bluuebunny/crossref_metadata_2025_split huggingface dataset:
Eutrophication of lakes in urbanized areas: The case of Yaounde Municipal Lake in Cameroon, Central Africa
Authors: Kemka Norbert , Njiné Thomas , Togouet Serge Hubert Zébazé , Menbohan Samuel Foto , Nola Moïse , Monkiedje Adolphe , Niyitegeka Domitille , Compère Pierre 
Published: March 2006

AbstractA 1 year qualitative and quantitative evaluation of phytoplankton and chlorophyll‐a, as well as some physicochemical parameters, was recorded in a shallow tropical lake in Cameroon: the Yaounde Municipal Lake. Physicochemical measurements also were regularly made in its main tributary (Mingoa Stream). These analyses aimed to assess the lake's trophic status and to propose measures for controlling its degradation process. The Secchi disk transparency was low and rarely exceeded 100 cm. Conductivity was higher near the lake bottom. The oxygen deficiency, and sometimes anoxia, recorded from a 2.5 m depth leads to high quantities of ammonium‐nitrogen. The total phosphorus concentrations varied from 80–2290 µg P L−1 and the total Kjeldhal nitrogen concentrations fluctuated between 3 and 15 mg L−1. Upstream to the lake, in the Mingoa Stream, total phosphorus concentrations ranged from 0.6–3.8 mg P L−1 and total Kjeldhal nitrogen concentrations ranged from 10–22 mg L−1. There are up to 102 phytoplankton‐specific taxa, with Euglenophyta and Chlorophyta particularly more diversified. The phytoplankton biomass and chlorophyll‐a concentrations reached 225 µg mL−1 and 566 mg m−3, respectively. The analyses pointed out the allogenic nature of the functioning of this ecosystem as a result of bad waste management in the surrounding landscape. Urgent actions need to be undertaken in order to rehabilitate this lake, which rapidly shifted to a hypertrophic status.
Importance of life history studies for conservation of fragmented populations: A case study of the understory herb,Trillium camschatcense
Authors: OHARA MASASHI , TOMIMATSU HIROSHI , TAKADA TAKENORI , KAWANO SHOICHI 
Published: March 2006

AbstractTrillium camschatcenseis a common perennial woodland spring herb in Hokkaido, Japan. Anthropogenic land conversion (e.g. road construction and agricultural development) has resulted in a highly fragmented landscape with a large number of forest remnants andT. camschatcenseis now often found in the understory of small remnant forests surrounded by pastureland or agricultural fields in the Hidaka region, Hokkaido. Accordingly,T. camschatcensein this region must have experienced dramatic changes in population size and spatial distribution, which may have significantly reduced seed production and genetic diversity. First, we summarize a series of life history studies onT. camschatcense. Second, we introduce approaches to understand the effects of forest fragmentation on the understory herb,T. camschatcense. Finally, we conclude that integration of data on demographic, reproductive biology and genetic approaches is essential for plant conservation, and we emphasize that it is important to have basic life history data, such as long‐tem demographic data and variation in breeding system, on ‘common species’ before those species become ‘new rares’.
Role of sexual reproduction in the spread of an invasive clonal plant Solidago canadensis revealed using intersimple sequence repeat markers
Authors: DONG MEI , LU BAO‐RONG , ZHANG HONG‐BO , CHEN JIA‐KUAN , LI BO 
Published: March 2006

AbstractInvasive species, second only to habitat loss as a cause of biodiversity loss, pose serious threats to native biodiversity and ecosystems. Little is known about the mechanisms that some exotic plants use to become invasive in their non‐native ranges. Solidago canadensis, native to North America, was intentionally introduced to many countries where it has become an invasive plant. To understand the roles that reproductive mode plays in successful invasion of exotic plants, and the relative importance of sexual reproduction and clonal growth, the genetic diversity and clonal structure of two S. canadensis populations from Shanghai, China were investigated using intersimple sequence repeats. Samples were collected in a grid pattern with intervals of 2 m among adjacent individuals within the studied area (approximately 30 m × 30 m) for each population. Results showed that the percentages of polymorphic loci for the two populations were 97.9% and 96.5% and clonal diversity measured using the Simpson Diversity Index was 1.00 for both populations. No identical genotypes were found among the analyzed samples. It is suggested from this study that sexual reproduction facilitates the establishment of new S. canadensis populations, whereas clonal expansion maintains and enlarges the established populations. Thus, limiting sexual reproduction of S. canadensis may effectively control the invasion of this species.
Life‐history monographs of Japanese plants. 5: Trillium tschonoskii Maxim. (Trilliaceae)
Authors: OHARA MASASHI , KAWANO SHOICHI 
Published: March 2006

AbstractLife‐history characteristics and demography of Trillium tschonoskii (Trilliaceae) were studied and are described here. Trillium tschonoskii is the most wide‐ranging species among Asiatic Trillium, ranging from southern Sakhalin, the Japanese Islands (excepting Kyushu) to the Korean Peninsula, Taiwan and further to inland China and the Himalayas. The ecological range of T. tschonoskii is broad, extending from lowland forests to montane and further to subalpine mixed forests consisting of conifers and subalpine birch, Betula ermani. This species is a typical polycarpic perennial, similar to all other Japanese Trillium species, and flowers in early to late April in lowland populations and in mid‐June to early July in subalpine habitats. Trillium tschonoskii typically has three white petals and three sepals, and its pollinators are diverse, for example, flies, beetles and bees such as Scatophagiae (Diptera), Oedemera lucidicollis (Coleoptera) and Andrena sp. (Hymenoptera). Pollen/ovule ratios of T. tschonoskii are approximately 700, thus T. tschonoskii is potentially an inbreeder. Seed outputs per plant are variable, 29–190 (mean 85.0) in 1980, and 28–168 (mean 79.8) in 1984. Seeds with a large soft juicy elaiosome attract ants, which are effective dispersal agents, but nocturnal elaiosome predators, mainly ground beetles, are also very active. Our long‐term observations indicate that it takes approximately 10 years to reach a sexually mature stage and the life expectancy of mature plants is assumed to be exceedingly long, extending over 40 years.
Re‐examining the ontogeny of substantia nigra dopamine neurons
Authors: Gates Monte A. , Torres Eduardo M. , White Anna , Fricker‐Gates Rosemary A. , Dunnett Stephen B. 
Published: March 2006

AbstractRecently, the need to detail the precise ontogeny of nigrostriatal dopamine neurons has grown significantly. It is now thought that the gestational day on which the majority of these neurons are born is important not only for maximizing the yield of primary cells for transplantation but also for extracting suitable dopamine neural precursors (as stem cells) for expansion in vitro. Historically, peak ontogeny of substantia nigra pars compacta (SNc) dopamine neurons in the rat has been considered to occur around embryonic day (E)14. However, such a concept is at odds with recent studies that reveal not only that substantial numbers of tyrosine hydroxylase‐immunopositive cells reside in the ventral mesencephalic region of rats at E14 but that many of these cells have matured extensive axonal projections to the ventral forebrain. Here, then, the ontogeny of SNc neurons in rats commonly used as a source of donor tissue for experimental cell transplantation in animal models of Parkinson's disease has been re‐examined. Using a combination of bromodeoxyuridine (BrdU) administration at E11, E12, E13 or E14 with immunocytochemical stainings for both BrdU and tyrosine hydroxylase after 4 weeks of postnatal development, this characterization reveals that the vast majority (perhaps 80%) of SNc dopamine neurons are probably born on E12 in Sprague‐Dawley rats. Such findings are important in refining the use of embryonic tissues for primary cell transplantation and may provide more precise timing for identifying the cellular and molecular events that drive neural stem cells toward a dopaminergic phenotype during development.
Gene expression changes in thalamus and inferior colliculus associated with inflammation, cellular stress, metabolism and structural damage in thiamine deficiency
Authors: Vemuganti Raghu , Kalluri Haviryaji , Yi Jae‐Hyuk , Bowen Kellie K. , Hazell Alan S. 
Published: March 2006

AbstractIdentification of gene expression changes that promote focal neuronal death and neurological dysfunction can further our understanding of the pathophysiology of these disease states and could lead to new pharmacological and molecular therapies. Impairment of oxidative metabolism is a pathogenetic mechanism underlying neuronal death in many chronic neurodegenerative diseases as well as in Wernicke's encephalopathy (WE), a disorder induced by thiamine deficiency (TD). To identify functional pathways that lead to neuronal damage in this disorder, we have examined gene expression changes in the vulnerable thalamus and inferior colliculus of TD rats using Affymetrix Rat Genome GeneChip analysis in combination with gene ontology and functional categorization assessment utilizing the NetAffx GO Mining Tool. Of the 15 927 transcripts analysed, 125 in thalamus and 141 in inferior colliculus were more abundantly expressed in TD rats compared with control animals. In both regions, the major functional categories of transcripts that were increased in abundance after TD were those associated with inflammation (∼33%), stress (∼20%), cell death and repair (∼26%), and metabolic perturbation (∼19%), together constituting ∼98% of all transcripts up‐regulated. These changes occurred against a background of neuronal cell loss and reactive astro‐ and microgliosis in both structures. Our results indicate that (i) TD produces changes in gene expression that are consistent with the observed dysfunction and pathology, and (ii) similar alterations in expression occur in thalamus and inferior colliculus, brain regions previously considered to differ in pathology. These findings provide important new insight into processes responsible for lesion development in TD, and possibly WE.
Transmitter release face Ca2+ channel clusters persist at isolated presynaptic terminals
Authors: Sun Li , Li Qi , Khanna Rajesh , Chan Allen W. , Wong Fiona , Stanley Elise F. 
Published: March 2006

AbstractCa2+ influx through N‐type Ca2+ channels (CaV2.2) is known to be critical for transmitter release at many synapses. These channels are known to be localized to transmitter release sites, but their anchoring mechanism remains unknown. Recent studies have demonstrated that presynaptic organization is subject to interactions with the postsynaptic cell or the intervening extracellular matrix. We used a previously described high‐affinity antibody against the N‐type Ca2+ channels, Ab571, to localize Ca2+ channel clusters at the release face of an isolated giant calyx‐type synapse to test whether the maintenance of these clusters requires an intact extracellular matrix or contact with the postsynaptic cell. Because the number of Ca2+ channel clusters was unchanged after extracellular matrix dispersal or nerve terminal isolation, we conclude that presynaptic transmitter release face Ca2+ clusters can be maintained independently of extracellular influences. Our results suggest that a presynaptic molecular scaffold is responsible for the maintenance of release site Ca2+ channel clusters.
Transient expression of A‐type K+ channel α subunits Kv4.2 and Kv4.3 in rat spinal neurons during development
Authors: Huang Hsin‐Yi , Liao Chien‐Wei , Chen Pei‐Hsuan , Tsaur Meei‐Ling 
Published: March 2006

AbstractA‐type K+ currents (IAs) have been detected from the ventral horn neurons in rat spinal cord during embryonic day (E) 14 to postnatal day (P) 8 but not in adulthood. It is not known which types of neurons and which A‐type K+ channel α subunits express the IAs and what the possible function might be. Here, we examined the expression of two A‐type K+ channel α subunits, Kv4.2 and Kv4.3, in rat spinal cord at various developmental stages by immunohistochemistry. We found a transient expression of Kv4.2 in somatic motoneurons during E13.5–P8 with a peak around E17.5, which coincides temporally with the natural selection of motoneurons. Transient expression of Kv4.2 and Kv4.3 was also observed in the intermediate gray (IG) interneurons. During E19.5–P14, some IG interneurons express Kv4.2, some express Kv4.3 and a subset co‐express Kv4.2 and Kv4.3. Peak expression of Kv4.2 and Kv4.3 in the IG interneurons was detected around P1, which coincides temporally with the developmental selection of IG interneurons. In contrast to the IA‐expressing subunits Kv4.2 and Kv4.3, a delayed‐rectifier K+ channel α subunit Kv1.6 is persistently expressed in somatic motoneurons and IG interneurons. Together, these data support the hypothesis that expression of IAs may protect IA‐expressing somatic motoneurons, and possibly also IG interneurons, from naturally occurring cell death during developmental selection.
Intrauterine proximity to male fetuses affects the morphology of the sexually dimorphic nucleus of the preoptic area in the adult rat brain
Authors: Pei Minjuan , Matsuda Ken‐ichi , Sakamoto Hirotaka , Kawata Mitsuhiro 
Published: March 2006

AbstractPrevious studies on polytocous rodents have revealed that the fetal intrauterine position influences its later anatomy, physiology, reproductive performance and behavior. To investigate whether the position of a fetus in the uterus modifies the development of the brain, we examined whether the structure of the sexually dimorphic nucleus of the preoptic area (SDN‐POA) of rat brains accorded to their intrauterine positions. Brain sections of adult rats gestated between two male fetuses (2M) and between two female fetuses (2F) in the uterus were analysed for their immunoreactivity to calbindin‐D28k, which is a marker of the SDN‐POA. The SDN‐POA volume of the 2M adult males was greater than that of the 2F adult males, whereas the SDN‐POA volume of the 2M and 2F adult females showed no significant difference. This result indicated that contiguous male fetuses have a masculinizing effect on the SDN‐POA volume of the male. To further examine whether the increment of SDN‐POA volume in adulthood was due to exposure to elevated steroid hormones during fetal life, concentrations of testosterone and 17β‐estradiol in the brain were measured with 2M and 2F fetuses during gestation, respectively. On gestation day 21, the concentrations of testosterone and 17β‐estradiol in the brain were significantly higher in the 2M male rats as compared with the 2F male rats. The results suggested that there was a relationship between the fetal intrauterine position, hormone transfer from adjacent fetuses and the SDN‐POA volume in adult rat brains.
Clause boundaries in Old Hittite relative sentences1
Authors: Probert Philomen 
Published: March 2006

AbstractHittite relative sentences typically take the form ‘conjunction whichever slaves have run away, conjunction those we shall recover’. The first part (‘conj…away’) is known as the relative clause and the second (‘conj…recover’) as the resumptive clause. However, neither part is always introduced by a conjunction, and there is not always an explicit resumption (‘those’). This paper argues that in Old Hittite, and with exceptions under two well‐defined conditions, the resumption and the conjunction introducing the resumptive clause are strictly both present or both absent. The distinction between sentences with both and sentences with neither points to a structural distinction between adjoined and embedded relative clauses. After Old Hittite, it is no longer necessary for a resumptive clause to include either both resumption and conjunction or neither of these elements. The new possibilities suggest that the Old Hittite embedded relative clauses have been reanalysed as adjoined.
Teenage mothers’ anger over twelve years: partner conflict, partner transitions and children's anger
Authors: Jenkins Jennifer M. , Shapka Jennifer D. , Sorenson Ann M. 
Published: March 2006

Background:  This study examined the effects of maternal anger, partner transitions and partner conflict on later oppositional and angry behavior of the children of teenage mothers.Methods:  One hundred and twenty‐one teenage women were interviewed prior to the birth of the baby and at 3 points subsequently, when children were newborn, 7 years old and 12 years old. Child and teacher reports of children's oppositional behavior were obtained.Results:  Women who showed higher levels of anger at Time 1 experienced more conflict with partners and more partner transitions over the next 12 years than women with lower levels of anger. Partner conflict was a stronger predictor of children's oppositional and angry behavior than partner transitions. Maternal anger at Time 1 was associated with maternal anger at Time 4 but neither predicted children's oppositional behavior at Time 4.Conclusion:  There was support for the theoretical model that suggested that the personality characteristics of teenaged mothers confer some of their risk to children through children's exposure to the mothers’ problematic partner relationships.
Contractile activity of ATP and diadenosine tetraphosphate on urinary bladder in the rats: role of superoxide anion and urothelium
Authors: Khattab M. M. , Al‐Hrasen M. N. 
Published: March 2006

Summary 1 Both ATP and diadenosine tetraphosphate (AP4A) produced a dose‐dependent contraction of rat isolated urinary bladder rings. The AP4A dose–response curve was to the left of that of ATP, and the maximum response was greater than that produced by ATP. 2 Mechanical removal of the urothelium increased the contractile response to ATP by between 53% and 71%, and that to AP4A by 42% (at highest AP4A concentration) to 68% at lower concentration. 3 Inhibition of Cu/Zn superoxide dismutase with diethylthiocarbamate (DETCA, 5 mm) significantly reduced the ATP‐evoked contraction by 31% (at high ATP concentration) to 40% at low ATP concentration. Similarly, the AP4A‐induced contractions were significantly decreased by 27% at low AP4A level to 38% at higher concentrations. 4 Induction of exogenous superoxide anion stress by the use of the superoxide anion generator, pyrogallol (0.5 mm), significantly decreased both ATP‐ and AP4A‐induced contractions of the rat urinary bladder over the whole dose range. Contractile responses to ATP decreased by 36–40%, and those to AP4A by 44–49%. 5 In conclusion, the urinary bladder urothelium exerts an inhibitory control over the purinergic contractility produced by adenine mononucleotides and dinucleotides. Superoxide anion stress, whether endogenous or exogenous, attenuates the ATP‐induced as well as AP4A‐induced contractility.
Vasopressin receptor antagonists: pharmacological tools and potential therapeutic agents
Authors: Streefkerk J. O. , van Zwieten P. A. 
Published: March 2006

Summary 1  The present survey deals with the development and applications of non‐peptidergic vasopressin receptor antagonists. 2  The existence of at least three vasopressin receptors (V1, V2 and V3 respectively) is firmly established. 3  V1‐receptors play a relevant role in the regulation of vascular tone, whereas V2‐receptors are known to mediate the antidiuretic activity of vasopressin at the level of the renal collecting ducts. The V3‐receptor appears to be involved in the release of the adreno‐corticotropic hormone. 4  Vasopressin receptor antagonists which are peptides have been known for several decades, more recently, both V1‐ and V2‐receptor blockers which are non‐peptidergic have been introduced, as well as agents with affinity for both V1‐ and V2‐receptor subtypes. A survey of these non‐peptidergic antagonists is presented here. Such compounds are useful as pharmacological tools, and they can also be thought of as therapeutic agents as therapeutic agents in cardiovascular and renal diseases. 5  Selective V1‐ and V2‐receptor antagonists were used to study the interaction between vasopressin receptors and sympathetic neurones. Depending on the experimental model used this interaction can occur at either the pre‐ or postsynaptic sites. In both cases predominantly V1‐receptors are involved. 6  A brief survey is given of the potential use of V‐receptor antagonists in the drug therapy of syndrome of inappropriate antidiuretic hormone secretion and other water retaining disorders, congestive heart failure and certain forms of hypertension (in particular in the Negroid hypertensive patients).
The role of autacoids and the autonomic nervous system in cardiovascular responses to radio‐frequency energy heating
Authors: Jauchem J. R. 
Published: March 2006

Summary 1 Among the potential effects of exposure to high levels of radio‐frequency energy (RFE) (which includes microwaves), an increase in body temperature is the primary consequence. Release of autacoids and activity of the autonomic nervous system may influence (or be directly responsible for) some of the physiological changes that occur in conjunction with this hyperthermia. 2 The main focus of this review is the interaction of autacoids and the autonomic nervous system with cardiovascular changes during heating. Differences between environmental and RFE‐induced heating (such as rate of temperature change and degree of skin vs. core heating) may be important when considering these effects. 3 Antihistamines exhibited no beneficial effect on circulatory collapse during RFE‐induced heating. The serotonergic blocker methysergide decreased survival time in rats during terminal RFE exposure, despite no effects on heart rate (HR) or blood pressure. Although blockade of platelet‐activating factor resulted in lower HR before RFE exposure, there was a lack of effect on the subsequent increase in HR during heating. Nitric oxide did not contribute to the hypotension that occurs due to rapid heating by RFE exposure. There have been either no or very limited studies of effects of prostaglandins, bradykinin, or angiotensin on RFE‐induced heating responses. 4 β‐Adrenoceptor antagonism with propranolol resulted in significantly decreased survival times and lower final colonic temperatures during RFE exposure. A lack of effects of nadolol on survival time and temperature, coupled with its poor ability to traverse the blood–brain barrier, suggests that central β‐adrenergic stimulation rather than peripheral stimulation may alter thermoregulation. 5 Effects of the autonomic nervous system (as studied by adrenoceptor blockade) on potassium changes during heating have not been fully investigated. Such changes could be important in animals’ responses to RFE and other modalities of heating, and should be studied in future.