bluuebunny/crossref_metadata_2025 huggingface dataset:
Genetic variation in drought hardiness of coastal Douglas-fir seedlings from British Columbia
Authors: Anekonda T S , Lomas M C , Adams W T , Kavanagh K L , Aitken S N
Published: November 2002

Genetic variation in drought hardiness traits and their genetic correlations with growth potential and recovery traits were investigated in 39 full-sib families of coastal Douglas-fir (Pseudotsuga menziesii var. menziesii (Mirb.) Franco) from southwestern British Columbia. Seedlings of these families were grown in raised nursery beds and subjected to three moisture regimes each in the second (well-watered or control, mild, and moderate drought) and third (control, severe drought, and recovery from second-year moderate drought) seasons. Traits assessed included drought hardiness (foliage damage, cavitation of xylem tracheids, xylem hydraulic conductivity, and height and diameter growth increment) in the drought treatments, growth potential (total height and diameter) in the control treatment, and height and diameter growth increments in the recovery treatment. Xylem cavitation in the growth ring produced in a particular year was nearly three times greater under the moderate drought and four times greater under the severe drought than in the control treatment. Xylem hydraulic conductivity of seedlings in the severe drought treatment was 40% lower than conductivity of seedlings under the control treatment. Mean foliage damage in seedlings subjected to severe drought (third season) was much greater (33%) than in seedlings subjected to mild or moderate drought (second season). Families differed significantly in most drought hardiness traits, with individual tree heritabilities averaging 0.19. Thus, much potential exists for identifying drought-hardy families at the seedling stage and using this information for deployment or breeding purposes. In addition, most hardiness traits were strongly intercorrelated (genetic correlations often exceeded |0.80|) indicating that these traits are controlled largely by the same set of genes and that selection for hardiness based on one trait will increase hardiness as reflected in the other traits as well. Genetic correlations were only moderate (0.49) between hardiness traits measured in different years, perhaps due to the large difference in severity of the drought applied in the two seasons. Although injury to seedlings, as reflected in foliage damage and xylem cavitation, was relatively low under the moderate drought of the second season, it did result in reduced growth increment the following (recovery) year. Growth potential under favorable moisture regimes was nearly uncorrelated with drought hardiness, suggesting that drought hardiness could be improved in this southwestern British Columbia breeding population without negatively impacting growth potential in favorable moisture conditions.
Abundance and species composition of amphibians, small mammals, and songbirds in riparian forest buffer strips of varying widths in the boreal mixedwood of Alberta
Authors: Hannon Susan J , Paszkowski Cynthia A , Boutin Stan , DeGroot Jordan , Macdonald S Ellen , Wheatley Matt , Eaton Brian R
Published: November 2002

Forested buffer strips are left along water bodies after forest harvesting to protect water quality and fish stocks, but little is known about their utility as reserves for forest species in managed landscapes. We report on changes in terrestrial vertebrate communities from pre- to post-harvest in experimentally created buffer strips (20, 100, 200, and 800 m wide) in a boreal mixedwood forest in Alberta, Canada. We trapped anuran amphibians and small mammals and spot-mapped bird territories around 12 lakes (4 treatment levels, 3 replicates) before and after harvesting. Changes in small mammal or amphibian abundance were not detected for any treatment relative to controls; however, these species are habitat generalists that used and even bred in clearcuts. Total bird abundance did not change after harvesting, with the exception of crowding in 20-m buffers 1 year post-harvest. Species composition did not change for amphibians and small mammals after harvest, but forest-dependent bird species declined as buffer width narrowed from 200 to 100 m and narrower. We concluded that 20100 m buffers would not serve as reserves for forest songbirds in managed landscapes, but that 200 m wide strips conserved the pre-harvest passerine bird community, at least up to 3 years post-harvest.
Field assessment of Douglas-fir somatic and zygotic seedlings with respect to gas exchange, water relations, and frost hardiness
Authors: Benowicz A , Grossnickle S C , El-Kassaby Y A
Published: November 2002

Douglas-fir (Pseudotsuga menziesii var. menziesii (Mirb.) Franco) zygotic seedlings and seedlings produced through somatic embryogenesis were grown in a field test on southern Vancouver Island, British Columbia. The two stock types were compared in a number of adaptive attributes evaluated during two growing seasons (1999 and 2000). The attributes were related to gas exchange, water relations, phenology, and fall frost hardiness. In both years, somatic and zygotic seedlings had similar rates of net photosynthesis in optimum and reduced light conditions, similar mesophyll conductance, and dark respiration rates. Small differences (P [Formula: see text] 0.05) were found for water relation attributes measured on irrigated plants: intrinsic water use efficiency (WUEi), transpiration (E), stomatal conductance (gwv) and midday xylem water potential (Ψ). Somatic seedlings had marginally higher E and gwv and lower Ψ in 2000 and lower WUEi in 1999 and 2000. Zygotic seedlings had higher WUEi because of their lower gwv while maintaining the same rates of net photosynthesis as somatic seedlings. There were no differences between somatic and zygotic seedlings in frost hardiness throughout the fall. Zygotic and somatic seedlings had similar timing of spring bud break pointing to a comparable level of spring frost hardiness in both stock types. Findings from this study indicate that somatic and zygotic seedlings had a similar pattern of physiological performance throughout 2 years of assessment.
Effects of liming and fertilization (N, PK) on stem growth, crown transparency, and needle element concentrations of Picea abies stands in southwestern Sweden
Authors: Sikström Ulf
Published: November 2002

Liming and (or) application of specific nutrients have been proposed as countermeasures to the acidification of forest soils in southern Sweden. The aim of this study was to investigate whether stem growth, crown transparency, and needle element concentrations of Picea abies (L.) Karst. growing on acidic mineral soils in southwestern Sweden are affected by additions of lime, lime plus P and K, or N in low doses (treatments: CaPK, Ca, N, CaPKN, and 2Ca2P2K). During the 5-year observation period following treatment with CaPKN there was a tendency to increased stem growth (possibly overestimated). The most plausible cause of this growth response was increased N availability in the soil, although the possibility that there was a minor effect of the PK application could not be excluded. None of the treatments affected the crown transparency. Several significant changes in elemental concentrations of current-year needles were associated with the treatments. The control plots in the experimental stands showed no severe damage or nutrient deficiencies despite the relatively acidic soils. These findings, together with the small treatment effects, suggest that there is no acute need for liming and (or) PK addition in P. abies stands on similar sites in southwestern Sweden.
The dendroclimatic signal in Douglas-fir and ponderosa pine tree-ring chronologies from the southern Canadian Cordillera
Authors: Watson Emma , Luckman Brian H
Published: November 2002

A network of 53 ring-width chronologies has been developed from low-elevation stands of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco, n = 40) and ponderosa pine (Pinus ponderosa Dougl. ex P. & C. Laws., n = 13) in the southern Canadian Cordillera. Relationships between the chronologies and monthly, seasonal, and annualized climatic parameters (precipitation, temperature, and Palmer Drought Severity Index (PDSI)) were investigated using correlation analyses. The results indicate that tree growth at the sites is most strongly related to water availability during the growing season months. Although the response of the two species is similar, Douglas-fir show a slightly stronger correlation with seasonalized precipitation for the prior year and early summer whereas ponderosa pine correlate most strongly with current year and late (July) summer precipitation. Maximum correlations for both species occur with annual precipitation totals. The precipitation signal is slightly weaker in the more northerly Douglas-fir chronologies in British Columbia and the higher elevation sites in southwestern Alberta. Correlations with available PDSI records are generally comparable with those from precipitation variables, but the limited number of PDSI records and the availability of more proximal and better correlated precipitation records indicated that annual (summersummer) precipitation totals provide the best possibilities to develop regional, moisture-related proxy climate records from these data. Analysis of earlywood and latewood chronologies for 28 sites (mainly Douglas-fir) indicates that earlywood width is most consistently and strongly correlated with precipitation in the previous summer (July and August), and latewood width is more strongly related to precipitation in the current summer (June and July). The results of these analyses demonstrate considerable potential for reconstructing annual (and (or) summer) precipitation for sites across the region.
Variation in overstory nitrogen uptake in a small, high-elevation southern Appalachian spruce-fir watershed
Authors: Barker M , Miegroet H Van , Nicholas N S , Creed I F
Published: November 2002

High-elevation red spruce (Picea rubens Sarg.)  Fraser fir (Abies fraseri (Pursh) Poir.) forests of the southern Appalachians exhibit considerable spatial heterogeneity in structure, and possibly in N uptake, because of a combination of natural disturbances and heavy fir mortality caused by infestations of the exotic balsam woolly adelgid (Adelges piceae Ratz). The objectives of this study are to determine spatial variability in tree N uptake in a small high-elevation catchment in the Great Smoky Mountains National Park, compare outcomes among calculation methods, and assess the influence of stand and landscape properties on N uptake. Tree N uptake is estimated for fifty 20 × 20 m plots in the Noland Divide Watershed (NDW). Components considered in the calculations are stem growth, foliage increment, and mortality of spruce, fir, and yellow birch (Betula alleghaniensis Britt.) from 1993 and 1998 stand inventories; throughfall N flux measured in summers 1998 and 1999; litterfall N return for 1 year in a subset of 12 plots; tissue N analyses; and atmospheric N deposition and root turnover estimates from the literature. Overstory N uptake varies spatially within NDW, with a CV of 941% depending on the calculation method. Variability among methods is even higher, with an almost 15-fold difference between the smallest and largest average overstory uptake estimate (5 vs. 74 kg·ha1·year1). Only 5 and 3 kg·ha1·year1of N is sequestered in wood and foliar increment, respectively, while 36 kg·ha1of N returns annually as aboveground litterfall. Uptake and its components are correlated with measures of stand structure but not with elevation or aspect.
Interspecific competition for nitrogen between early successional species and planted white spruce and jack pine seedlings
Authors: Hangs Ryan D , Knight J Diane , Van Rees Ken CJ
Published: November 2002

Relatively little is known about belowground competition for nitrogen (N) between boreal forest species. The objective of this study was to compare the relative competitiveness of three early successional boreal forest species, trembling aspen (Populus tremuloides Michx.), fireweed (Epilobium angustifolium L.), and calamagrostis (Calamagrostis canadensis (Michx.) Beauv.), on 15N uptake and the growth response by containerized white spruce (Picea glauca (Moench) Voss) and jack pine (Pinus banksiana Lamb.) seedlings. Three densities (0, 2, and 6 plants/pot) of each competitor species were interplanted with individual seedlings in pots with 15N-labelled fertilizer and grown for 3 months. The conifer seedlings had the greatest fertilizer 15N uptake (129.5 and 82.3 µg/m2 root for white spruce and jack pine, respectively) when grown in monoculture and the lowest uptake when interplanted with six competitor plants (9.2 and 8.6 µg/m2 root for white spruce and jack pine, respectively). Whether grown in monoculture or with conifer seedlings, calamagrostis took up the greatest amount of fertilizer 15N. Vegetation management practices that reduce the establishment of this grass species in the field should benefit N uptake and growth of outplanted white spruce and jack pine seedlings.
A new way to account for the effect of source-sink spatial relationships in whole plant carbon allocation models
Authors: Lacointe André , Isebrands J G , Host George E
Published: November 2002

To improve sourcesink relationship based carbon-allocation models, the basic proportional model was extended to account for a well-known effect of individual source to sink distances: among different sinks of similar characteristics, the more distant from the source, the lower the allocation coefficient. This was achieved through multiplication of the sink strength value by a coefficient that is proportional to a decreasing, simple function of distance, f; the power form was chosen for both simplicity and theoretical reasons. The resulting model was parameterized and evaluated on the empirical allocation matrix of the ECOPHYS model, after grouping together several individual, small sinks of similar nature and close location to remove any phyllotaxy-related bias. Both goodness of fit and predictive value were significantly improved compared with the basic proportional model (f = constant). The f-extended model yielded even better results if segments of different nature or age on the source to sink pathway were assigned different weights in the expression of distance, whereas the default expression of f, with an exponent of 1 and no additive constant, was optimal with no further parameter required. Thus, only 7 parameters (3 for pathway segment weights and 4 for sink strength values) were sufficient to retrieve the original 68 independent experimental allocation coefficients with a reasonable degree of accuracy. Pathway segment weights likely reflect both intrinsic transport pathway properties and situation within the plant architecture; this is discussed in relation to the possibilities of generalization and practical use of the model.
A 10 000 year local forest fire history in a dry heath forest site in eastern Finland, reconstructed from charcoal layer records of a small mire
Authors: Pitkänen Aki , Huttunen Pertti , Jungner Högne , Tolonen Kimmo
Published: November 2002

Local fire history covering the entire Holocene period at a dry forest site in North Karelia, eastern Finland (ca. 63°07' N, 30°44' E), was reconstructed on the basis of visible charcoal layers from peat deposits of a small mire basin. Seven points studied along a transect a few metres long provided a record of ancient local forest fires that had scarred the margin of the peat deposit. The charcoal layer records indicate a drastic increase in forest fires about 500 years ago compared with the earlier part of the Holocene period. During the past 500 years, human influence has been extensive in the area, and there have been 9 local fires during that period, while during the previous 9500 years there had been only 34 fires. Between the establishment of spruce (Picea abies (L.) Karst.) 6300 calendar years B.P. and the beginning of significant human influence, the site had burned over at a mean interval of 220260 years. The data indicate a decrease in fire frequency associated with a warm climate between 9000 and 6300 calendar years BP. This suggests that climatic warming does not necessarily result in increased frequency of forest fires.
Time since death and fall of Norway spruce logs in old-growth and selectively cut boreal forest
Authors: Storaunet Ken Olaf , Rolstad Jørund
Published: November 2002

To estimate the age of Norway spruce (Picea abies (L.) Karst.) logs by means of decay classes, and to assess how long it takes for downed logs to decompose, we dated logs dendrochronologically by applying 5- and 8-grade decay classification systems. Study sites were chosen in old-growth and previously selectively cut forest stands in boreal south-central Scandinavia; 113 logs were dated to the number of years since death, 120 were dated to the number of years since fall, and 61 logs were dated to both. The number of years from death to fall showed a negative exponential distribution, with a mean of 22 years and a range of 091 years. Decay classes of logs (8-grade scale) reflected time since fall (R2 = 0.58) better than time since death (R2 = 0.27) in a linear regression model. This result is due to the lower decomposition rate of standing snags. Therefore, the decomposition time of logs should be divided into two periods: time from death to fall, which varies considerably, and time after fall, which appears to follow a linear relationship with decay class. The model predicted that it takes 100 years after fall for downed logs to decompose completely (reaching decay class 8) in old-growth stands. Logs in selectively cut stands appeared to decompose faster (64 years), which is explained by a sample shortage of old logs resulting from previous cuttings. We conclude that the decomposition time of downed logs may be severely underestimated when data is retrospectively compiled from previously logged forest stands.
ACEH/ACE2 is a novel mammalian metallocarboxypeptidase and a homologue of angiotensin-converting enzyme insensitive to ACE inhibitors
Authors: Turner Anthony J , Tipnis Sarah R , Guy Jodie L , Rice Gillian I , Hooper Nigel M
Published: November 2002

A human zinc metalloprotease (termed ACEH or ACE2) with considerable homology to angiotensin- converting enzyme (ACE) (EC 3.4.15.1) has been identified and subsequently cloned and functionally expressed. The translated protein contains an N-terminal signal sequence, a single catalytic domain with zinc-binding motif (HEMGH), a transmembrane region, and a small C-terminal cytosolic domain. Unlike somatic ACE, ACEH functions as a carboxypeptidase when acting on angiotensin I and angiotensin II or other peptide substrates. ACEH may function in conjunction with ACE and neprilysin in novel pathways of angiotensin metabolism of physiological significance. In contrast with ACE, ACEH does not hydrolyse bradykinin and is not inhibited by typical ACE inhibitors. ACEH is unique among mammalian carboxypeptidases in containing an HEXXH zinc motif but, in this respect, resembles a bacterial enzyme, Thermus aquaticus (Taq) carboxypeptidase (EC 3.4.17.19). Collectrin, a developmentally regulated renal protein, is homologous with the C-terminal region of ACEH but has no similarity with ACE and no catalytic domain. Thus, the ACEH protein may have evolved as a chimera of a single ACE-like domain and a collectrin domain. The collectrin domain may regulate tissue response to injury whereas the catalytic domain is involved in peptide processing events.Key words: ACEH, ACE2, metalloprotease, collectrin, carboxypeptidase, angiotensin II.
In vitro and in vivo activity of analogues of the kinin B2 receptor antagonist MEN11270
Authors: Meini S , Lecci A , Carini F , Tramontana M , Giuliani S , Maggi C A , Ricci R , Fabbri G , Anichini B , Harmat N , Rizzi A , Camarda V , Regoli D , Quartara L
Published: November 2002

In this study, we describe the in vitro and in vivo activities of a series of cyclic peptide analogues of the selective kinin B2 receptor antagonist MEN11270 on Chinese hamster ovary cells expressing the human B2 receptor (hB2R), the human isolated umbilical vein (hUV), the isolated guinea pig ileum (gpI), and bradykinin (BK) induced bronchoconstriction (BC) and hypotension in anaesthetized guinea pigs. Substitutions in the backbone of MEN11270 (H-DArg-Arg-Pro-Hyp-Gly-Thi-c(Dab-DTic-Oic-Arg)c(7γ-10α)) aimed to increase the potency in inhibiting bronchospasm versus hypotension following the topical (intratracheal (i.t.)) or systemic (intravenous (i.v.)) application of these antagonists. A series of analogues were left unprotected from N-terminal cleavage by aminopeptidases (MEN12739, MEN13052, MEN13346, and MEN13371): these compounds maintained sizeable affinities for the hB2R (pKi = 9.4, 9.6, 9.7, and 8.6, respectively) and antagonist activities toward BK in the hUV (pA2 = 7.9, 8.3, 8.2, and 7.5) and gpI assays (pKB = 7.4, 7.8, 7.9, and 7.9), but the inhibition of BK-induced BC and hypotension in vivo was negligible following either i.v. or i.t. administration. Two analogues (MEN12388 and MEN13405) could be potential substrates of angiotensin-converting enzyme: these have good activity in the hB2R (pKi = 9.5 and 8.9, respectively), hUV (pA2 = 8.2 for MEN12388), and gpI assays (pKB = 8.4 and 8.0) but an in vivo activity 10- to 30-fold lower than the parent compound MEN11270 (pKi = 9.4, pA2 = 8.1, pKB = 8.3) when given by either the i.v. or the i.t. route. Other analogues were functionalized with a quaternary ammonium Lys derivative (MEN13031, MEN12374, and the previously mentioned MEN13052) or with an ethyl group on Arg (MEN13655 and the previously mentioned MEN13346 and MEN13405) in order to hinder or facilitate local absorption. MEN13346 and MEN13031 (pKi = 9.7and 9.5, pA2 = 8.2 and 7.9, pKB = 7.9 and 8.5, respectively) were 10- to 30-fold less active in vivo than MEN11270, without improving the discrimination between BK-induced BC and hypotension after either systemic or topical administration. It is concluded that the decreased in vivo activities of cyclic analogues of MEN11270 on BK-induced BC and hypotension following either their intratracheal or their intravenous routes of administration might be due in large part to metabolic degradation.Key words: bradykinin, asthma, blood pressure, guinea pig, metabolism.
Induction of B1 receptors in streptozotocin diabetic rats: possible involvement in the control of hyperglycemia-induced glomerular Erk 1 and 2 phosphorylation
Authors: Mage Marilyne , Pécher Christiane , Neau Eric , Cellier Eric , Dos Reiss Marina L , Schanstra Joost P , Couture Réjean , Bascands Jean-Loup , Girolami Jean-Pierre
Published: November 2002

We investigated the effects of a 3-week treatment with various combinations of angiotensin-converting enzyme inhibitor (ACEI) and B1 and B2 bradykinin receptor (B1R and B2R) antagonists (B1A and B2A) and AT1 receptor antagonist on ERK 1 and 2 phosphorylation in isolated glomeruli from streptozotocin-treated diabetic rats (STZ rats). Body weight, glycemia, and blood pressure were monitored. The rats were divided into nine groups: (1) control; and groups 29 were STZ treated with (3) insulin, (4) ACEI, (5) ACEI + B1A, (6) ACEI + B2A, (7) B2A, (8) B1A, (9) AT1 antagonist. ERK 1 and 2 phosphorylation and expression of B1R and B2R were assessed by Western blot analysis. ERK 1 and 2 phosphorylation was higher in STZ rats; this activation was normalized by insulin and reduced by ACEI but not by AT1 antagonist. The reduction of ERK 1 and 2 phosphorylation by the ACEI was reversed by B1A and B2A. The induction of B1R was confirmed by increased expression of mRNA and B1 receptor protein. Since ERK 1 and 2 phosphorylation is an early event in the induction of matrix secretion and hyperproliferation associated with diabetic nephropathy, activation of B1R and B2R appears to be a useful pharmacological target in the management of this pathology.Key words: kidney, type 1 diabetes, kinin receptors, ERK 1 and 2 phosphorylation, converting enzyme inhibitor.
Bradykinin-related compounds as new drugs for cancer and inflammation
Authors: Stewart John M , Gera Lajos , Chan Daniel C , Bunn Jr. Paul A , York Eunice J , Simkeviciene Vitalija , Helfrich Barbara
Published: November 2002

Bradykinin (BK) (Arg-Pro-Pro-Gly-Phe-Ser-Pro-Phe-Arg) is an important growth factor for small-cell lung cancer (SCLC) and prostate cancer (PC). These cancers have cells of neuroendocrine origin and express receptors for a variety of neuropeptides. BK receptors are expressed on almost all lung cancer cell lines and on many PC cells. Our very potent BK antagonist B9430 (D-Arg-Arg-Pro-Hyp-Gly-Igl-Ser-D-Igl-Oic-Arg) (Hyp, trans-4-hydroxy-L-proline; Igl, α-2-indanylglycine; Oic, octahydroindole-2-carboxylic acid) is a candidate anti-inflammatory drug but does not inhibit growth of SCLC or PC. When B9430 is dimerized by N-terminal cross-linking with a suberimide linker, the product B9870 is a potent growth inhibitor for SCLC both in vitro and in vivo in athymic nude mice. Daily i.p. injection at 5 mg·kg1·day1 beginning on day 8 after SCLC SHP-77 cell implantation gave 65% inhibition of tumor growth. B9870 stimulates apoptosis in SCLC by a novel "biased agonist" action. We have also developed new small mimetic antagonists. BKM-570 (F5C-OC2Y-Atmp) (F5C, pentafluorocinnamic acid; OC2Y, O-2,6-dichlorobenzyl tyrosine; Atmp, 4-amino-2,2,6,6-tetramethylpiperidine) is very potent for inhibition of SHP-77 growth in nude mice. When injected daily i.p. at 5 mg·kg1, M-570 gave 90% suppression of tumor growth. M-570 is more potent than the well-known anticancer drug cisPlatin (60% inhibition) or the recently developed SU5416 (40% inhibition) in this model. M-570 also showed activity against various other cancer cell lines in vitro (SCLC, non-SCLC, lung, prostate, colon, cervix) and inhibited growth of prostate cell line PC3 in nude mice. M-570 and related compounds evidently act in vivo through pathways other than BK receptors. These compounds have clinical potential for treatment of human lung and prostate cancers.Key words: bradykinin antagonists, cancer, inflammation, prostate cancer, small cell lung cancer.
Pharmacological characterisation of novel kinin B2 receptor ligands
Authors: Camarda V , Rizzi A , Calò G , Wirth K , Regoli D
Published: November 2002

Peptide and nonpeptide compounds have been shown to interact specifically with B2 receptors of three different species, namely human, rabbit, and pig. Peptide agonists and nonpeptide antagonists show marked differences in potencies and suggest the existence of B2 receptor subtypes. This conclusion is based on data obtained with the modified agonist peptide LF 150943 whose potency (pEC50 9.4) is at least 100-fold higher in rabbit than in humans (7.4) and pig (6.7). The same conclusion can be drawn from data obtained with antagonists that are more potent in humans (LF 160687, pA2 9.2) than in rabbit (8.7) and pig (8.2) or with antagonists (S 1567) that show the opposite potency order, being much weaker in humans (pA2 6.9) than in rabbit (7.6) and pig (9.4). Two other compounds (FR 173657 and FR 172357) show similar pharmacological spectra as S 1567 and differ from LF 160687.Key words: bradykinin, B2 receptor ligands, bioassay, isolated vessels.
Kinin B1 and B2 receptor mRNA expression in the hypothalamus of spontaneously hypertensive rats
Authors: Qadri F , Häuser W , Jöhren O , Dominiak P
Published: November 2002

The central hypertensive effects induced by bradykinin are known to be mediated via B2 receptors, which are present constitutively in the brain. B1 receptors are rapidly upregulated during inflammation, hyperalgesia, and experimental diabetes. The hypothalamus plays an important role in the regulation of cardiovascular homeostasis, and all components of kallikreinkinin system have been identified in this area. Therefore, we analyzed the mRNA expression of B1 and B2 receptors in the hypothalamus of spontaneously hypertensive rats (SHR) by RT-PCR. Male SHR were studied at three different ages corresponding to the three phases in the development of hypertension: (i) 34 (prehypertensive), (ii) 78 (onset of hypertension), and (iii) 1213 weeks (established hypertension) after birth, and compared with age-matched WistarKyoto (WKY) rats. At all ages tested, B2 receptor mRNA levels in the hypothalamus of SHR were higher than age-matched WKY rats (p < 0.001). However, the B1 receptor mRNA levels were higher at the established phase of hypertension only. We conclude that B1 and B2 receptor mRNA are differentially expressed in the hypothalamus of SHR and may play different roles in the pathogenesis of hypertension: upregulation of B2 receptor mRNA from early age may participate in the pathogenesis of hypertension, whereas an upregulation of B1 receptor mRNA in the established phase of hypertension may reflect an epiphenomenon in essential hypertension.Key words: kinin receptors, mRNA expression, hypothalamus, SHR, WKY.
Diabetes-induced changes in responsiveness of rat bladder and vas deferens to peptides in vitro: susceptibility to reversal by insulin
Authors: Cardozo A HM , Cabrini D A , Campos M M , Rae G A , Huidobro-Toro J P , Calixto J B
Published: November 2002

Changes in responsiveness of the vas deferens and urinary bladder to bradykinin (BK) receptor agonists (Tyr8-BK and des-Arg9-BK), substance P (SP), and endothelin-1 (ET-1) were assessed 8 weeks after streptozotocin (STZ)-induced diabetes. Preparations from control or STZ-treated (60 mg/kg i.p.) male rats were tested for contractile and neurogenic twitch potentiating (TP, in VD only) effects of all four agonists (1 nM to 0.3 or 3 µM). In diabetic VD, contractile effects of Tyr8-BK, des-Arg9-BK, and SP were enhanced, but ET-1 effects were unchanged. In contrast, TP by des-Arg9-BK was unaffected, that by Tyr8-BK was decreased, and those by SP and ET-1 were increased. In diabetic UB, only contractions to des-Arg9-BK and SP were enhanced. Following insulin replacement (human, 13 U/day s.c.), starting 1 week after STZ, TP induced by Tyr8-BK and des-Arg9-BK in VD were further inhibited, but all other changes in both preparations were reversed at least partially. Insulin treatment of nondiabetic rats, however, also affected VD (but not UB) responsiveness, such that contractions to Tyr8-BK and TP by ET-1 were increased, but TP by Tyr8-BK was decreased. Thus, STZ-induced type I diabetes causes important alterations in responsiveness of non-vascular smooth muscle tissues of the rat to BK, SP, and ET-1. Long term insulin replacement, at doses normalising glycaemia, effectively reversed most changes in VD or UB responsiveness, but it is unclear if this is truly due to blocking of STZ-induced changes, since the treatment also affected responsiveness of nondiabetic tissues.Key words: streptozotocin diabetic rats, insulin, kinins, B1 and B2 agonists, endothelin, substance P, rat vas deferens, urinary bladder.
Repeatability of sperm number across multiple matings in three cricket species, Gryllodes sigillatus, Gryllus veletis, and Gryllus texensis (Orthoptera: Gryllidae)
Authors: Schaus Jennifer M , Sakaluk Scott K
Published: November 2002

Although studies of various taxa have shown that males can alter the number of sperm in their ejaculates according to the risk of sperm competition, few studies have examined the extent to which the number of sperm transferred by males across multiple matings is repeatable. We assess the within-male and between-male components of variation in sperm number by counting the sperm in multiple ejaculates of males of three cricket species and determining the repeatability of sperm number. Sperm number was highly repeatable across multiple matings in all three species, leaving open the possibility that variation in sperm number is based, in part, on heritable genetic variation.
Home range and movements of a wood turtle (Clemmys insculpta) population at the northern limit of its range
Authors: Arvisais Martin , Bourgeois J -C , Lévesque E , Daigle C , Masse D , Jutras J
Published: November 2002

We studied the home ranges and seasonal movements of 20 wood turtles (Clemmys insculpta) living near the northern limit of their distribution in the Mauricie region, Quebec, Canada. We found average home-range areas of 28.3 ha. Wood turtles showed site fidelity; there was an average overlap of 60.7% in their home ranges, and 88.8% of the home-range centroids were not significantly different for the 2 years of the study. The home ranges were larger than those reported from studies in more southerly locations, leading us to hypothesize larger home-range territories with increasing latitude. Our analyses indicate that turtle movements could be grouped into four distinct activity periods during the active season: the prenesting, nesting, postnesting, and prehibernation periods. We found that wood turtles were closely associated with streams. Based on the importance of this habitat for the species, we suggest the establishment of protected buffer strips along streams used by wood turtles.
Energetic consequences of sex-related habitat segregation in wintering American kestrels (Falco sparverius)
Authors: Ardia Daniel R
Published: November 2002

Behavioural dominance can cause individuals to use less-preferred habitats, with potentially important life-history consequences. In the American kestrel, Falco sparverius, females exclude males from preferred open areas; I hypothesized that this sex-related habitat segregation leads to energetic consequences for males. I predicted that males would show decreased body condition over winter, while females would not, and that females would maintain larger net-energy surpluses than would males. Working in southeastern Pennsylvania, between 1991 and 1995, I conducted 150 behavioural observations and measured body condition of 235 wintering kestrels. Male kestrels maintained a lower body condition (residuals of a regression of mass vs. size) than did females and showed a decrease in mean body condition over winter, which females did not. I estimated that females had larger daily energy expenditures than did males (248 vs. 195 kJ per bird per day, ratio 1.27) but also had larger daily energy intakes (537 vs. 322 kJ/day, ratio 1.67). Females had larger net energy surpluses than did males (288 vs. 126 kJ/day, ratio 2.27), particularly when temperatures were <0°C. I conclude that differences in energetics are due in part to habitat differences and that males may suffer consequences by being forced to use less-preferred habitats.
To heat or to save time? Thermoregulation in the lizardZootoca vivipara(Squamata: Lacertidae) in different thermal environments along an altitudinal gradient
Authors: Gvoždík Lumír
Published: November 2002

Behavioural regulation of body temperature in thermally heterogeneous habitats requires different amounts of time that could otherwise be dedicated to foraging and social activities. In this study I examined how four populations of the lizard Zootoca vivipara along an altitudinal gradient (250-1450 m) adjust their thermal-physiology traits and thermoregulatory behaviour to compensate for increasing time costs of thermoregulation. I focused on variation in several physiological (set-point temperature, heating rate) and behavioural traits (microhabitat selection, basking frequency, extent of thermoregulation). To estimate potential time spent basking and foraging by lizards that were not employing any behavioural compensatory mechanism, I used a simple biophysical model of thermoregulation, including information about operative temperatures at the study sites, selected temperature range, and heating/cooling rates. Time costs of thermoregulation for each population were calculated as potential time spent basking relative to time spent foraging. Operative temperatures varied among study sites, resulting in different time costs of thermoregulation. Lizards at 1450 m should spend about 50% more time basking than those at 250 m. I found that the only mechanism which potentially compensated for the higher time costs incurred at high altitudes was a shift in the choice of basking sites. Lizards thermoregulated with similar accuracy and effectiveness over the 1200-m altitudinal range, indicating that there were no adjustments in the extent of thermoregulation. The observed basking frequencies of lizards were highly correlated with potential time spent basking without behavioural adjustments, suggesting a minor compensatory effect of thermoregulatory behaviour. Lizards responded to higher time costs of thermoregulation primarily by allocating different amounts of time to basking. These results suggest that Z. vivipara regulated body temperature at the expense of time that could be devoted to other activities.
Abundance and maturity of three species of parasitic anisakine nematodes (Pseudoterranova decipiens, Contracaecum osculatum, Anisakis simplex) occurring in Sable Island harbour seals (Phoca vitulina)
Authors: Stobo Wayne T , Fanning L Paul , Beck Brian , Fowler G Mark
Published: November 2002

Three species of anisakine nematodes (Pseudoterranova decipiens, Contracaecum osculatum, Anisakis simplex) co-occur in the stomachs of Sable Island harbour seals (Phoca vitulina). The sealworm, P. decipiens, was the commonest nematode in these seals. Anisakis simplex was found in much smaller numbers, none mature, indicating that the harbour seal is not a true final host to this parasite. Contracaecum osculatum was rare but half were mature. Pseudoterranova decipiens increased in abundance with size of the seal. An inverse relationship was observed between P. decipiens abundance and the age of seals of similar size, probably owing to changes in diet. Numbers of P. decipiens may have declined over the summer, coincident with an increase in the proportion of mature worms in the stomach. From similarities between the worm infections of grey seals (Halichoerus grypus) and harbour seals, we infer that A. simplex abundance may also exhibit a decline in abundance. Contracaecum osculatum was only encountered during the latter half of the year, suggesting an association with prey species of corresponding periodicity in their distribution. We estimate that the abundance of sealworm in harbour seals is about 2.5% of that carried by the grey seal population. This could imply that harbour seals represent an insignificant vector of the sealworm infecting commercial fish species in the Northwest Atlantic, provided density-dependent relationships exist between worm abundances in different host species.
A longitudinal study of senescence in a pinniped
Authors: Pistorius Pierre A , Bester Marthán N
Published: November 2002

To measure the prevalence of senescence in southern elephant seals (Mirounga leonina Linn.) at Marion Island, changes in adult-female survival and breeding probabilities with age were quantified. Markrecapture data that had been collected over a 17-year period were analysed using recently developed software to obtain likelihood estimates of survival and capture probabilities. With recapture effort constant over the study period, capture probabilities during the breeding seasons were used as indices of breeding probabilities. Longevity in the population was assessed from the resighting of tagged and hence known-age individuals. Less than a 1% difference between prime-age survival and post prime age survival was found over 8 cohorts of marked females. In addition, no reduction in survival of very old individuals was detected, suggesting the absence of senescence in terms of reduced survival in southern elephant seals. No evidence of reproductive senescence in terms of reduced breeding probability with age was detected. Mortality throughout the population therefore resulted in no individuals surviving to the age where physiological decline would become a mortality agent or result in failure to breed. Five percent of female southern elephant seals survived to age 10 and 0.5% to age 17.
Food fights in house crickets, Acheta domesticus, and the effects of body size and hunger level
Authors: Nosil P
Published: November 2002

Animals often compete directly with conspecifics for food resources, and fighting success can be positively related to relative resource-holding power (RHP) and relative resource value (i.e., motivation to fight). Despite the ease of manipulating resource value during fights over food (by manipulating hunger levels), most studies have focused on male fighting in relation to gaining access to mates. In this study, pairwise contests over single food items were used to examine the effects of being the first to acquire a resource, relative body mass, relative body size (femur length), and relative level of food deprivation (i.e., hunger) on competitive feeding ability in male and female house crickets, Acheta domesticus. Only when the food pellet was movable did acquiring the resource first improve fighting success. When the pellet was fastened to the test arena, increased relative hunger level and high relative body mass both increased the likelihood of a takeover. However, the effects of body mass disappeared when scaled to body size. When the attacker and defender were equally hungry, larger relative body size increased takeover success but, when the attacker was either more or less hungry, body size had little effect on the likelihood of a takeover. Thus fight outcomes were dependent on an interaction between RHP and motivational asymmetries and on whether the resource was movable or stationary. Contest duration was not related to the magnitude of morphological differences between opponents, suggesting that assessment of fighting ability may be brief or nonexistent during time-limited animal contests over food items.
Ionoregulatory strategies and the role of urea in the Magadi tilapia (Alcolapia grahami)
Authors: Wood Chris M , Wilson Paul , Bergman Harold L , Bergman Annie N , Laurent Pierre , Otiang'a-Owiti George , Walsh Patrick J
Published: November 2002

The unique ureotelic tilapia Alcolapia grahami lives in the highly alkaline and saline waters of Lake Magadi, Kenya (pH ~10.0, alkalinity ~380 mmol·L1, Na+~350 mmol·L1, Cl~110 mmol·L1, osmolality ~580 mosmol·kg1). In 100% lake water, the Magadi tilapia maintained plasma Na+, Cl, and osmolality at levels typical of marine teleosts and drank the medium at 8.01 ± 1.29 mL·kg1·h1. Gill chloride cells were predominantly of the sea water type (recessed, with apical pits) but a few freshwater-type chloride cells (surficial, with flat apical exposure) were also present. Whole-body Na+and Clconcentrations were relatively high and exhibited larger relative changes in response to salinity transfers than did plasma ions. All fish succumbed upon acute transfer to 1% lake water, but tolerated acute transfer to 10% lake water well, and gradual long-term acclimation to both 10 and 1% lake water without change in plasma cortisol. Plasma osmolytes were here maintained at levels typical of freshwater teleosts. Curiously, drinking continued at the same rate in fish adapted to 1% lake water, but chloride cells were now exclusively of the freshwater type. Significant mortality and elevated cortisol occurred after acute transfer to 200% lake water. However, the fish survived well during gradual adaptation to 200% lake water, although plasma cortisol remained chronically elevated. Urea levels accounted for only 23% of internal osmolality in 100% lake water but responded to a greater extent than plasma ions during exposure to 10 and 200% lake water, decreasing by 2842% in the former and increasing by over 500% in the latter relative to simultaneous-control values. Urea thereby played a small but significant role (up to 8% of internal osmolality) in osmoregulation.
Survival of protected white-lipped peccaries in Costa Rica
Authors: Fuller Todd K , Carrillo Eduardo , Saenz Joel C
Published: November 2002

The conservation of remnant populations of white-lipped peccaries (Tayassu pecari) in Central America depends on understanding their demography, but few quantitative data exist. We report survival and cause-specific mortality of 25 female and 11 male radio-marked adult (>1.0 year old) white-lipped peccaries monitored during February 1995  February 2001 in Corcovado National Park, their largest stronghold in Costa Rica. Annual survival was lower for female (0.78; 95% CI = 0.680.88) than for male (0.94; 95% CI = 0.861.00) peccaries. Both sexes were poached and died in accidents but only females were killed by predators or died of unknown causes (but not poaching). In comparison with the demography of collared peccaries (Tayassu tajacu), the population of white-lipped peccaries in Corcovado National Park may be maintaining itself. Still, protected areas may need to be expanded and (or) more forcefully monitored to sustain white-lipped peccaries throughout their range if additional use by humans is likely to occur, especially given stochastic population processes and human population increases.
Temporal, population, and sexual variation in hematocrit of free-living desert tortoises: correlational tests of causal hypotheses
Authors: Peterson Charles C
Published: November 2002

Hematocrit (packed cell volume, PCV) varies seasonally in some vertebrates and often differs between the sexes and among conspecific populations. Such variation in PCV may reflect variation in nutritional health, requirements for oxygen transport (metabolic rate), or hydration. The relative importance of these influences was tested with serial measurements of PCV in two Mojave Desert populations of the desert tortoise (Gopherus agassizii) over two activity seasons, during a period with large seasonal differences in availability of food and water. Hematocrit varied widely (range = 1440, CV = 20%), reflecting differences between populations, between sexes, between years, and over time within years. Causal hypotheses were tested by correlating PCV with physiological indicators of nutritional health (blood urea nitrogen), oxygen requirements (field metabolic rate), and hydration (length-relative mass, water-influx rate, urine osmolality, plasma sodium, and plasma osmolality). Results indicated a dominant influence of dehydration-induced hemoconcentration during this extreme drought period, although all correlations were relatively weak. Circumstantial evidence is marshalled to suggest longer term effects of nutrition (at seasonal, yearly, and population levels of variation) and perhaps oxygen requirements (driving sexual dimorphism). All these simultaneous and sometimes opposing effects interact in complex ways to produce the patterns of variation observed, and these interactions render PCV a poor indicator of physiological state in desert tortoises.
Heritability and "evolvability" of meristic characters in a natural population ofGasterosteus aculeatus
Authors: Hermida M , Fernández C , Amaro R , Miguel E San
Published: November 2002

Phenotypic and genetic variabilities of nine meristic traits (in threespine stickleback, Gasterosteus aculeatus) were calculated for 33 full-sib families raised under controlled laboratory conditions and for 33 pairs caught in nature. Heritabilities were measured using three methods: regression (across environments, laboratorynature), full sib (laboratory), and minimum estimate (nature). Evolvabilities, as an alternative measure of genetic variability, were computed from the genetic coefficient of variation across environments, in the laboratory, and in nature. In general terms, phenotypic variability was smaller in laboratory-reared fish than in wild fish. Results applying both parameters (heritability and evolvability) suggest that in the natural environment, there is a relevant presence of additive genetic variability for lateral-plate number and, to a lesser extent, for lower gill rakers, as well as maternal effects on caudal and abdominal vertebrae and paternal effects on dorsal fin rays. Some of the meristic traits examined are bilateral. Heritabilities across environments and in the laboratory for fluctuating asymmetry values were calculated according to conventional methods and also employing method 2 of Falconer. Qualitatively, the results were almost the same using the two methods: most heritability values were around zero, even taking into account overall measures of fluctuating asymmetry.