bluuebunny/crossref_metadata_2025 huggingface dataset:
Average daily metabolic rate, reproduction and energy allocation during lactation in the Sundevall Jird Meriones crassus
Authors: Kam M. , Cohen‐Gross S. , Khokhlova I. S. , Degen A. A. , Geffen E.
Published: August 2003

Non‐reproducing Sundevall Jird (Meriones crassus) females (body mass = 84 g; n = 51), with a mean average daily metabolic rate (ADMR) of 88 kJ day−1, were divided into three groups: high (H), medium (M) and low (L) ADMR. It was hypothesized that ADMR is related to reproductive rate and predicted that the H group could support a higher reproductive rate than the L group. It was also hypothesized that allocation of energy differs with ADMR level and predicted that the H group would use mainly the reallocation of metabolizable energy to compensate for an increased energy demand for reproduction whereas the L group would increase their metabolizable energy intake markedly. To test the hypotheses, the females were mated and, in those that had litters (n = 32), changes in body mass and metabolizable energy intake were determined and milk production was estimated during 15 days of lactation. Litter size, offspring mass and growth rate were determined for pups.

Body mass of dams, litter size and body mass of young at birth were similar among ADMR groups. However, milk production was 42% higher and litter mass at 15 days was significantly greater in the H than in L group, supporting our first hypothesis. All females were in negative energy balance during lactation. Mobilization of body energy reserves increased with litter size but was similar among ADMR groups. In addition, the increase in metabolizable energy intake of lactating females above that of non‐reproducing females was similar among ADMR groups and therefore the second hypothesis was rejected.

ADMR was reduced by 23% during lactation and milk energy was only 30% of total metabolizable energy invested in milk production in all females. It is concluded that lactating M. crassus used a combination of reallocation of energy and increased metabolizable energy intake during lactation. The efficiency of offspring production did not differ among ADMR groups and therefore a high ADMR has an advantage when food is abundant, whereas a low ADMR has an advantage when food is sparse.
Observational and simulated evidence of ecological shifts within the soil nematode community of agroecosystems under conventional and organic farming
Authors: Mulder CH. , Zwart D. DE , Van Wijnen H. J. , Schouten A. J. , Breure A. M.
Published: August 2003

Soil sustainability implies a sufficient diversity and abundance of organisms to perform soil functions and to resist environmental stress. Previous studies have shown the importance of functional biodiversity for soil organisms.

Soil samples have been collected within the framework of a long‐term monitoring programme in the Netherlands. Nematological and microbiological techniques were combined to facilitate a more comprehensive understanding of possible below‐ground effects of land management.

A possible bias due to stochastic circumstances was investigated. The Mantel test showed that the diversity at species level is largely related to air temperature, but at genus level the effect of temperature disappears. No direct influence of rainfall on the soil biodiversity was found in our model.

To extrapolate our data to a national level, habitat–response relationships for soil organisms have been derived. Generalized linear models (GLMs) and Monte Carlo simulation allowed the estimation of the probability of occurrence at a given abundance for 95 nematode genera.

Our study describes the influence of abiotic conditions and land use intensity on the composition of nematode communities in grasslands on sand. The results obtained reveal a major influence of pH and livestock density on the diversity of the nematode community at both taxonomic levels as well as at different trophic levels (feeding habits). The presence and abundance of soil nematodes decrease with cattle pressure.

Functional diversity decreases with increasing management intensity. It is shown that the Shannon diversities of bacterial feeding nematodes and fungal feeding nematodes are strictly related to cattle pressure, whereas the bacterial biomass occurring under organic farming scores higher than in other farming systems.
Locomotor speeds of gravid lizards: placing ‘costs of reproduction’ within an ecological context
Authors: Shine R.
Published: August 2003

Mathematical models suggest that ‘costs of reproduction’ (decrements in an organism's probable future reproductive output due to investing in current reproduction) are major determinants of life‐history evolution.

Pregnancy decreases locomotor performance in many taxa, and could render reproducing females more vulnerable to predators. To evaluate the importance of this ‘cost of reproduction’, however, we need to know the magnitude of performance decrement induced by reproduction relative to that induced by other factors in the animal's biology.

Studies on adult female skinks (Lampropholis guichenoti) confirm that pregnancy significantly impairs maternal locomotion, but also show that factors such as a moderate decrease in body temperature, a large meal or loss of the tail reduced locomotor speeds even more than did pregnancy. Thus, reproductive state probably causes only a minor proportion of the total temporal variation in a female skink's locomotor ability.

In such a system, even a large effect of pregnancy on running speeds may not impose a significant selective pressure on reproductive investment.

Climate and foraging modes may affect the degree to which locomotor speeds are influenced by pregnancy vs. other factors, offering a potential explanation for the lower overall reproductive investment per clutch in tropical vs. temperate‐zone reptiles, and in lizards vs. snakes.
Nutrient resorption from senescing leaves of the clonal plant Linnaea borealis in relation to reproductive state and resource availability
Authors: Niva M. , Svensson B. M. , Karlsson P. S.
Published: August 2003

We tested the hypotheses that (i) reproductive ramets of Linnaea borealis L. (Caprifoliaceae) compensate for reproductive investments by enhanced resorption of nitrogen (N) and phosphorus (P) from leaves before abscission, and that (ii) resorption is decreased by increased soil nutrient availability. We also investigated (iii) the significance of resorption for ramet growth and nutrient pool sizes.

Leaves from reproductive, post‐reproductive and non‐reproductive ramets were used to investigate compensatory resorption of N and P. To study resorption responses to increased nutrient availability, slow‐release fertilizer was applied and differences between defoliated and shaded ramets were noted.

No compensation for reproductive investments via resorption from senescing leaves was detected. Resorption efficiency increased with increased nutrient availability for N, but showed no response for P. No effect of experimentally denied resorption was seen.

We propose that extensive physiological integration within clonal fragments of L. borealis buffers resource alterations in ramets associated with reproduction, fertilization and prevented resorption.

Our results show that the performance of a ramet of a physiologically well integrated plant is not governed by local conditions – ramets can exceed patch nutrient availability without reduced growth and nutrient status.
The effects of spatially heterogeneous nutrient supply on yield, intensity of competition and root placement patterns in Briza media and Festuca ovina
Authors: Day Kieron J. , John Elizabeth A. , Hutchings Michael J.
Published: August 2003

An experiment was carried out to determine whether the spatial pattern of soil nutrient distribution influences plant growth and root placement, and the intensity of competition between plants. Our hypotheses were that (i) growth would be greater for plants in heterogeneous than homogeneous conditions (ii) competitive intensity would be greater when nutrients were confined to a small proportion of the substrate volume than when uniformly distributed, and (iii) plants would selectively place roots in nutrient‐rich patches in heterogeneous conditions.

We grew plants of Briza media and Festuca ovina alone, or with an intra or interspecific competitor, in pots in which the same total supply of nutrients was distributed either homogeneously or heterogeneously. Nutrients in the heterogeneous treatment were confined to three soil cores occupying only 6·5% of the substrate volume.

Pattern of nutrient supply did not affect yield of plants grown alone. However, the reduction in target plant yield caused by competition was much greater in heterogeneous than homogeneous conditions (i.e. competitive intensity was greater in heterogeneous conditions).

Plants growing in heterogeneous conditions placed roots preferentially in the nutrient‐rich substrate patches. This may have been the cause of greater competitive intensity in heterogeneous conditions. It is speculated that soil‐based heterogeneity might exert an important influence on community structure and composition through its effects on competition.
Allocation of above‐ground growth is related to light in temperate deciduous saplings
Authors: King D. A.
Published: August 2003

Allocational shifts in response to light may be an important factor in allowing plants to survive in shade, while increasing their extension rates and competitive ability in sun. To investigate this response, the allocation of above‐ground growth between leaves, branches and stems was studied in saplings ofAcer pensylvanicumL. andCastenea dentata(Marsh.) Borkh. in the Appalachian mountains of western Virginia, USA. Measurements of current leaf biomass, current and past year leaf numbers and the growth ring widths of branches and stem were used to estimate biomass partitioning for saplings growing in locations ranging from forest understorey to large openings.

Both species showed higher leaf area per unit leaf biomass (SLA) and higher allocation of above‐ground growth to leaves in shade than in sun.

There were no differences between species in the slopes of the relationships of allocation and SLAvsestimated irradiance, but SLA was significantly greater inA. pensylvanicumthan inC. dentataat a given light level. Hence, somewhat lower production per unit leaf area is required to maintain the canopy inA. pensylvanicum, consistent with foresters’ ratings of greater shade tolerance for this species.

Greater foliar allocation in shade than sun has also been observed in broad‐leaved evergreen saplings, but generally not in seedlings. This difference is probably related to differences in size and age between seedlings and saplings. Young seedlings typically show exponential growth with no immediate foliar losses, while shaded saplings lie closer to the steady state where new leaves replace old ones with little additional stem growth.

Thus trees shift their allocation patterns in an acclimatory fashion, depending on their size and light environment, with the costs of replacing senesced leaves becoming of consequence as juveniles age.
Leaf attributes in the seasonally dry tropics: a comparison of four habitats in northern Australia
Authors: Prior L. D. , Eamus D. , Bowman D. M. J. S.
Published: August 2003

Patterns of leaf attributes were compared at regional and global scales in relation to the seasonal availability of water.

Light‐saturated assimilation rate (Amass), leaf mass per area (LMA), leaf density, thickness, life span, saturated water content, chlorophyll, nitrogen and phosphorus content were determined during the wet season for 21 tree species in four contrasting habitats in northern Australia. Rainfall in this area is extremely seasonal.

A
mass and foliar chlorophyll, N and P contents were positively correlated with each other, and were all negatively correlated with LMA, leaf thickness, density and life span.

Deciduous species had smaller LMA and leaf life span, and larger foliar N and P contents than did evergreen species.

The eight Myrtaceous species had smaller Amass, foliar chlorophyll, N and P contents, and larger LMA, leaf thickness and leaf life span than did the non‐Myrtaceous species.

Leaves from the closed canopy dry monsoon forest had significantly larger Amass, chlorophyll and P contents than did leaves from the three open canopy habitats (eucalypt open forest, mixed woodland and Melaleuca swamp). This reflected the relatively low proportions of evergreen and Myrtaceous species in the dry monsoon forest. There were also significant intraspecific differences among habitats.

Leaf thickness, density and LMA were lower than predicted from globally derived relationships with temperature and precipitation. Tropical seasonally dry biomes are under‐represented in such global analyses.
Condition dependence of pheromones and immune function in the grain beetle Tenebrio molitor
Authors: Rantala Markus J. , Kortet Raine , Kotiaho Janne S. , Vainikka Anssi , Suhonen Jukka
Published: August 2003

Pheromones are chemical signals that function not only as mate attractors, but may also relay important information to prospective mates. In order for the information to be reliable, the signal must be costly to produce and this is likely to result in condition dependent expression of the signal.

We present results from two experiments on the grain beetle Tenebrio molitor examining phenotypic condition dependence of pheromones and patterns of female preference for pheromones. We also analysed condition dependence of two measures of immunocompetence: encapsulation response and phenoloxidase activity.

By manipulating the nutritional condition of the males we found that the attractiveness of the male pheromones to virgin females was condition‐dependent, indicating that the production of the pheromones is affected by the condition of the male. We also found that the phenoloxidase activity of the males was affected by the nutritional condition of the male but that encapsulation rate was not.

Our results show that pheromones are condition‐dependent signals, the quantity of which females use in their mate choice.
How feather colour reflects its carotenoid content
Authors: Saks Lauri , McGraw Kevin , Hõrak Peeter
Published: August 2003

Many birds sequester carotenoid pigments in colourful patches of feathers to advertise or compete for mates. Because carotenoids can be scarce in nature and serve valuable physiological functions, only the highest‐quality individuals are thought to acquire or allocate more pigments for use in sexual displays.

A critical but rarely tested assumption of carotenoid‐based signals is that the colour of pigmented feather patches directly reveals the total amount of carotenoids contained within them.

We studied the relationship between carotenoid‐based coloration (hue, chroma and brightness) and the pigment content of tail feathers in wild‐caught and captive male greenfinches (Carduelis chloris[Linnaeus]). Greenfinches incorporate two main carotenoids − canary xanthophylls A and B − into feathers to develop yellow patches of colour in their tail.

Variation in feather carotenoid content explained 32–51% of variation in chroma and hue of the yellow parts of tail feathers, while feather brightness was not significantly related to carotenoid concentration. Hence, chroma and hue appear good candidates to indicate feather carotenoid content.

Birds with the most colourful feathers deposited significantly more of both canary xanthophylls into plumage. Thus, there does not appear to be a specific biochemical strategy for becoming colourful in greenfinches; males instead follow the general decision rule to deposit as many xanthophylls as possible into feathers to become yellow.
Leaf life span differs from retention time of biomass and nutrients in the crowns of evergreen species
Authors: Mediavilla S. , Escudero A.
Published: August 2003

A long leaf life span has been interpreted as an adaptation to low nutrient availability. It is commonly assumed that a long leaf life span permits a longer utilization of nutrients in the leaf biomass and that this contributes to improving nutrient use efficiency. However, a long leaf life span is also associated with other leaf traits that reduce instantaneous productivity, which might reduce the growth rate of the leaf biomass and shorten the functional life of the leaf.

We studied the relationships between leaf life span and the retention time of biomass and nutrient pools in several woody species with different leaf life spans. We measured the monthly variations in the total number of leaves per annual shoot, mass per leaf, and N and P contents per leaf. With these data, the leaf life span and the mean residence time (MRT) of leaf biomass and nutrient pools were estimated.

The increase in the total number of leaves was fast in all species studied at the start of the growth season. In contrast, in evergreen species mass per leaf and total N and P contents per leaf increased gradually after the first year of life of the leaves, and the maximum mass and nutrient contents per leaf were attained only towards the end of the lifetime of the leaves.

Owing to the delay in the development of mass and nutrient pools with respect to leaf number dynamics, in evergreen species leaf life span was longer than the MRT of leaf biomass and nutrient pools because part of the leaf biomass and nutrient pool remained in the crown for a shorter time than the mean duration of the individual leaves.

The differences between leaf life span and the MRT of the biomass and nutrients increased with leaf life span. The slow growth of evergreen leaves therefore contributes to reduce the adaptive value of a long leaf life span as a mechanism to increase the duration of the photosynthetic machinery.
Exogenous jasmonic acid mimics herbivore‐induced systemic increase in cell wall bound peroxidase activity and reduction in leaf expansion
Authors: Moore Jason P. , Paul Nigel D. , Whittaker John B. , Taylor Jane E.
Published: August 2003

Jasmonic acid (JA), a ubiquitous regulator of the wound response in plants, is part of a long distance defence signalling pathway and when applied exogenously induces several defence related responses in many species including the activation of proteinase inhibitor (PIN) proteins and defence‐related metabolites.

There is evidence for an induced systemic resistance mechanism linking increased cell wall peroxidase activity with reductions in leaf expansion rates in Rumex obtusifolius, following limited grazing by the chrysomelid beetle Gastrophysa viridula. We hypothesised that herbivory induces strengthening of cell walls in distal, non‐damaged tissue through increases in peroxidase activity and that this mechanism was mediated systemically by JA.

JA was applied to the fully expanded fourth leaf of R. obtusifolius and expansion of leaf 8 was measured over 19 days. Treatment with exogenous JA induced a temporary reduction in the expansion rate of leaf 8 beginning 6 days after treatment. This reduction continued until day 7 and reduced final leaf areas in treated plants by approximately 20%.

Final epidermal cell areas in leaf 8 were reduced by approximately 25%, while epidermal cell numbers remained unchanged.

Cell wall bound peroxidase activity was measured in leaf 8 over a 6‐day period following application of JA to leaf 4. Activity increased approximately 9‐fold 2 days after treatment, before returning to control activities on day 3.

Treatment of leaf 4 with JA reduced the gregariousness of G. viridula larvae on the fully expanded leaf 8.

We postulate that JA acts as a signalling molecule in a long‐distance pathway responsible for inducing resistance to future attack through increases in cell wall bound peroxidase activity leading to cell wall toughening, while incurring a potential ecological cost in the form of reductions in subsequent leaf expansion.
Interpretation of tests for nut allergy in one thousand patients, in relation to allergy or tolerance
Authors: Clark A. T. , Ewan P. W.
Published: August 2003

Background Peanut and tree nut allergy are common, increasing in prevalence and the commonest food cause of anaphylaxis. In the USA, 7.8% are sensitized (have nut‐specific IgE), but not all those sensitized are allergic. Lack of data makes interpretation of tests for nut‐specific IgE difficult.

Objectives This is the first study to investigate the clinical significance of test results for peanut and tree nut allergy in allergic or tolerant patients. Findings are related to the severity of the allergy.

Method An observational study of 1000 children and adults allergic to at least one nut. History of reactions (severity graded) or tolerance to up to five nuts was obtained and skin prick test (SPT)/serum‐specific IgE (CAP) performed.

Results There was no correlation between SPT size and graded severity of worst reaction for all nuts combined or for peanut, hazelnut, almond and walnut. For CAP, there was no correlation for all nuts. Where patients tolerated a nut, 43% had positive SPT of 3–7 mm and 3% ≥ 8 mm. For CAP, 35% were positive (0.35–14.99 kU/L) and 5% ≥ 15 kU/L. In SPT range 3–7 mm, 54% were allergic and 46% were tolerant. There was poor concordance between SPT and CAP (66%). Of patients with a clear nut‐allergic history, only 0.5% had negative SPT, but 22% negative CAP.

Conclusions Magnitude of SPT or CAP does not predict clinical severity, with no difference between minor urticaria and anaphylaxis. SPT is more reliable than CAP in confirming allergy. Forty‐six per cent of those tolerant to a nut have positive tests ≥ 3 mm (sensitized but not allergic). One cannot predict clinical reactivity from results in a wide ‘grey area’ of SPT 3–7 mm; 22% of negative CAPs are falsely reassuring and 40% of positive CAPs are misleading. This emphasizes the importance of the history. Understanding this is essential for accurate diagnosis. Patients with SPT ≥ 8 mm and CAP ≥ 15 kU/L were rarely tolerant so these levels are almost always (in ≥ 95%) diagnostic.
Sleep Loss Reduces Diurnal Rhythm Amplitude of Leptin in Healthy Men
Authors: Mullington J. M. , Chan J. L. , Van Dongen H. P. A. , Szuba M. P. , Samaras J. , Price N. J. , Meier‐Ewert H. K. , Dinges D. F. , Mantzoros C. S.
Published: August 2003

The aim of the current study was to investigate the effects of sleep loss on the diurnal rhythm of circulating leptin levels. An indwelling forearm catheter was used to sample blood at 90‐min intervals for a total of 120 h, which included 88 h of sustained sleeplessness, in 10 healthy men. The diurnal amplitude of leptin was reduced during total sleep deprivation and returned toward normal during the period of recovery sleep. This finding provides evidence that sleep influences the nocturnal leptin profile, and may have implications for the understanding of the role of sleep in metabolic regulation and the aetiologies of obesity and the night eating syndrome.
Immunocytochemical Detection of Progesterone Receptor in the Female Rabbit Forebrain: Distribution and Regulation By Oestradiol and Progesterone
Authors: Caba M. , Rovirosa M. J. , Beyer C. , González‐Mariscal G.
Published: August 2003

There is no information on the neuroanatomical distribution of the progesterone receptor (PR) in the rabbit. Therefore, we mapped the distribution of PR‐immunoreactive cells in the forebrain of ovariectomized female rabbits. Vehicle‐injected ovariectomized rabbits showed PR‐immunoreactive cells only in the infundibular nucleus (IN) and nucleus X (lateral to the ventromedial hypothalamic nucleus). The injection of oestradiol benzoate (EB; 5 µg/day for 5 days) increased the number of PR‐immunoreactive cells in the IN and in three nuclei of the preoptic region (periventricular, medial, and principal). Abundant PR were also found in the paraventricular nucleus and nucleus X. Administration of progesterone (10 mg/day) for 3 days to EB‐treated rabbits (a treatment that induces digging behaviour for the maternal nest and suppresses sexual receptivity and scent‐marking) eliminated PR‐immunoreactivity from all brain areas analysed except the IN. Thus, one‐third of the number of cells seen in the ovariectomized + EB condition persisted in this region despite progesterone injections. Withdrawal of progesterone (and continuation of EB) for 5 (but not for 2) days (in a schedule similar to the one that induces straw‐carrying and hair‐pulling for the maternal nest) increased the number of PR‐immunoreactive cells in all regions analysed. These results show that restricted regions of the female rabbit forebrain express abundant PR which are either: (i) up‐regulated by oestradiol and down‐regulated by progesterone; (ii) oestradiol‐insensitive and down‐regulated by progesterone; or (iii) insensitive to both oestradiol and progesterone.
Androgen 5‐Alpha‐Reductase Type 2 is Highly Expressed and Active in Rat Spinal Cord Motor Neurones
Authors: Pozzi P. , Bendotti C. , Simeoni S. , Piccioni F. , Guerini V. , Marron T. U. , Martini L. , Poletti A.
Published: August 2003

Spinal cord motoneurones express high levels of androgen receptor. However, in responsive tissue, the effects of testosterone is often mediated by the more potent androgenic derivative 5‐alpha‐dihydrotestosterone (DHT). This compound is formed in androgen target cells by the enzyme 5‐alpha‐reductase. Two isoforms of the 5‐alpha‐reductase, with limited degree of homology, have been cloned, type 1 and type 2. The low affinity‐constitutive type 1 isoenzyme is widely distributed in the body; the high affinity‐androgen regulated 5‐alpha‐reductase type 2 is confined to androgen‐dependent structures and shows a peculiar pH optimum at acidic values. We have previously shown that high levels of 5‐alpha‐reductase activity are detectable in rat spinal cord. Here, using reverse transcriptase‐polymerase chain reaction, we show that both isoforms are expressed in the whole spinal cord of the rat. The enzymatic pH optimum measured in immortalized spinal cord motoneurones (NSC34) is typical of the type 2 isoenzyme. Using in situ hybridization technique, we found that 5‐alpha‐reductase type 2 is confined to the motoneuronal cells of the anterior horns of the rat spinal cord, the cells that also are known to express high levels of androgen receptor. Because of the close association of androgen receptor and 5‐alpha alpha‐reductase type 2, motoneuronal cells should be considered as target cells for androgens.
Impaired Somatodendritic Responses to Pituitary Adenylate Cyclase‐Activating Polypeptide (PACAP) of Supraoptic Neurones in PACAP type I ‐Receptor Deficient Mice
Authors: Jamen F. , Alonso G. , Shibuya I. , Widmer H. , Vacher C.‐M. , Calas A. , Bockaert J. , Brabet P. , Dayanithi G.
Published: August 2003

The role of pituitary adenylate cyclase‐activating polypeptide (PACAP) type I receptor (PAC1 receptor) in regulating hypothalamic supraoptic neurones was investigated using PAC1 receptor‐deficient male mice (PAC1−/−). The effects of PACAP on [Ca2+]i were investigated in freshly dissociated supraoptic neurones and on the somatodendritic release of vasopressin and oxytocin, examined on intact supraoptic nuclei. In supraoptic neurones from wild‐type mice (PAC1+/+), 100 nm PACAP induced an increase in [Ca2+]i and release of vasopressin and oxytocin, whereas in heterozygous (PAC1+/−) and null‐mutant mice (PAC1−/−), PACAP was much less effective. PACAP had no effect on these two parameters when applied to isolated neurohypophysial nerve terminals of PAC1+/+ and PAC1−/− mice, and rats. In conclusion, the PAC1 receptor is solely responsible for the PACAP‐induced [Ca2+]i signalling and secretion of vasopressin and oxytocin in the somatodendritic region of supraoptic neurones.
Leptin‐Target Neurones of the Rat Hypothalamus Express Somatostatin Receptors
Authors: Stepanyan Z. , Kocharyan A. , Pyrski M. , Hübschle T. , Watson A. M. D. , Schulz S. , Meyerhof W.
Published: August 2003

Hypothalamic leptinoceptive neurones can be visualized by histochemical demonstration of leptin‐induced nuclear translocation of the signalling molecule STAT3. We investigated the relationship of the leptinoceptive neurones to the somatostatin signalling system. With double‐labelling immunohistochemistry, we studied the colocalization of leptin‐activated transcription factor, STAT3, with somatostatin receptor subtypes, sst1, sst2A, sst2B, sst3 and sst4, or the neuropeptide itself, in the rat hypothalamus. Immunoreactivity for all the entities was widely distributed throughout the entire hypothalamus. Despite the wide distribution, only few cases of colocalization of somatostatin with leptin‐activated STAT3 were detected in the paraventricular, arcuate and dorsomedial nuclei. A moderate to high degree of colocalization of nuclear STAT3 and all investigated subtypes of somatostatin receptors was found in the lateral and dorsal hypothalamic areas and in the dorsomedial hypothalamic nucleus. Immunoreactivity for sst1, sst2B and sst4 was present in STAT3‐containing nuclei of the paraventricular, periventricular, arcuate and ventromedial hypothalamic neurones, as well as in the retrochiasmatic and posterior hypothalamic areas. Despite the wide distribution of sst2A in the rat hypothalamus, few events of colocalization with leptin‐activated STAT3 were observed in the dorsomedial nucleus and in the lateral and dorsal hypothalamic areas only. Many leptin‐responsive neurones of the dorsal, lateral, periarcuate, perifornical and posterior hypothalamic areas, as well as in the ventromedial and dorsomedial hypothalamic nuclei, displayed sst3 immunoreactivity at their neuronal cilia. These results provide strong anatomical evidence for the direct interaction of leptin and the somatostatin systems in neuroendocrine control loops such as the energy homeostasis, growth or stress response.
Responses of Cells in the Rat Suprachiasmatic Nucleus In Vivo to Stimulation of Afferent Pathways are Different at Different Times of the Light/Dark Cycle
Authors: Saeb‐Parsy K. , Dyball R. E. J.
Published: August 2003

Conventional extracellular recordings were made from single cells in the suprachiasmatic nucleus (SCN) region of the anaesthetized rat. Each cell was tested for its response to stimulation at three sites; the contralateral optic nerve, the ipsilateral supraoptic nucleus (SON) or the ipsilateral arcuate nucleus (ARC) to determine whether the behaviour of the synapses in the SCN was different at different times. Responses to stimulation were tested once each hour and assessed by creating peristimulus time histograms. Excitatory, inhibitory or complex (consisting of more than one component) responses were seen. The responses of some cells that were recorded for several hours changed with time. Changes were seen in the responses of SCN cells to stimulation of the ARC (31/91 cells) and the SON (26/90 cells) regions, but only rarely to stimulation of the optic nerve (2/72 cells). Such differences in proportion are unlikely to have occurred by chance (P < 0.001; chi‐square test). Changes seen included the appearance of both excitatory and inhibitory responses in cells that were initially unresponsive. In some cells, one component of a complex response remained constant while another component changed with time. When the cells in the SCN were treated as a group, the proportion of excitatory, inhibitory or complex responses to ARC stimulation did not remain constant throughout the light/dark cycle (P = 0.014; chi‐square test). The proportion of excitatory, inhibitory or complex responses to SON and optic nerve stimulation showed no significant variation with the light/dark cycle. If a change in response can be interpreted as a change in the behaviour of a neural connection, the results imply that some of the projections to the SCN from within the hypothalamus change at different times of the light/dark cycle, whereas no change could be seen in the input from the optic nerve. Thus, some of the connections of the SCN appear not to be hard wired, but change rapidly with time.
Evaluation of the clinical and allergen specific serum immunoglobulin E responses to oral challenge with cornstarch, corn, soy and a soy hydrolysate diet in dogs with spontaneous food allergy
Authors: Jackson H. A. , Jackson M. W. , Coblentz L. , Hammerberg B.
Published: August 2003

Abstract Fourteen dogs with known clinical hypersensitivity to soy and corn were maintained on a limited antigen duck and rice diet until cutaneous manifestations of pruritus were minimal (78 days). Sequential oral challenges with cornstarch, corn and soy were then performed. Subsequently, the dogs were fed a diet containing hydrolysed soy protein and cornstarch. Throughout the study period the dogs were examined for cutaneous manifestations of pruritus and, additionally, serum was collected for measurement of allergen‐specific and total immunoglobulin (Ig)E concentrations. Intradermal testing with food antigens was performed prior to entry into the study and after 83 days. A statistically significant clinical improvement was measured between days 0 and 83. Significant pruritus was induced after oral challenge with cornstarch, corn and soy (P = 0.04, 0.002, 0.01, respectively) but not with the hydrolysed diet (P = 0.5). The positive predictive value of the skin test for soy and corn allergy was reduced after feeding a soy and corn free diet. Although increases in soy and corn‐specific serum IgE concentrations were measured in individual dogs post challenge they were not statistically significant and could not be used to predict clinical hypersensitivity.
Efficacy of milbemycin oxime in the treatment of canine generalized demodicosis: a retrospective study of 99 dogs (1995–2000)
Authors: Holm Birgit R.
Published: August 2003

Abstract Ninety‐nine dogs diagnosed with generalized demodicosis were treated with milbemycin oxime. Cases diagnosed before two years of age were classified as juvenile‐onset (53%) and those diagnosed after two years of age as adult‐onset (47%). Dogs were considered cleared of mites when none could be demonstrated in scrapings and cured if no relapse was seen for 12 months. Eighty‐five per cent (84/99) were cured with milbemycin oxime used for 1–6 months (mean 2.3 months) at a dosage of 0.5–1.6 mg kg−1body weight (mean 0.75 mg kg−1). No significant difference in dosage or treatment time was seen between juvenile and adult cases. Chance of cure was significantly better in young animals (cured cases mean age 2.97 years) than in older animals (not cured cases mean age 8.02 years). Start of treatment early in the course of disease gave a significantly better chance of cure. Cases with severe pododemodicosis had less chance of a cure (9/11 not cured).
Hereditary nasal parakeratosis in Labrador retrievers: 11 new cases and a retrospective study on the presence of accumulations of serum (‘serum lakes’) in the epidermis of parakeratotic dermatoses and inflamed nasal plana of dogs
Authors: Peters Jeanine , Scott Danny W. , Erb Hollis N. , Miller William H.
Published: August 2003

Abstract  We report 11 new cases of hereditary nasal parakeratosis in Labrador retrievers. The disease was first observed when the dogs were 6 months to 2 years of age, and affected dogs of either sex and all coat colours. Hyperkeratosis and depigmentation were confined to the nasal planum, and affected dogs were otherwise healthy. The principal histological findings in biopsy specimens were marked diffuse parakeratotic hyperkeratosis, multiple intracorneal serum lakes and superficial interstitial‐to‐interface lymphoplasmacytic dermatitis. Topical applications of propylene glycol in water or white petrolatum were often effective for treatment of the dermatosis. However, continued applications were required to maintain a beneficial response. A retrospective histological study of parakeratotic inflammatory diseases of canine haired skin and inflammatory diseases of the canine nasal planum was performed. The degree of parakeratotic hyperkeratosis and the number and size of intracorneal serum lakes were evaluated. The degree of parakeratotic hyperkeratosis was greater in hereditary nasal parakeratosis specimens than that seen in discoid lupus erythematosus and Malassezia dermatitis. There were more serum lakes in hereditary nasal parakeratosis specimens than in specimens from dogs with discoid lupus erythematosus, Malassezia dermatitis, primary seborrheic dermatitis or zinc‐responsive dermatosis. Significant differences in sizes of serum lakes (if present) were not seen.
Sp1 acts as a repressor of the human adenine nucleotide translocase‐2 (ANT2) promoter
Authors: Zaid Ahmed , Hodny Zdenek , Li Ronggui , Nelson B. Dean
Published: August 2003

The human adenine nucleotide translocator‐2 promoter is activated by adjacent Sp1 activation elements centered at nucleotides −79 and −68 (Abox and Bbox, respectively), and is repressed by Sp1 bound to a GC element (Cbox) that lies adjacent to transcription start. Here, we address the mechanism of this unique Sp1‐mediated repression using transfected Drosophila SL2 and mammalian cell lines. We show that repression is not due to steric interference with assembly of the transcription machinery, as Sp1 bound to the Cbox can, under certain conditions, activate the promoter. Furthermore, ectopic expression of Sp1 deletion mutants in SL2 cells demonstrates that both the Sp1‐mediated repression and activation require the D transactivation domain of Sp1 bound to the Cbox. In addition, repression of ABbox‐mediated activation is eliminated by separating the Abox and Bbox. Thus, for Cbox‐bound Sp1 to repress, Sp1 must be precisely positioned at the region of the ABboxes. Together, these data suggest that the D transactivation domain mediates interactions by Sp1 complexes on separate GC elements that results in repression of the activating Sp1 species.
pH and kinetic isotope effects in d‐amino acid oxidase catalysis.
Authors: Harris Christopher M. , Pollegioni Loredano , Ghisla Sandro
Published: August 2003

The effects of pH, solvent isotope, and primary isotope replacement on substrate dehydrogenation by Rhodotorula gracilisd‐amino acid oxidase were investigated. The rate constant for enzyme‐FAD reduction by d‐alanine increases ≈ fourfold with pH, reflecting apparent pKa values of ≈ 6 and ≈ 8, and reaches plateaus at high and low pH. Such profiles are observed in all presteady‐state and steady‐state kinetic experiments, using both d‐alanine and d‐asparagine as substrates, and are inconsistent with the operation of a base essential to catalysis. A solvent deuterium isotope effect of 3.1 ± 1.1 is observed on the reaction with d‐alanine at pH 6; it decreases to 1.2 ± 0.2 at pH 10. The primary substrate isotope effect on the reduction rate with [2‐D]d‐alanine is 9.1 ± 1.5 at low and 2.3 ± 0.3 at high pH. At pH 6.0, the solvent isotope effect is 2.9 ± 0.8 with [2‐D]d‐alanine, and the primary isotope effect is 8.4 ± 2.4 in D2O. Thus, primary and solvent kinetic isotope effects (KIEs) are independent of the presence of the other isotope, i.e. the ‘double’ kinetic isotope effect is the product of the individual KIEs, consistent with a transition state in which rupture of the two bonds of the substrate to hydrogen is concerted. These results support a hydride transfer mechanism for the dehydrogenation reaction in d‐amino acid oxidase and argue against the occurrence of any intermediates in the process. A pKa,app of ≈ 8 is interpreted to arise from the microscopic ionization of the substrate amino acid α‐amino group, but also includes contributions from kinetic parameters.
Identification of genes expressed in response to light stress in leaves of Arabidopsis thaliana using RNA differential display
Authors: Dunaeva Marina , Adamska Iwona
Published: August 2003

The plant cell responds to light stress by the expression of genes encoding specific stress proteins with possible protective functions. Five genes, the mRNA levels of which increased drastically in response to light stress in mature green leaves of Arabidopsis thaliana were identified and isolated by the differential display technique. These genes were designated Lsr1–Lsr5 (light stress‐regulated). Northern blot analysis demonstrated that the transcript level of Lsr1–Lsr5 increased 4‐ to 17‐fold under light stress conditions as compared with leaves incubated at low intensity light. Further analysis of the Lsr1–Lsr5 transcript level under cold stress, heat shock, wounding, desiccation, salt stress, oxidative stress and UV‐A irradiation showed that the expression of all five genes was triggered by more than one stress factor. Thus, it was expected that isolated genes encode proteins involved in general stress responses. Homology searches revealed that all of the isolated cDNAs were represented in the GenBank in genomic DNAs and expressed sequence tag (EST) cDNA clones. The Lsr1–Lsr4 genes encoded cytoplasmic proteins with assigned identities, such as ERD15 (early responsive to dehydration), ACT2 (actin 2), LEA14 (late embryogenesis abundant) and MT1a (metallothionein class 1a), respectively. Light stress had not yet been reported to induce or enhance the expression of these genes. The Lsr5 clone encoded a novel protein with high similarity to β‐1,3‐galactosyltransferases from human and primates predicted to be located in the Golgi body. Three ORFs homologous to the Lsr5 gene were found on chromosome I and IV of Arabidopsis indicating that a multigene family of these proteins exists in plants. The possible role of Lsr gene products in light stress defences is discussed.
Characterization of indolinones which preferentially inhibit VEGF‐C‐ and VEGF‐D‐induced activation of VEGFR‐3 rather than VEGFR‐2
Authors: Kirkin Vladimir , Mazitschek Ralph , Krishnan Jaya , Steffen Anja , Waltenberger Johannes , Pepper Michael S. , Giannis Athanassios , Sleeman Jonathan P.
Published: August 2003

VEGF‐C and VEGF‐D are lymphangiogenic factors that bind to and activate VEGFR‐3, a fms‐like tyrosine kinase receptor whose expression is limited almost exclusively to lymphatic endothelium in the adult. Processed forms of VEGF‐C and VEGF‐D can also activate VEGFR‐2, a key player in the regulation of angiogenesis. There is increasing evidence to show that these receptor–ligand interactions play a pivotal role in a number of pathological situations. Inhibition of receptor activation by VEGF‐C and VEGF‐D could therefore be pharmaceutically useful. Furthermore, to understand the different roles of VEGF‐C, VEGF‐D, VEGFR‐2 and VEGFR‐3 in pathological situations it will be necessary to dissect the complex interactions of these ligands and their receptors. To facilitate such studies we cloned, sequenced and characterized the expression of rat VEGF‐C and VEGF‐D. We showed that Cys152→Ser mutants of processed rat VEGF‐C can activate VEGFR‐3 but not VEGFR‐2, while the corresponding mutation in rat VEGF‐D inhibits its ability to activate both VEGFR‐2 and VEGFR‐3. We also synthesized and characterized indolinones that differentially block VEGF‐C‐ and VEGF‐D‐induced VEGFR‐3 kinase activity compared to that of VEGFR‐2. These tools should be useful in analysing the different activities and roles of VEGF‐C, VEGF‐D and their ligands, and in blocking VEGFR‐3‐mediated lymphangiogenesis.
A novel two‐protein component flavoprotein hydroxylase
Authors: Chaiyen Pimchai , Suadee Chutintorn , Wilairat Prapon
Published: August 2003

p‐Hydroxyphenylacetate (HPA) hydroxylase (HPAH) was purified from Acinetobacter baumannii and shown to be a two‐protein component enzyme. The small component (C1) is the reductase enzyme with a subunit molecular mass of 32 kDa. C1 alone catalyses HPA‐stimulated NADH oxidation without hydroxylation of HPA. C1 is a flavoprotein with FMN as a native cofactor but can also bind to FAD. The large component (C2) is the hydroxylase component that hydroxylates HPA in the presence of C1. C2 is a tetrameric enzyme with a subunit molecular mass of 50 kDa and apparently contains no redox centre. FMN, FAD, or riboflavin could be used as coenzymes for hydroxylase activity with FMN showing the highest activity. Our data demonstrated that C2 alone was capable of utilizing reduced FMN to form the product 3,4‐dihydroxyphenylacetate. Mixing reduced flavin with C2 also resulted in the formation of a flavin intermediate that resembled a C(4a)‐substituted flavin species indicating that the reaction mechanism of the enzyme proceeded via C(4a)‐substituted flavin intermediates. Based on the available evidence, we conclude that the reaction mechanism of HPAH from A. baumannii is similar to that of bacterial luciferase. The enzyme uses a luciferase‐like mechanism and reduced flavin (FMNH2, FADH2, or reduced riboflavin) to catalyse the hydroxylation of aromatic compounds, which are usually catalysed by FAD‐associated aromatic hydroxylases.
Thermodynamic and kinetic analysis of porphyrin binding to Trichosanthes cucumerina seed lectin
Authors: Kenoth Roopa , Raghunath Reddy D. , Maiya Bhaskar G. , Swamy Musti J.
Published: August 2003

The interaction of several metallo‐porphyrins with the galactose‐specific lectin from Trichosanthes cucumeirna (TCSL) has been investigated. Difference absorption spectroscopy revealed that significant changes occur in the Soret band region of the porphyrins upon binding to TCSL and these changes have been monitored to obtain association constants (Ka) and stoichiometry of binding (n). The dimeric lectin binds two porphyrin molecules and the presence of the specific saccharide lactose did not affect porphyrin binding significantly, indicating that the sugar and the porphyrin bind at different sites. The Ka values obtained for the binding of different porphyrins with TCSL at 25 °C were in the range of 2 × 103−5 × 105 m−1. Association constants for meso‐tetra(4‐sulphonatophenyl)porphyrinato copper(II) (CuTPPS), a porphyrin bearing four negative charges and meso‐tetra(4‐methylpyridinium)porphyrinato copper(II) (CuTMPyP), a porphyrin with four positive charges, were determined at several temperatures; from the temperature dependence of the association constants, the thermodynamic parameters change in enthalpy (ΔH°) and change in entropy (ΔS°) associated with the binding process were estimated. The thermodynamic data indicate that porphyrin binding to TCSL is driven largely by a favourable entropic contribution; the enthalpic contribution is very small, suggesting that the binding process is governed primarily by hydrophobic forces. Stopped‐flow spectroscopic measurements show that binding of CuTMPyP to TCSL takes place by a single‐step process and at 20 °C, the association and dissociation rate constants were 1.89 × 104 m−1·s−1 and 0.29 s−1, respectively.