439 ± 38 L/min (P < 0.05). The rescue use of inhaled β‐AR agonists was decreased from 6.9 ± 2.0 to 1.0 ± 0.7 puffs/week (P < 0.01). Symptom scores also decreased from 8.3 ± 3.4 to 2.1 ± 1.4 score/week (P < 0.01).

3. Next, we sought to examine the effects of exposure to tulobuterol on β‐AR function in guinea‐pig tracheal smooth muscle. After exposure of tissues to tulobuterol (0.01–10 µmol/L) for 45 min, the inhibitory effects of tulobuterol on methacholine‐induced contractions were attenuated in a concentration‐dependent manner. However, the inhibitory effects of tulobuterol were not affected after exposure to 0.01 µmol/L tulobuterol (a concentration greater than serum levels in clinical use). In contrast, the inhibitory effects of procaterol were not affected after exposure to tulobuterol under the same experimental conditions.

4. These results indicate that the combination of sustained‐released tulobuterol with inhaled glucocorticoid therapy is beneficial to patients with bronchial asthma who suffer from symptoms induced by the morning dip in PEF. Moreover, chronic exposure to lower concentrations of tulobuterol does not lead to desensitization of β‐AR in airway smooth muscle.
Functional organization of DNA elements regulating SM30α, a spicule matrix gene of sea urchin embryos
Authors: Yamasu Kyo , Wilt Fred H.
Published: March 2003

The SM30α gene encodes a protein in the embryonic endoskeleton of the sea urchin Strongylocentrotus purpuratus, and is specifically expressed in the skeletogenic primary mesenchyme cell lineage. To clarify the mechanism for the differentiation of this cell lineage, which proceeds rather autonomously in the embryo, regulation of the SM30α gene was investigated previously and it was shown that the distal DNA region upstream of this gene from − 1.6 to − 1.0 kb contained numerous negative regulatory elements that suppressed the ectopic expression of the gene in the gut. Here we study the influence of the proximal region from − 303 to + 104 bp. Analysis of the expression of reporter constructs indicated that a strong positive enhancer element existed in the region from − 142 to − 105 bp. This element worked both in forward and reverse orientations and additively when placed tandemly upstream to the reporter gene. In addition, other weaker positive and negative regulatory sites were also detected throughout the proximal region. Electrophoretic gel mobility shift analyses showed that multiple nuclear proteins were bound to the putative strong enhancer region. One of the proteins binding to this region was present in early blastulae, a time when the SM30 gene was still silent, but it was not in prism embryos actively expressing the gene. The binding region for this blastula‐specific protein was narrowed down to the region from − 132 to − 122 bp, which included the consensus binding site for the mammalian proto‐oncogene product, Ets. Two possible SpGCF1 binding sites were identified in the vicinity of the enhancer region. This information was used to make a comparison of the general regulatory architecture of genes that contribute to the formation of the skeletal spicule.
Purification and characterization of prolyl endopeptidase from the Pacific herring, Clupea pallasi, and its role in the activation of sperm motility
Authors: Yoshida Kaoru , Inaba Kazuo , Ohtake Hideki , Morisawa Masaaki
Published: March 2003

Protease activities with specificity toward synthetic substrates, Suc‐Gly‐Pro‐Leu‐Gly‐Pro‐MCA for prolyl endopeptidase or collagenase‐like peptidase, and Suc‐Ala‐Ala‐Pro‐Phe‐MCA for chymotrypsin were identified in the detergent‐soluble fraction of herring spermatozoa. The enzyme activities increased in the presence of herring sperm‐activating protein (HSAP). Among them a prolyl endopeptidase [EC. 3. 4. 21. 26] was purified to near homogeneity from herring testis. The molecular mass of the enzyme was 79 kDa and the properties of the enzyme were quite similar to prolyl endopeptidase from other tissues or cells. Both the enzyme activation and the sperm motility activation by HSAP were inhibited by benzyloxycarbonyl‐L‐thioproline‐thioprolinal, a specific inhibitor for prolyl endopeptidase. Furthermore, the motility activation by HSAP was inhibited by substrates of the prolyl endopeptidase. Western blotting with mouse anti‐prolyl endopeptidase serum revealed the presence of 79 kDa prolyl endopeptidase in the tail fraction of herring sperm. These results suggest that prolyl endopeptidase exists on the surface of the sperm tail and interacts with the HSAP.
Development of the skeleton in Japanese quail embryos
Authors: Nakane Yoshifumi , Tsudzuki Masaoki
Published: March 2003

In the research fields of experimental embryology, teratological testing, and developmental engineering in avian species, a knowledge of normal embryonic development is necessary so that research may be performed efficiently and precisely. A series of normal stages based on external appearance has been established in both chicken and quail embryos. Those based on skeletal features, however, have not been elucidated. The present study newly established a series of normal stages for the development of the Japanese quail embryo skeleton. This series is composed of 15 stages determined by observing the timing of chondrification and calcification of the skeleton every 24 h, from 3 to 17 days of incubation. Cartilage and ossified bones were stained blue and red with Alcian blue 8GX and alizarin red S, respectively. These skeletogenous stages of the Japanese quail embryo will be useful as a normal control not only in studies of experimental embryology, teratological testing, and developmental engineering, but also in the analysis of mutant embryos with skeletal abnormalities.
Ultrastructural studies on the centrosome‐attracting body: Electron‐dense matrix and its role in unequal cleavages in ascidian embryos
Authors: Iseto Tohru , Nishida Hiroki
Published: March 2003

In ascidian embryos, three successive unequal cleavages occur at the posterior pole, generating a specific cleavage pattern. A recently reported novel structure designated the centrosome‐attracting body (CAB) has been suggested to play essential roles in the unequal cleavages attracting centrosomes and the nucleus towards the posterior pole. To examine the morphological features of the CAB, the ultrastructure of the CAB of two ascidian species, Halocynthia roretzi and Ciona intestinalis was observed by transmission electron microscopy. Detailed observations clarified that the electron‐dense matrix (EDM) was a CAB‐specific component that was commonly observed in the CAB of both species but was not found in other areas of the embryo. Further observations of the CAB in various staged embryos revealed that the ultrastructure was quite stable, with no difference between points of a cell cycle or between each stage from the 8‐ to 64‐cell stage when unequal cleavage occurred. Observations of extracted embryos implied that the EDM was the extraction‐resistant component of the CAB and was tightly anchored to the plasma membrane. It has been proposed that the EDM functions as a physical attachment site at the cell cortex for microtubules emanating from centrosomes and provides a scaffold for the centrosome‐attracting machinery. Interestingly, the ultrastructure of the CAB resembled germ plasm reported in other animals, raising the possibility that the CAB‐containing posterior‐most blastomeres are germ‐ line precursors.
Reduction of intramembranous particles in the periacrosomal plasma membrane of boar spermatozoa during in vitro capacitation: A statistical study
Authors: Suzuki‐Toyota Fumie , Itoh Yoneto , Naito Kunihiko
Published: March 2003

Membrane remodeling in the periacrosomal plasma membrane (PAPM) of boar spermatozoa during incubation in capacitation medium was examined by the freeze‐fracture technique. In the preservation medium (PM) group, the major small (about 8 nm) intramembranous particles (IMP) and the minor large (> 10 nm) IMP were distributed evenly in the PAPM. The IMP‐free area increased during capacitation. To correct the IMP‐free area, arithmetically redistributed (ARD)‐IMP density was used for statistical analysis. In the PM group, the mean density ± SD of large IMP was 379 ± 64 and 266 ± 58/μm2, and that of small IMP was 1450 ± 155 and 672 ± 252/μm2 in protoplasmic (P) and external (E) faces, respectively. During capacitation, the significant (P < 0.01) reduction of large IMP density was encountered only in the E face of a few incubation groups, while that of the small IMP density occurred in the P face by 2 h. Consequently, reduction of the total IMP density of both faces was not significant in the large IMP, but it was significant (P < 0.01) in the small IMP. One‐fifth of the total small IMP density reduced by 2 h. Filipin‐sterol complexes (FSC) were numerous in the PAPM, and FSC‐free areas also increased during capacitation. The mechanism of IMP‐free area formation and the behavior of the small IMP in the PAPM during capacitation were discussed in relation to membrane stability.
IFN‐γ induces apoptosis in mouse embryonic stem cells, a putative mechanism of its embryotoxicity
Authors: Zou Gang‐Ming , Reznikoff‐Etievant Marie‐Françoise , Hirsch François , Milliez Jacques
Published: March 2003

It has been reported that interferon (IFN)‐γ should inhibit in vitro mouse embryo growth by direct cell toxicity. However, the mechanism involved has not been clearly established. In the present study, this question was addressed using the embryonic stem (ES) cell model. It was found that IFN‐γ induces a dose‐dependent apoptosis in ES cells, as assessed by trypan‐blue staining, by Annexin‐V labeling and DNA analysis. Moreover, IFN‐γ treatment cooperates with Fas‐mediated apoptosis, a phenomenon that has been recently reported. As Bcl‐2 oncoprotein functions as a death repressor molecule in an evolutionarily conserved cell death pathway, its expression was analyzed by flow cytometry. It was demonstrated that Bcl‐2 is expressed in ES cells. When compared to untreated ES cells, IFN‐γ‐treated, apoptotic cells expressed a lower Bcl‐2 level and a normal level of Fas, whereas surviving cells expressed a normal level of Bcl‐2 but a lower Fas expression. Altogether, these data suggest that IFN‐γ may influence early mouse embryo development by promoting apoptosis, which may constitute a novel mechanism of IFN‐γ embryotoxicity.
Sequential activation of transcription factors in lens induction
Authors: Ogino Hajime , Yasuda Kunio
Published: March 2003

Since the pioneering work of the early 1900s, the lens has been used as a model system for the study of tissue development in vertebrates. A number of embryological transplantation experiments designed to elucidate the role of tissue interactions in the formation of the lens have led to the proposal of a stepwise determination model. This model has recently been refined through the identification of certain transcription factor genes, which exhibit distinct expression patterns and functional properties in the lens cell lineage. Otx2, Pax6, and Lens1 are induced by the adjacent anterior neural plate and expressed in predifferentiated lens ectoderm. Contact between the optic vesicle and lens ectoderm promotes expression of mafs, Soxs, and Prox1, which are responsible for the initiation of lens differentiation programs including crystallin expression, cell elongation, and cell cycle arrest. Further analysis of the expression and functional characteristics of these transcription factors will allow greater detail when describing the orchestration of genetic programs, which control tissue development from induction to maturation.
Localization and behavior of putative blastopore determinants in the uncleaved Xenopus egg
Authors: Shinagawa Atsunori , Kobayashi Shunsuke
Published: March 2003

The present study examines putative blastopore determinants in uncleaved Xenopus eggs. Deletion of marginal and lower portions of Xenopus eggs when between 30 and 50% of the first cell cycle has been completed (0.3–0.5 normalized time (NT)) results in the complete absence of the blastopore, while deletion of the vegetal hemisphere during the same period leads to the formation of a smaller blastopore. Extrusion of only yolk and deep cytoplasm of the vegetal hemisphere during 0.3–0.5 NT does not affect the formation or size of the blastopore. Consistently, transplantation of cortical and subcortical cytoplasm from marginal, but not other, sites of eggs at 0.3–0.5 NT to an animal blastomere from 16‐cell stage embryos induces an ectopic blastopore and bottle cell‐like cells. This does not occur in the same transplantation from eggs at 0.2 NT. These results suggest that the blastopore determinants become localized to the marginal cortical and/or subcortical cytoplasm during 0.2–0.3 NT. Other results suggest the involvement of a hexyleneglycol‐sensitive system in the process of localization of the blastopore determinants to the marginal region during 0.2–0.3 NT. The properties and behavior of the putative blastopore determinants are discussed in relation to those of VegT, which previously has been shown to induce ectopic blastopores.
Role of a vitelline layer‐associated 350 kDa glycoprotein in controlling species‐specific gamete interaction in the sea urchin
Authors: Hirohashi Noritaka , Lennarz William J.
Published: March 2003

The process of sperm–egg binding is one of the barriers to cross‐fertilization between related sea urchin species. A 350 kDa glycoprotein in the egg vitelline layer of Strongylocentrotus purpuratus has been shown to be a sperm‐binding protein (SBP). Sulfated O‐linked oligosaccharide chains on the 350 kDa glycoprotein, as well as domains of the polypeptide chain, serve as ligands for this binding process. The hypothesis that species‐specific sperm–egg binding is attributed to the interaction between the sperm and the 350 kDa glycoprotein was tested using S. purpuratus and S. franciscanus. It was found that both species had a 350 kDa glycoprotein on the egg surface that cross‐reacted immunologically using antibodies prepared against a recombinant form of the SBP. Because earlier studies had implicated the carbohydrate chains of the 350 kDa glycoprotein of S purpuratus in sperm binding, differences in carbohydrate chains on the 350 kDa glycoproteins of these species were examined. It was found that among the lectins tested only wheat germ agglutinin and Sambucus nigra agglutinin showed a significant difference in reactivity to the 350 kDa glycoproteins between species. Finally, using a bead‐binding assay, it was shown that the isolated 350 kDa glycoproteins exhibited species‐specific sperm‐binding activity.
Behavior of pigment cells in gastrula‐stage embryos of Hemicentrotus pulcherrimus and Scaphechinus mirabilis
Authors: Kominami Tetsuya , Takata Hiromi , Takaichi Miho
Published: March 2003

The behavior of pigment cells in sea urchin embryos, especially at the gastrula stage, is not well understood, due to the lack of an appropriate method to detect pigment cells. We found that pigment cells emanated autofluorescence when they were fixed with formalin and irradiated with ultraviolet or green light. In Hemicentrotus pulcherrimus, fluorescent pigment cells became visible at the archenteron tip at the mid‐gastrula stage. The cells detached from the archenteron slightly before the initiation of secondary invagination and migrated toward the apical plate. Most pigment cells entered the apical plate. This entry site seemed to be restricted, because pigment cells could not enter the ectoderm and remained in the blastocoele at the vegetal pole side when elongation of archenteron was blocked. Pigment cells that had entered the apical plate soon began to migrate in the aboral ectoderm toward the vegetal pole. In contrast, pigment cells of Scaphechinus mirabilis embryos were first detected in the vegetal plate before the onset of gastrulation. Without entering the blastocoele, these cells began to migrate preferentially in the aboral ectoderm toward the animal pole. When the archenteron tip reached the apical plate, pigment cells had already distributed throughout the aboral ectoderm. Thus, the behavior of pigment cells was quite different between H. pulcherrimus and S. mirabilis..
The bone morphogenetic protein antagonist Noggin is regulated by Sox9 during endochondral differentiation
Authors: Zehentner Barbara Katharina , Haussmann Anja , Burtscher Helmut
Published: March 2003

Noggin has been described to be capable of binding bone morphogenetic proteins (BMP) and inhibiting BMP signaling by preventing the interactions of BMP with their receptors. Noggin expression during endochondral differentiation was analyzed to elucidate its potential role during chondrogenesis. Throughout mouse development, Noggin was expressed abundantly in the chondrocytic lineage as early as collagen type II RNA was detectable. In addition, a strong correlation was detected between Noggin expression and the expression profile of Sox9 during chondrogenesis. Sox9 (known to play an important role during chondrogenesis) and Noggin expression were investigated in the pluripotent mesenchymal cell line C3H10T1/2, stimulated by BMP‐2. BMP‐2 caused significant upregulation of Sox9 and Noggin expression in these cells. The upregulation of Noggin could be inhibited by introducing antisense oligonucleotides against Sox9 mRNA into the cells. Using mouse limb bud cultures, the role of Sox9 and Noggin during endochondral tissue differentiation was further studied. Treatment of cultures with Sox9 antisense oligonucleotides and/or Noggin protein caused significant alterations in limb morphogenesis and endochondral development. The data suggest that the transcriptional control of Noggin by Sox9 is a potent regulatory mechanism in chondrocyte differentiation.
Mutations of stonewall disrupt the maintenance of female germline stem cells in Drosophila melanogaster
Authors: Akiyama Takahiro
Published: March 2003

Germline stem cells located at the anterior tip of the adult Drosophila melanogaster ovary are critical to the continuous production of mature eggs. Following germline stem cell division, one daughter cell remains a stem cell, while the other becomes a cystoblast committed to differentiation. In this study it was shown that mutations in the putative transcription factor stonewall (stwl) disrupted the maintenance of female germline stem cells. The stwl mutations resulted in a loss of germline stem cells, causing a rapid decrease in egg chamber production. The egg chambers developed only to a limited extent before degenerating. The four mitotic cystocyte divisions were frequently inhibited by stwl mutations. Furthermore, some stwl germaria from newly emerged females completely lacked both stem cells and developing cysts and had a strong reduction in size. The argument is presented here that stwl is involved in the continuation of cell division during female germline development.
Antisense inhibition of Xbrachyury impairs mesoderm formation in Xenopus embryos
Authors: Giovannini Natalia , Rungger Duri
Published: March 2003

Expression of the Xbrachyury (Xbra) gene was inhibited by antisense RNA synthesized in situ from an expression vector read by RNA polymerase III, injected into the fertilized egg or the 2‐cell stage embryo of Xenopus laevis. Antisense‐treated embryos had markedly reduced levels of Xbra mRNA and protein, and showed deficiencies in mesodermal derivatives and axis formation. In particular, organization of the posterior axis was affected, but often the anterior axis was also reduced. Some embryos failed to form mesoderm altogether and remained amorphous. The antisense effect is dose‐dependent and may be ‘rescued’ by overexpression of Xbra. In Xbra‐deficient embryos, expression of several mesodermal genes (Xvent, pintallavis, Xlim, Xwnt‐8 and noggin) was reduced to varying degrees, whereas goosecoid levels remained normal. The modified expression levels were partly normalized when Xbra deficiency was rescued. The observation that antisense inhibition yields slightly different phenotypes from dominant‐negative inhibition suggests the recommendation of using several surrogate genetic approaches to determine the functional role of a gene in Xenopus development.
Developmental expression patterns of α1H T‐type Ca2+ channels during spermatogenesis and organogenesis in mice
Authors: Son Weon‐Young , Han Ching‐Tack , Lee Jae‐Ho , Jung Kyu‐Yong , Lee Hyoung‐Min , Choo Young‐Kug
Published: March 2003

The objectives of the present study were to investigate the expression patterns of T‐type Ca2+ channel mRNA during spermatogenesis and organogenesis in mice. Reverse transcription–polymerase chain reaction (RT–PCR) was performed to identify the subtypes of calcium channels present in the round spermatids isolated from mouse testes by flow cytometry. Transcripts of L‐type (α1D), non‐L‐type (α1E) and T‐type Ca2+ channels were detected in round spermatids. Analysis of PCR products of T‐type Ca2+ channels indicated that only α1H subunits were detected in round spermatids. The appearance and differential distribution of α1H T‐type Ca2+ channel mRNA during mouse spermatogenesis and postimplantation embryogenesis (embryonic (E) days E9, E12, E15) were investigated by in situ hybridization with digoxigenin‐labeled RNA probes coupled with alkaline phosphatase detection. In testes from adult and immature mice (postnatal 2 and 3 weeks), α1H T‐type Ca2+ channel mRNA was expressed in all developing germ cells and sertoli cells. On E9 and E12, tissues of the central nervous system, such as the telencephalon, expressed α1H T‐type Ca2+ channel mRNA. On E15, signals were detected throughout all organs of the embryo. These findings indicate that the expression of α1H T‐type Ca2+ channels is spatio‐temporally regulated during spermatogenesis and organogenesis.
Colonization of an artificial stream by fishes and aquatic macro‐invertebrates
Authors: Katano Osamu , Toi Jun‐ichi , Maekawa Koji , Iguchi Kei'ichiroh
Published: March 2003

We examined colonization by fishes and macro‐invertebrates from permanent streams into an artificial freshwater stream simulating lotic temporary bodies of water that exist for only a limited period each year. After introducing water, invertebrates such as chironomid larvae in mud increased in numbers rapidly in the experimental stream, although they were rare in mud in the permanent streams. Eleven of 12 fish species present in the permanent streams colonized the experimental stream and preyed upon invertebrates, although fish composition differed significantly between the two streams. About 100 days after the initiation of the experiment, both species richness and diversity in the experimental stream reached almost the same level as that in the permanent streams. More diverse fishes colonized the complex section where habitat diversity was high compared to the simple section in the experimental stream. Our study strongly suggests that lotic temporary waters such as temporary streams around main rivers have unique ecological characteristics and serve as valuable foraging sites for fish.
Patterns and mechanisms of transpiration in a large subalpine Norway spruce (Picea abies (L.) Karst.)
Authors: HERZOG KARLMARTIN , THUM ROLAND , KRONFUS GERHARD , HELDSTAB HANS‐JAKOB , HäSLER RUDOLF
Published: March 2003

In situ water relations of a large subalpine Norway spruce (Picea abies) were analyzed by simultaneous measurements of sap flow at different crown positions. In the diurnal scale, transpiration varied greatly, both spatially and temporally. Over longer periods, however, different parts of the crown transpired in fairly constant proportions. The average estimated transpiration was about 3.5 times greater in the upper than in the lower half and decreased 1.6‐fold from south to north. Water intercepted from rain, fog and dew buffered and significantly decreased the transpiration. The effect was strongest in those parts which were least coupled to the free atmosphere. The top of the crown seemed to experience a regular shortage of water shortly after starting transpiration, when it was forced to switch from internal reserves to sources in the soil. Further, lower branches then started transpiring, which may have led them to compete for the water. An enhanced nocturnal sap flow during warm and dry winds (Foehn) indicated that the tree also transpired at night. Shaded twigs had more capacity to intercept water externally than twigs in the sun. The significance of the crown structure for interaction with water in both liquid and vapour phases is discussed.
Effects of potential PAR on shoot extension in juveniles of the main tree species in a Japanese temperate forest
Authors: ISHIDA MEGUMI , PETERS Rob
Published: March 2003

We studied the relationship between potential photosynthetically active radiation (PAR), estimated from hemispherical photographs, and shoot extension rates of juveniles of 12 seral tree species. We distinguished between direct light site factor (DIR), diffuse light site factor (DIF), and gap light index (GLI). We used a log‐linear model to relate growth to DIR, DIF and GLI. Potential PAR explained shoot growth rates significantly in 33 cases out of 36 (12 species × 3 PAR). DIF explained the shoot extension rates better than DIR and GLI for 10 of the 12 species. The mean values of maximum shoot extension rates of the tolerant, the intermediate and the intolerant species were 52.4 cm year–1, 64.3 cm year–1 and 87.7 cm year–1, respectively. The maximum shoot extension rates of the tolerant and the intolerant species were recorded in about 50% DIF and more than 70% DIF, respectively. The minimum light level for seedling establishment of the intermediate and intolerant species was more than 20% DIF. We explained distribution characteristics and shoot extension of the species in relation to light in terms of shade tolerance. Predictions based on light‐growth curves and maximum growth curves were similar to field observations made elsewhere, suggesting that these models may be useful to predict extension growth of juvenile trees in mixed species stands.
Studies on litter decomposition processes in a temperate forest ecosystem. I. Change of organic matter in oak (Quercus liaotungensisKoidz.) twigs
Authors: HUANG JIAN‐HUI , HAN XING‐GUO , CHEN LING‐ZHI
Published: March 2003

The litter bag method was used in this study on the decomposition of twigs of an oak (Quercus liaotungensisKoidz.) which is dominant in the warm temperate deciduous forests. This continual 5‐year investigation was to measure the changes of organic compounds in twig litter. The decomposition of oak twigs based on rates of the mass loss during the first 5 years was simulated using the Olson exponential equation. The simulated data fitted well with the observed values. Oak twigs were predicted to reach 95% mass loss within 21 years. During the first 5 years, the concentration of protein in the remaining litter increased from 3.5% to 5.5%, while the concentration of hemicellulose decreased from 16.0% to 8.0%. However, there was no obvious change in the concentrations of lignin and cellulose. The losses of lignin, crude‐cellulose and hemicellulose could be well simulated using the Olson exponential equation. However, this was not true for cellulose and protein.
Estimation of the retention times and distances of seed dispersed by two monkey species, Alouatta seniculus and Lagothrix lagotricha, in a Colombian forest
Authors: Yumoto Takakazu , Kimura Koshin , Nishimura Akisato
Published: March 2003

Isolated‐bout method to estimate the retention times and dispersal distances was applied to the seed dispersal by red howler monkeys (Alouatta seniculus) and Humboldt’s woolly monkeys (Lagothrix lagotricha) in a lowland tropical forest at La Macarena, on the border of the Macarena and Tinigua National Parks, the Department of Meta, Colombia. Continuous observations were made on the feeding and ranging behavior of well‐habituated troops of howler monkeys and woolly monkeys as well as continuous collection of monkeys’ feces. We selected out the ‘isolated‐bout’ as a feeding bout on the specific species that was only once recorded within 48 h before the seeds of that species appeared in the feces of monkeys. In that case, the seeds were strongly suggested to come from that isolated bout. Then retention times, route seed dispersal distances and direct seed dispersal distances were estimated. Howler monkeys, which are regarded as generalist herbivores, showed longer retention times and dispersal distances along monkeys’ route than did woolly monkeys, which are specialist frugivores. However, the direct distances that seeds were carried from the mother tree were not significantly greater for howler monkeys than for woolly monkeys. This shows that both retention time and movement patterns by the monkeys, especially the total ranging area, influence the direct distance that seeds are carried from the mother tree.
Mixed leaf litter effects on decomposition rates and soil microarthropod communities in an oak–pine stand in Japan
Authors: Kaneko Nobuhiro , Salamanca Eric
Published: March 2003

Rates of decomposition, and soil faunal abundance and diversity associated with single‐species and mixed‐species litters were studied in a litter bag experiment in an oak–pine forest. We used two canopy species of leaf litter, pine and oak, and one shrub species, Sasa, and compared decomposition rates, and soil microarthropod abundance and community structure of oribatid mites in the litter bags. Mass loss of single species decreased in the order: oak > pine > Sasa. While the total mass loss rates of mixed litter were intermediate between those of the constituent species, enhancement of mass loss from the three‐species mixture and from mixed slow‐decomposing litters (pine and Sasa) was observed. Faunal abundance in litter bags was higher in mixed‐species litter than in those with single‐species litter, and species richness of oribatid mites was also higher in the three‐species mixed litter. Faunal abundance in single‐species litter bags was not correlated with mass loss, although enhancement of mass loss in mixed litter bags corresponded with higher microarthropod abundance. Habitat heterogeneity in mixed litter bags seemed to be responsible for the more abundant soil microarthropod community.
Topographical variations in a plant–soil system along a slope on Mt Ryuoh, Japan
Authors: Tokuchi Naoko , Takeda Hiroshi , Yoshida Kazuma , Iwatsubo Goro
Published: March 2003

The plant–soil system was studied at different topographic levels (i.e. ridge, backslope and footslope) along a slope in aCryptomeriaplantation. Soil solution chemistry at each representative topographic plot was investigated. Tree height and diameter ofCryptomeriadecreased upslope. The understory species composition changed along the slope. The upper part of the slope with Oa horizon soil N transformation was characterized by ammonification, while most of the inorganic N in the lower part of the slope without Oa horizon was nitrified. The inorganic N form in the soil solution corresponded with soil N transformation. Ammonium was the dominant inorganic N at the ridge, while NO3predominated at the foot of the slope. Soil solution chemistry was similar to throughfall at the ridge. At the foot slope, the chemical composition of the soil solution was different from throughfall due to high NO3−concentrations. This suggests that the inorganic N form regulated not only N concentration but also cation concentrations. The soil N transformation pattern is important in nutrient cycling.
Vegetation structure in gullies developed by the melting of ice wedges along Kolyma River, northern Siberia
Authors: Tsuyuzaki Shiro , Ishizaki Takeshi , Sato Toshiyuki
Published: March 2003

Vegetation structure was surveyed in gullies developed by the melting of ice wedges along the Kolyma River, northern Siberia, using 72 50 × 50 cm plots. The mean total plant cover was approximately 50% on gley soils, which were only distributed in the gullies. Based on TWINSPAN cluster analysis, four vegetation types were recognized: (i) Agrostis purpurascens grassland with Ceratodon purpureus moss carpet; (ii) Matricaria matricarioides forbland; (iii) Chamaenerium angustifolium and M. matricarioides forbland; and (iv) Descurainia sophia grassland. Species that produce seeds capable of long‐distance dispersal established well. Of the environmental factors surveyed, the gully scales (height and width) and elevational difference within a plot were primarily related to the vegetation development. The gully height was correlated with soil pH and compaction that might be related to intensities of ground surface disturbances. Agrostis purpurascens established in large gullies, while Equisetum arvense and Salix alaxensis established in small gullies. Soil compaction was also related to the vegetation establishment patterns (e.g. Rumex sibirica did not establish on hard soils). We concluded that the gully scales primarily determine soil conditions, including ground surface instability as a function of slope and soil compaction, and subsequent community structure.
Seasonal food habits of a sika deer population in the warm temperate forest of the westernmost part of Honshu, Japan
Authors: Jayasekara Palitha , Takatsuki Seiki
Published: March 2003

The rumen contents of 63 sika deer (Cervus nippon Temminck) shot in the westernmost part of Honshu were analyzed by the point‐frame method. The rumen contents were dominated by forbs and the majority of these were evergreen monocotyledonous plants, probably Ophiopogon spp. Evergreen browse leaves (woody leaves), such as Eurya japonica Thunb., Ilex crenata Thunb. and Trachelospermum asiaticum Nakai, were also important, constituting 20–40% of the rumen contents. Other categories accounted for only small proportions, although in summer, graminoids increased but twigs and bark decreased in importance and in fall and winter, fruits and seeds increased in importance. The diet of the deer was characterized by high‐quality foods even in winter and by a stability or less‐pronounced seasonality throughout the year than found in the northern deer. These results were compared with those from other populations, including a northern sika deer population in Japan.
Regeneration patterns in relation to canopy species composition and site variables in mixed oak forests in the Sierra de Manantlán Biosphere Reserve, Mexico
Authors: Figueroa‐Rangel Blanca Lorena , Olvera‐Vargas Miguel
Published: March 2003

Regeneration patterns in relation to canopy species composition and site variables were analyzed in mixed oak forests of the Sierra de Manantlán in western Mexico with the aim of establishing an ecological basis for the design of management alternatives. Using ordination (canonical correspondence analysis) and classification (two‐way indicator species analysis) methods, five different canopy types and three different seedling associations were revealed according to species composition, all of them dominated by one or more oak species. Red–far red ratio, slope, altitude, topography, canopy type and grazing intensity were the main variables that explained differences in species composition among the seedling associations. Oak seedlings were relatively scarce in the sampling plots, with the lowest frequency values of all species recorded except for those ofQuercus crassipesHumb. & Bonpl., and also the lowest density values. The presence of a particular oak seedling species was strongly associated with a particular percentage of canopy openness;Quercus candicansNée,Quercus laurinaHumb. & Bonpl. andQuercus rugosaNée were present in the plots with the least‐open canopy (6.4%, 2.9 and 6.2%, respectively), whileQuercus castaneaNée andQuercus crassipesHumb. & Bonpl. were present in the plots with the most‐open canopy (13 and 8.1%, respectively). Every oak seedling species was more frequent, although not dependent, on the canopy type where the same oak species dominated. Because of the great heterogeneity in species composition and the physiographical factors of mixed oak forests in the Sierra de Manantlán, we concluded that management alternatives must be prescribed for each ecological situation where the different oak species are growing.