Plenty of rooftops with few neighbours occupied by young breeding Yellow-legged Gulls (Larus michahellis): Does this occur at the expense of their health condition?

Gulls, as largely flexible opportunistic individuals, have been increasingly breeding in many cities around the world, but it is still unclear whether urban habitats are of equal or higher quality than traditional natural habitats or represent an ecological trap with immediate reproductive benefits but longer-term detrimental consequences to health. Here we present a study of breeding parameters (nest density, egg dimensions, clutch size, hatching success and adult body condition) and physiological parameters (erythrocyte sedimentation rate, heterophil/lymphocyte ratio, haemoglobin concentration and measurements of oxidative stress) as indicators of the general health condition of Yellow-legged Gull Larus michahellis adults and chicks from natural and urban colonies. Yellow-legged Gulls in the largest urban area (Porto) laid smaller eggs and clutches, showed a significantly lower occurrence of inflammatory processes in chicks, and showed a slower early chick growth than in the natural colony of Deserta. This suggests that urban gulls might be facing important trade-offs between the advantages of breeding in lower density urban colonies, with fewer intraspecific interactions and a lower disease transmission probability, and the disadvantages of having an anthropogenic diet usually lower in nutritional value.     

Seasonal changes in photosynthetic capacity of leaves of kiwifruit (Actinidia deliciosa) vines

A simplified procedure for the assay and purification of an enzyme which activates a galactosyltransferase (EC 2.4.1.96) involved in volume regulation of the unicellular alga Poterioochromonas malhamensis (Peterfi) is described. The enzyme was extracted with water from membranes, followed by chromatography on DEAE-Sephacel, phenyl-Sepharose and fetuin-agarose. Its proteinase activity was demonstrated by cleavage of oxidized insulin A- and B-Chains. The predominant cleavage site of the oxidized A-chain is the peptide bond between ¹³Leu and ¹⁴Tyr whereas ¹⁶Leu-¹⁷Glu is also hydrolyzed with minor activity. Besides this chymotrypsin-like endopeptidase activity some carboxypeptidase activity was also observed.     

Relations between stomatal closure, leaf turgor and xylem vulnerability in eight tropical dry forest trees

This study examined the linkage between xylem vulnerability, stomatal response to leaf water potential (Ψ_L), and loss of leaf turgor in eight species of seasonally dry tropical forest trees. In order to maximize the potential variation in these traits species that exhibit a range of leaf habits and phenologies were selected. It was found that in all species stomatal conductance was responsive to Ψ_L over a narrow range of water potentials, and that Ψ_L inducing 50% stomatal closure was correlated with both the Ψ_L inducing a 20% loss of xylem hydraulic conductivity and leaf water potential at turgor loss in all species. In contrast, there was no correlation between the water potential causing a 50% loss of conductivity in the stem xylem, and the water potential at stomatal closure (Ψ_SC) amongst species. It was concluded that although both leaf and xylem characters are correlated with the response of stomata to Ψ_L, there is considerable flexibility in this linkage. The range of responses is discussed in terms of the differing leaf‐loss strategies exhibited by these species.     

A SURVEY OF SIZES AND WEIGHTS OF BEMISIA TABACI (HOMOPTERA:ALEYRODIDAE)B BIOTYPE LIFE STAGES FROM FIELD GROWN COTTON AND CANTALOUPES

Abstract Size and weight measurements were made for all the life stages of Bemisia tabaci (Gennadius) B biotype from field grown cotton ( Gossypium hirsutum L.) and cantaloupe ( Cucumis melo L., var. cantalupensis ) in Phoenix, AZ and Fargo, ND, USA in 2000 and 2001. Nymphal volumes were derived from the measurements. The average nymphal volume increase for settled 1 st to the late 4th instar was exponential. The greatest increase in body volume occurred during development from the 3rd to early 4th instar. Nymphs on cotton leaves were wider, but not longer compared with those on cantaloupe. Ventral and dorsal depth ratios of nymphal bodies from 1 st to late 4th instars from cantaloupe leaves were significantly greater compared with those from cotton leaves. During nymphal development from 1st to 4th instar, the average (from the two host species) ventral body half volume increased by nearly 51 times compared with an increase of 28 times for the dorsal body half volume. Adult female and male average lengths, from heads to wing tips, were 1 126 μm and 953 μm, respectively. Average adult female and male weights were 39 and 17 μg, respectively. Average widths, lengths, and weights of eggs from cotton and cantaloupe were, 99 μm, 197 μm, and 0.8 μg, respectively. Average widths, lengths, and weights for exuviae of non-parasitized nymphs from both cotton and cantaloupe were 492 μm, 673 μm, and 1.20 μg, respectively; and widths, lengths, and weights of parasitized nymph exuviae were 452 μm, 665 μm, and 3.62 μg, respectively. Both exuviae from non-parasitized and parasitized nymphs from cotton leaves were wider, longer, and heavier than those from cantaloupe leaves.     

Inclusion volume solid-phase synthesis

Solid-phase synthesis of peptides was carried out using only the volume of the solvent included in the swollen solid-phase resin beads [inclusion volume synthesis]. This approach enables (i) the use of higher concentrations of activated amino acids, resulting in increased coupling rates, (ii) drastically decreased consumption of solvents, and (iii) the construction of multiple peptide synthesizers having virtually no reaction vessels.     

Cell Swelling Activates Phospholipase A2 in Ehrlich Ascites Tumor Cells

Ehrlich ascites tumor cells, loaded with ³H-labeled arachidonic acid and ¹⁴C-labeled stearic acid for two hours, were washed and transferred to either isotonic or hypotonic media containing BSA to scavenge the labeled fatty acids released from the cells. During the first two minutes of hypo-osmotic exposure the rate of ³H-labeled arachidonic acid release is 3.3 times higher than that observed at normal osmolality. Cell swelling also causes an increase in the production of ¹⁴C-stearic acid-labeled lysophosphatidylcholine. This indicates that a phospholipase A₂ is activated by cell swelling in the Ehrlich cells. Within the same time frame there is no swelling-induced increase in ¹⁴C-labeled stearic acid release nor in the synthesis of phosphatidyl ¹⁴C-butanol in the presence of ¹⁴C-butanol. Furthermore, U7312, an inhibitor of phospholipase C, does not affect the swelling induced release of ¹⁴C-labeled arachidonic acid. Taken together these results exclude involvement of phospholipase A₁, C and D in the swelling-induced liberation of arachidonic acid. The swelling-induced release of ³H-labeled arachidonic acid from Ehrlich cells as well as the volume regulatory response are inhibited after preincubation with GDP_βS or with AACOCF₃, an inhibitor of the 85 kDa, cytosolic phospholipase A₂. Based on these results we propose that cell swelling activates a phospholipase A₂—perhaps the cytosolic 85 kDa type—by a partly G-protein coupled process, and that this activation is essential for the subsequent volume regulatory response. Received: 23 July 1996/Revised: 17 June 1997     

Changes in organic solutes,volume, energy state,and metabolism associated with osmotic stress in a glial cell line: A multinuclear NMR study

Diffusion-weighted in vivo¹H-NMR spectroscopy of F98 glioma cells embedded in basement membrane gel threads showed that the initial cell swelling to about 180% of the original volume induced under hypotonic stress was followed by a regulatory volume decrease to nearly 100% of the control volume in Dulbecco's modified Eagle's medium (DMEM) but only to 130% in Krebs-Henseleit buffer (KHB, containing only glucose as a substrate) after 7 h. The initial cell shrinkage to approx. 70% induced by the hypertonic stress was compensated by a regulatory volume increase which after 7 h reached almost 100% of the control value in KHB and 75% in DMEM.¹H-,¹³C-and³¹P-NMR spectroscopy of perchloric acid extracts showed that these volume regulatory processes were accompanied by pronounced changes in the content of organic osmolytes. Adaptation of intra- to extracellular osmolarity was preferentially mediated by a decrease in the cytosolic taurine level under hypotonic stress and by an intracellular accumulation of amino acids under hypertonic stress. If these solutes were not available in sufficient quantities (as in KHB), the osmolarity of the cytosol was increasingly modified by biosynthesis of products and intermediates of essential metabolic pathways, such as alanine, glutamate and glycerophosphocholine in addition to ethanolamine. The cellular nucleoside triphosphate level measured by in vivo³¹P-NMR spectroscopy indicated that the energy state of the cells was more easily sustained under hypotonic than hypertonic conditions.To whom to address reprint requests.     

Relationship of scrotal circumference and testicular volume to age and body weight in the swamp buffalo (Bubalus bubalis)

Scrotal circumference (SC) and testicular volume (TV) were measured in 65 swamp buffalo bulls ranging in age from 7 to 60 months and weighing 130 kg to 560 kg. Ages and body weight (BW) were recorded for each male at the time of measurement to find out if they correlated with SC and TV. SC and TV increased linearly and correlated significantly with age and BW (SC vs age: r = 0.74, p<0.01; SC vs BW: r = 0.88, p<0.01; TV vs BW: r = 0.82, p<0.01). SC measurements ranged from 15.1 +/- 1.1 cm to 24.0 +/- 0.4 cm for ages ranging from 10.0 +/- 0.6 to 48.5 +/- 6.3 months, revealing that testicular size in swamp buffaloes was very much smaller than domestic cattle. The SC norms distributed with age would be useful in the evaluation of swamp buffalo males for breeding soundness.     

Interrelationships between water and cellular metabolism inArtemia cysts

Cysts of the crustaceanArtemia are a useful model for studies on intracellular water because they are capable of essentially complete and reversible desiccation. We have used a variety of techniques on this system, the present work being an attempt to estimate the density of intracellular water (ρ_w). The density of individual cysts was evaluated from sedimentation velocity. Heptane displacement methods were used to determine the volume of a known mass of cysts, from which the density was calculated. The two methods produce comparable results. It was shown that the densities and water contents of large masses of cysts accurately reflect those of individual cysts. Cyst densities (ρ_c) were determined over the entire range of water content from 0 to 0.63 weight fraction of water (W _f), and temperature dependence was measured for 0.61W _f over 2–41°C. The following refer to 25°C. No marked change was detected in ρ_c until the water content exceeded 0.15W _f, at which ρ_c decreased as a linear function of Wf to maximum water content. However, the cyst does not behave ideally in the sense that the densities of the nonaqueous components and added water are not additive as a function ofW _f. The partial specific volume of water in cysts at maximum hydration was estimated to be 3% larger than that of pure water. These observations are compared with density measurements on other systems, and with previous findings on the physical properties of water in this system.     

Rapid methods for the characterization of unilamellar phospholipid vesicles. Application to studies on fatty acid donor and acceptor properties of membranes and fatty acid binding proteins

Vesicles having diameters from 20 to 200 nm were prepared from egg-yolk phosphatidylcholine (PC) and were separated as well as analyzed by methods that can be carried out with standard laboratory equipment. Gel-chromatography on Sephacryl S 1000 was adapted for expeditious size analysis of vesicles as well as for isolation of vesicle populations having a narrow range of diameters. The internal volume of vesicles was derived from enzymic tests for PC and for glucose encapsulated. Size analysis and enzymic determinations provided a convenient check for the lamellarity of membranes produced.Fatty acids and fatty acid binding proteins (FABPs) must interact in vivo in the presence of cellular membranes. As a model, interactions between unilamellar vesicles, anthroyloxypalmitic acid (A16:0) and FABPs were studied with the aid of gel-chromatographic methods elaborated and of fluorescence spectroscopy. FABP from bovine heart donated A16:0 to membranes, whereas FABP from bovine liver removed this fatty acid from vesicle membranes. The results revealed characteristic differences between cardiac and hepatic FABPs with regard to binding a fatty acid.