Haematological studies on the prewintering and wintering frog, Rana esculenta

1. A study of the haematology of the frog Rana esculenta including erythrocyte count (RBC), haemoglobin content (Hb), haematocrit (HCT), mean cell volume (MCV), mean corpuscular haemoglobin (MCH), mean corpuscular haemoglobin concentration (MCHC) and erythrocyte size as a function of prewinter and winter was made. 2. The RBC count and Hb were significantly higher in contrast to MCV and MCH values during prewinter in both sexes. 3. The surface area to volume ratio was higher in prewinter whereas the length to width ratio (eccentricity) of the cytosome and nucleus was significantly higher during winter in both sexes. 4. Sexual differences in the erythrocyte count, Hb content and the surface area to volume ratio were also observed. 5. The physiological significance of these observations are reported for Rana esculenta.     

Metabolism of red blood cells after short-term exercise in rats

The aim of this study was to determine the changes of the basic parameters of the erythrocyte system and the activity of some red blood cell (RBC) enzymes prior to and after a single physical effort leading to exhaustion. The study was carried out on male Wistar rats subjected to running on an electric rotating drum at a speed of 25 m/min. A single exercise caused a decrease in the RBC count, haemoglobin concentration (Hb) and haematocrit (Hct) by 21.9, 16.7 and 16.1%, respectively, and an increase in the reticulocyte count (Ret) by 661.5%. The exercise triggered also changes in the activities of some erythrocytic enzymes: pyruvate kinase (PK) activity increased by 12.4%, glucose-6-phosphate dehydrogenase (G6PD) by 37.8%, glutathione reductase (GR) by 30.8% and acetylcholinesterase (AChE) by 248.7%. These increases in the activities of RBC enzymes can be explained by an increase in the red cells turn-over.     

Development of hematological respiratory variables in late chicken embryos: the relative importance of incubation time and embryo mass

Oxygen demand increases during embryonic development, requiring an increase in red blood cells (RBCs) containing hemoglobin (Hb) to transport O(2) between the respiratory organ and systemic tissues. A thorough ontogenetic understanding of the onset and maturation of the complex regulatory processes for RBC concentration ([RBC]), Hb concentration ([Hb]), hematocrit (Hct), mean corpuscular indices (mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH) and mean corpuscular hemoglobin concentration ([MCHb])) is currently lacking. We hypothesize that during the last half of incubation when the respiratory organ (the chorioallantoic membrane) envelops most of the egg contents, mean corpuscular indices will stabilize. Accordingly, Hct, [RBC] and [Hb] must also all change proportionally across development. Further, we hypothesize that the hematological respiratory variables develop and mature as a function of incubation duration, independently of embryonic growth. As predicted, a similar increase in Hct (from 18.7±0.6% on day 10 (d10) to 34.1±0.5% on d19 of incubation), [RBC] (1.13±0.03×10(6)/μL to 2.50±0.03×10(6)/μL) and [Hb] (6.1±0.2 g% to 11.2±0.1 g%) occurred during d10-19. Both [RBC] and [Hb] demonstrated high linear correlation with Hct, resulting in constant [MCHb] (~33 g% from d10 to d19). The decrease in MCV (from ~165 μ(3) on d10 to ~140 μ(3) on d13) and MCH (~55 pg to ~45 pg) during d10-13, may be attributed to a changeover from larger primary to smaller secondary and adult-type erythrocytes with MCV and MCH remaining constant (~140 μ(3) and ~45 pg respectively) for the rest of the incubation period (d13-19). Hematological respiratory values on a given incubation day were identical between embryos of different masses using either natural mass variation or experimental growth acceleration, indicating that the hematological variables develop as a function of incubation time, irrespective of embryo growth.     

Haematology of the grass snake Natrix natrix natrix L.

1. Haematological parameters and cytomorphological picture of circulating blood of the grass snake Natrix natrix natrix L. were studied. Mean annual values of the haemoglobin concentration, haematocrit level, red cell counts, erythrocytes indices, erythrocyte sedimentation rate, thrombocyte and leucocyte counts, per cent composition of white blood cells and size of morphotic elements were determined for a population sample (N = 154) of the species, considering the sex of snakes. 2. Parameters of red blood cell system (RCC, Hb, Hct) were statistically significantly higher in males, remaining indices showed no statistically significant differences. 3. A strict positive correlation was found between RCC, Hb and Hct in the studied sample. 4. Cytomorphology of blood is presented in microphotographs. 5. In the discussion haematological data for the grass snake and other snakes are compared.     

DEVELOPMENT OF HEMOGLOBIN, HEMATOCRIT, AND ERYTHROCYTE VALUES IN GALÁPAGOS FUR SEALS

We studied the ontogeny of hemoglobin concentration, hematocrit and erythrocyte counts in the Galapagos fur seal ( Arctocephalus galapagoensis , Heller 1904). Two hundred and fifty-three animals were sampled between the ages of 22 d and > 8 yr, of which 46 were adult females. Body mass increased steadily with age from 6.1 ± 1.2 kg in 1-mo-old pups ( n = 27) to 28.5 ± 3.3 kg in adult females. Even adult females increased in mass with age. Hemoglobin (Hb), hematocrit (Hct), and red blood cell (RBC) values all increased in a logarithmic fashion with age up to 2 yr. Blood values for pups were Hct: 35.5 ± 4.1%; Hb: 12.9 ± 1.3 g/dl; RBC: 4.1 ± 0.3·10⁶/μl. Half-year-old fur seals (Hct: 42.1 ± 3.2%; Hb: 15.7 ± 1.3 g/dl; RBC: 4.9 ± 0.5·10⁶/μl; n = 50) were the oldest age group to show significantly lower blood values than adult females ( P < 0.001 for all three parameters). Yearling blood values (Hct: 47.2 ± 3.6%; Hb: 17.3 ± 1.6 g/dl; RBC: 5.6 ± 0.4·10⁶/μl; n = 56) did not differ significantly from those of adult females ( P < 0.32; P < 0.26; P < 0.23, respectively). Blood values of adult females were lower than those of 2-yr-olds (Hct: 49.6 ± 2.4%; Hb: 18.5 ± 1.2 g/dl; RBC: 5.7 ± 0.3·10⁶/μl; n = 31). These differences were significant only for RBCs ( P < 0.003). Up to the age of 1 yr, age was the best predictor for blood values, thereafter mass tended to be a better predictor. Female juveniles between the ages of 150 and 600 d had higher blood values than same-age males. The relationship of blood value development to diving activity is briefly described and the results are compared to values of other marine mammals. Ontogeny is discussed in relation to the development of these blood values in terrestrial mammals.     

Brood provisioning rates and fledgling behavior of Cordilleran Flycatchers in southwestern Colorado

The behavior of young songbirds after fledging is one of the least understood phases of the breeding cycle, although parental provisioning rates and movement of fledglings are key to understanding life history evolution. We studied Cordilleran Flycatchers (Empidonax occidentalis) at two sites in southwestern Colorado, USA, from 2012 to 2017. We banded and sexed breeding adults to determine the relative contributions of males and females to nestling and fledgling care, and attached radio‐transmitters to nestlings to facilitate observations of brood behavior after fledging. Females made 60% and 78% of total observed feedings of nestlings and fledglings, respectively. Parental provisioning rates increased with nestling age, and per‐nestling provisioning rates increased with brood size. Parental provisioning rates declined just before fledging, then increased just after fledging. Fledging times of individuals in broods were asynchronous and concentrated during the late afternoon and early evening. Males stopped caring for fledglings before females even though this species is single‐brooded, with some late‐season broods being abandoned by males. Broods spent the first three weeks after fledging within 400 m of nests, after which they began to disperse. Most aspects of the breeding biology of Cordilleran Flycatchers in our study, including the duration of nestling and fledging periods, female‐dominated provisioning, and movement patterns of fledglings, were similar to those of other Empidonax species. However, the times when young fledged were not concentrated in the morning as reported in most other songbirds, and this result warrants additional study of the timing of fledging in ecologically and taxonomically similar species. The increased per‐nestling provisioning rate with increasing brood size was unexpected, and additional study is needed to determine if this increase results from a trade‐off between adult annual survival and productivity favoring increased provisioning of young in larger broods, or from the existence of high‐quality individuals where larger clutches and higher provisioning rates are linked.     

Response of red cell and plasma volume to prolonged training in humans

To clarify the role of progressive heavy training on vascular volumes and hematologic status, seven untrained males [maximal O2 uptake (VO2max) = 45.1 +/- 1.1 (SE) ml.kg-1.min-1] cycled 2 h/day at an estimated 62% of VO2max. Training was conducted five to six times per week for approximately 8 wk. During this time, VO2max increased (P less than 0.05) by 17.2%. Plasma volume (PV) measured by 125I increased (P less than 0.05) from 3,068 +/- 104 ml at 0 wk to 3,490 +/- 126 ml at 4 wk and then plateaued during the remaining four wk (3,362 +/- 113 ml). Red cell (RBC) mass (RCM) measured by 51Cr-labeled RBC did not change during the initial 4 wk of training (2,247 +/- 66 vs. 2,309 +/- 128 ml). As well, no apparent change occurred in RCM during the final 4 wk of training when RCM was estimated using PV and hematocrit (Hct). Collectively, PV plus RCM, expressed as total blood volume (TBV), increased (P less than 0.05) by 10% at 4 wk and then stabilized for the final 4 wk. During the initial phase of training, reductions (P less than 0.05) were also noted in Hct (4.6%), hemoglobin (Hb, 4.0%), and RBC count (6.3%). In contrast, an increase in mean cell volume (MCV, 1.7%) and mean cell Hb (2.3%) was observed (P less than 0.05). From 4 to 8 wk, no further changes (P greater than 0.05) in Hb, RBC, and MCV were found, whereas both mean cell Hb and Hct returned to pretraining levels.(ABSTRACT TRUNCATED AT 250 WORDS)     

Lack of prominent compensatory polycythemia in traditional native Andeans living at 4,200 meters

Red blood cell count (RBC), hemoglobin concentration ([Hb]) and hematocrit (Hct) were measured in 303 male Quechua children and adults, aged 6 to 57 years, living a lifestyle as traditional pastoralists and horticulturalists at a mean altitude of 4,200 m in the Southern Peruvian Andes. Values for RBC, [Hb], and Hct increased with age from middle childhood to young adulthood. However, among adults there was no significant association between age and any of these three parameters. Overall, there was approximately a 10-12% increase in the RBC, [Hb], and Hct above sea-level norms for all age groups. Mean corpuscular volume (MCV) and mean corpuscular hemoglobin (MCH) showed a slight but significant increase with age in children and adolescents, but the mean corpuscular hemoglobin concentration (MCHC) did not. We conclude that the study of highland Quechua Indians, living a traditional lifestyle as pastoralists and horticulturalists, does not support the long-held belief that altitude hypoxia provokes a dramatic compensatory polycythemia in healthy Andeans.     

Fitness consequences of timing of breeding in birds: date effects in the course of a reproductive episode

In seasonal environments, avian reproductive performance almost generally declines in the course of the season. Quantifying the associated fitness consequences of timing of breeding, i.e. of date‐related factors, is important for understanding the evolution of temporal patterns in avian life‐histories and for predicting consequences of climate change. The seasonal decline can also be caused by an effect of parental quality: individuals with high phenotypic quality may breed early. The results of existing experimental studies investigating whether date or quality effects cause the seasonal decline are inconsistent, indicating that both mechanisms might be involved. However, it remains unclear to what extent the confounding effect of quality occurs and what the fitness consequences of timing per se over a whole breeding episode are. In a cross‐fostering experiment using the barn swallows’ second broods we evaluated the causes for the seasonal decline in reproductive performance for three distinct periods of a reproductive attempt, the early nestling period, the late nestling period and the post‐fledging period, and we assessed the overall fitness consequences of timing per se. A seasonal decline in juvenile feather growth rate was mainly due to date effects in the late nestling period, although we determined quality effects during early nestling development. Date effects on survival were present in the post‐fledging period, but not in the nestling period. The decline in feather length due to date effects in the nestling period accounted for 9% of the seasonal decline in post‐fledging survival, whereas date effects arising only in the post‐fledging period caused 91% of the decline. These results suggest that date effects increase in the course of a reproductive episode. Thus, the benefits of an early timing of breeding can be quantified only when considering also the post‐fledging period. We suggest that the timing of breeding evolved through a trade‐off between date‐related benefits and quality‐related costs of early breeding.     

The process of fledging in the Mountain Bluebird

Fledging is a critical event in the avian breeding cycle, but remains unstudied in almost all species. As a result, little is known about factors that cause nestlings to leave nests. We documented fledging behavior in a box‐nesting population of Mountain Bluebirds (Sialia currucoides) using radio‐frequency identification. We attached a passive integrated transponder (PIT tag) to the leg of each nestling in 40 nests. An antenna checked for the presence of a transponder signal (i.e., a nestling) at nest‐box entrances every 2 s. The time of last detection of a nestling was taken as the time that nestling fledged. We found that fledging began when the oldest nestlings were 15–22 d old. Broods that were ahead in development, as measured by primary feather length, fledged at relatively younger ages. All nestlings fledged on the same day at 33 nests (83%) and over 2 d at remaining nests. When all nestlings fledged on the same day, fledging usually began in the morning and median time between the first and last fledging was 55 min (range = 2.3 min–10.6 h). When young fledged over 2 d, fledging always began >8 h after sunrise and usually just one nestling fledged the first day, suggesting that this fledging may have been accidental. Clutches in our population often hatch asynchronously, which sets up a hierarchy within broods in developmental state, size, and competitive ability. In such situations, fledging may be initiated by one of the most‐developed and hence most‐competitive nestlings in a brood, presumably when it reaches a certain threshold state of development. Alternatively, fledging may begin when a less‐developed, less‐competitive, and probably hungrier nestling leaves the nest, presumably to gain better access to food. We used the proportion of time that a nestling was able to occupy the nest‐box entrance late in the nestling stage, waiting to intercept parents with food, as an index of nestling competitive ability. Assuming that the number of nest entrance detections reliably indicates nestling competitive ability, we found that the most‐competitive nestling fledged first at over half of all nests, supporting the notion that fledging usually begins when oldest nestlings reach a threshold state of development.     

Effect of triploidy on turbot haematology

This study was carried out to compare key haematological features of diploid (2n) and triploid (3n) turbot as a first step towards the assessment of the ability of 3n turbot to withstand sub-optimal culture conditions. Morphometric indices of erythrocytes were determined on blood smears by light microscopy. Triploidy significantly (P<0.001) increased all morphometric indices measured in the erythrocytes, including size, surface, and volume, except for the size of minor nuclear axis. The increase in cell size was larger for the major (31.0%) than for the minor (8.3%) axis, thus rendering erythrocytes of 3n turbot more ellipsoidal. The increase in erythrocyte volume (45.9%) was close to the theoretical expected 50% increase as a result of one extra chromosome set. Haematological indices were measured automatically by a haematological Coulter Counter. Triploid turbot had lower numbers of red blood cells (RBC: 1.84 cells pL(-1) in 2n vs. 1.27 cells pL(-1) in 3n; P<0.001) but they were of a larger size (Mean corpuscular volume [MCV]: 145.51 fL in 2n vs. 181.78 fL in 3n; P<0.001). However, the decrease in RBC was not compensated by the increase in MCV, and thus, triploidy decreased the haematocrit (Hct: 26.80% in 2n vs. 23.11% in 3n; P<0.001) and total blood haemoglobin concentration (Hb: 73.74 g l(-1) in 2n vs. 67.54 g l(-1) in 3n; P<0.05). In contrast, mean corpuscular hemoglobin (MCH: 40.27 pg in 2n vs. 53.28 pg in 3n; P<0.001) was higher for 3n turbot as a result of their larger erythrocytes although MCH concentration (MCHC: 0.28 pg fL(-1) in 2n vs. 0.29 pg fL(-1) in 3n did not significantly differ. RBC, Hct and MCV were also determined manually using light microscopy. In general, discrepancies between the two methods were small (overall approximately 7%) but the Coulter Counter tended to overestimate RBC and Hct (and thus to underestimate MCV). Nevertheless, relative differences between ploidies were very similar, thus verifying triploidy-associated changes in hematological features. These changes, as determined in the present study, are essential when evaluating the feasibility of triploid turbot for intensive aquaculture systems in which unfavorable situations may occur.     

Do parents play a role in the timing and process of fledging by nestling Mountain Bluebirds?

What causes young birds to leave nests remains unclear for almost all altricial species. For many years, the assumption was that parents often controlled the time of fledging by coaxing young from nests, e.g., by holding food within view, but out of reach, of nestlings. This assumption, though, was based solely on scattered anecdotal reports of such behavior. We used continuous video‐recording of nests to assess the role of parents, if any, in the timing and process of fledging of cavity‐nesting Mountain Bluebirds (Sialis currucoides). We placed perches ~50 cm in front of nest‐box entrances to give parents ample opportunity to display food to nestlings. We found no evidence that parents routinely initiated the fledging process. On the day of fledging, parents did not perch on supplemental perches with food more often, or for longer periods of time, than on the day before fledging. Also, after going to nest‐box entrances, parents never held food away from a nestling reaching for the food. Parents were usually absent (16 of 19 cases) when the first nestling fledged. In the remaining three cases, a parent perched with food in view of a nestling for 8, 15 and 65 s, respectively, just before that nestling fledged. Although these might have appeared to be attempts at coaxing, in each case, the parent was encountering, for the first time, a nestling partially emerging from the nest entrance. Parents may simply have hesitated to approach nests because the nestling's position prevented parents from delivering food in the normal manner. Finally, the rate at which parents fed nestlings on the day of fledging did not differ from the rate the day before, suggesting that parents do not try to use hunger to induce fledging. Our results are consistent with previous research suggesting that, in Mountain Bluebirds, it is a nestling that initiates fledging, typically when it reaches some threshold state of development.     

Testosterone action on erythropoiesis does not require its aromatization to estrogen: Insights from the testosterone and estrogen treatment of two aromatase-deficient men

Androgens act on erythropoiesis, but the relative role of testosterone (T) and estradiol (E₂) on erythropoietic parameters in men is a poorly investigated issue. In order to evaluate separately the effects on erythropoiesis of high-dose T administration alone and of physiological dose of E₂ administration alone two adult men with aromatase deficiency were assessed before and during each treatment. Blood cell count, hemoglobin (Hb), hematocrit (Hct), erythrocyte mean cell volume (MCV), erythrocyte mean corpuscular hemoglobin (MCH), erythrocyte mean corpuscular hemoglobin concentration (MCHC), serum ferritin, iron and total iron-binding capacity (TIBC), serum erythropoietin, serum total testosterone and estradiol were evaluated. Hb, Hct and red cell count rose during testosterone treatment, consistently with the increase in circulating testosterone, but failed to increase during estradiol treatment. A decrease in Hb, Hct and red cell count was recorded in one of the two subjects during estradiol treatment, with a concomitant decrease in serum testosterone. Circulating T alone is capable of and sufficient to influence erythropoiesis, especially at supraphysiological dosage, while circulating E₂ have not the same effect on erythropoietic parameters, suggesting the hypothesis that the erythropoietic changes induced by androgens are not mediated via its aromatization to estrogens.     

How does an increase in minimum daily temperatures during incubation influence reproduction in the great tit Parus major?

Temperature variation affects all life stages of organisms, especially early development, and considering global warming, it is urgent to understand precisely its consequences. In egg‐laying species, incubation behaviour can buffer embryo developmental temperature variation and influence offspring development. We experimentally investigated the effect of an increase in minimum daily nest temperature during incubation in the great tit Parus major, by placing a hand warming pad under the nest in the evenings. As compared to controls, the experimental treatment increased nest temperature at night by an average of 4°C, and this increase carried over to the following day. We measured the consequences of this mainly nocturnal temperature increase during incubation on 1) parental behaviour (incubation and nestling feeding), 2) parental health (quantified by body condition, immune status, physiological and oxidative stress) and 3) reproductive success (nestling body condition, growth, i.e. mass gain, hatching and fledging success, and nestling immune status, physiological and oxidative stress). This study yielded three major results. First, we found that heating the nest did not change the duration of incubation as compared to controls. Second, increasing nest temperature during incubation decreased nestling feeding behaviour but did not affect parental health in terms of body condition, immune status, physiological and oxidative stress. Third, nestling mass at hatching was greater but nestling mass gain was slower in heated nests than in control nests, resulting in similar fledging mass. The present study demonstrates that increased environmental temperatures during incubation influenced nestling development in the great tit and especially hatchling mass, which might produce long‐term life history consequences.     

Restorative effect of Azadirachta indicab aqueous leaf extract dip treatment on haematological parameter changes in Cyprinus carpio (L.) experimentally infected with Aphanomyces invadans fungus

Common carp, Cyprinus carpio (40 ± 10 g) were inoculated through intramuscular route (2.5 × 10⁵ cfu ml^?1) with the fungal pathogen, Aphanomyces invadans. In the infected group, the total erythrocyte count (RBC), total leucocyte count (WBC), haematocrit (Hct), haemoglobin (Hb), lymphocyte (LYM), monocyte (MON), neutrophil (NEU) and eosinophil (EOS) deviated significantly (P < 0.05) from control values on days 24 and 36. Beginning on day 12 of infection, the fishes were dip treated for 24 days for 5 min daily in water incorporated with 1% aqueous leaf extract of Azadirachta indica (neem); the induced lesion gradually healed and the haematological values attained were near normal (P > 0.05) when compared with the control group.     

The interaction of haemoglobin, magnesium, organic phosphates and band 3 protein in nucleated and anucleated erythrocytes

The anion influx was measured in order to study the interaction among organic phosphates, magnesium, haemoglobin and the N-terminal of the cytoplasmic domain of band 3 protein in human, chicken and trout erythrocytes. The rate constant for SO(4)(2-) influx in human and trout erythrocytes increased significantly when it was measured with an increased concentration of intracellular Mg(2+). The SO(4)(2-) influx was also measured in human erythrocyte ghosts in the presence and absence of Mg(2+). The smaller activation provoked by Mg(2+) in ghosts could be caused by the presence of a small quantity of haemoglobin which remained inside. The SO(4)(2-) uptake in chicken erythrocytes in the presence and in absence of Mg(2+) was characterized by very similar rate constants. The results suggest that the small increase in intracellular Mg(2+) in the erythrocytes involves an increase in the formation of Mg(2+)-ATP and Mg(2+)-2,3 BPG complexes reducing the affinity of the organic phosphates for Hb. This new situation may influence the functions of the anion transporter with consequent variations of SO(4)(2-) influx throughout the erythrocyte membrane in human and in trout erythrocytes, whereas in chicken RBCs this function cannot occur and, in fact, no increase in sulphate influx was noticeable. The measurement of Hb/O(2) affinity by the use of alternating fixed and variable concentrations of organic phosphates and Mg(2+), confirms the interactions between these elements and their effect on the mechanism of the affinity. When we measured the sulphate influx in the presence of DIDS we found some differences in the three types of cells.     

Habitat and year-to-year variation in haemoglobin concentration in nestling blue tits Cyanistes caeruleus

Nutrition during the time spent at the nest is critical for the development of the body condition in altricial birds, including nestling blue tits (Cyanistes caeruleus). Trophic conditions tend to be variable in time and space, which should influence the physiological condition of growing birds. In this paper, we consider haemoglobin concentration as a general indicator of chick physiological condition. Its variation is both consistent within broods and indicative/prognostic of survival from the moment of hatching to fledging. We show that haemoglobin concentration of nestling blue tits is on average higher in years and habitats characterised by rich abundance of caterpillars than under poor caterpillar availability. Haemoglobin seems to quite exactly reflect even relatively subtle differences in trophic conditions.     

Multiple responses to increasing spring temperatures in the breeding cycle of blue and great tits (Cyanistes caeruleus,Parus major)

Many bird species start laying their eggs earlier in response to increasing spring temperatures, but the causes of variation between and within species have not been fully explained. Moreover, synchronization of the nestling period with the food supply not only depends on first‐egg dates but also on additional reproductive parameters including laying interruptions, incubation time and nestling growth rate. We studied the breeding cycle of two sympatric and closely related species, the blue tit Cyanistes caeruleus and the great tit Parus major in a rich oak‐beech forest, and found that both advanced their mean first‐egg dates by 11–12 days over the last three decades. In addition, the time from first egg to fledging has shortened by 2–3 days, through a decrease in laying interruptions, incubation time (not statistically significant) and nestling development time. This decrease is correlated with a gradual increase of temperatures during laying, suggesting a major effect of the reduction in laying interruptions. In both species, the occurrence of second clutches has strongly decreased over time. As a consequence, the average time of fledging (all broods combined) has advanced by 15.4 and 18.6 days for blue and great tits, respectively, and variance in fledging dates has decreased by 70–75%. Indirect estimates of the food peak suggest that both species have maintained synchronization with the food supply. We found consistent selection for large clutch size, early laying and short nest time (laying to fledging), but no consistent changes in selection over time. Analyses of within‐individual variation show that most of the change can be explained by individual plasticity in laying date, fledging date and nest time. This study highlights the importance of studying all components of the reproductive cycle, including second clutches, in order to assess how natural populations respond to climate change.     

Biochemical and hemato-immunological parameters in juvenile beluga (Huso huso) following the diet supplemented with nettle (Urtica dioica)

The present study investigated the effects of different dietary nettle (Urtica dioica) levels on biochemical, hematological and immunological parameters in beluga (Huso huso). Fish were divided into 4 groups before being fed for 8 weeks with 0%, 3%, 6% and 12% of nettle. The blood samples were collected on week 4 and 8. The use of nettle did not significantly change the mean cell volume, mean cell haemoglobin, lymphocytes, eosinophils, albumin, glucose, alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase and lysozyme activity on week 4 and 8. After 4 weeks, the total red blood cell (RBC) and hematocrit (Ht) showed a significant increase in 12% nettle group compared to the 3% nettle and control groups but haemoglobin (Hb) had a significant change in 12% nettle compared to the control. At the same time was not found a significant change in the mean cell haemoglobin concentration (MCHC), total white blood cell (WBC), neutrophils, respiratory burst activity (RB), total immunoglobulin (Ig) and total protein (TP), triglyceride (Tri) and cholesterol (Chol). After 8 weeks, the fish treated with nettle exhibited significantly increase in neutrophil and Hb levels compared to the control and between treatment groups, 12% nettle group shown the highest Hb while RBC and Hct values significantly rose in fish fed by 12% compared to the control. Supplementing 6% and 12% nettle increased the WBC and MCHC compared to the other groups. The group fed 12% showed a highly significant difference in RB, TP and Ig after 8 weeks. However, Tri and Chol were significantly decreased in the juvenile beluga fed by the 6% and 12% nettle diet compared to the other groups. The results suggest that by using this herb there will be an improvement in hemato-biochemical parameters and immune function of juvenile beluga.     

Plasma volume, fluid shifts, and renal responses in humans during 12 h of head-out water immersion.

Changes in plasma volume (PV) throughout 12 h of thermoneutral (34.5 degrees C) water immersion (WI) were evaluated in eight subjects by an improved Evans blue (EB) technique and by measurements of hematocrit (Hct), hemoglobin (Hb), and plasma protein concentrations (Pprot). Appropriate time control studies (n = 6) showed no measurable change in PV. At 30 min of immersion, EB measurements demonstrated an increase in PV of 16 +/- 2% (457 +/- 70 ml). Calculations, however, based on concomitant changes in Hct, Hb, and Pprot showed an increase in PV of only 6.9 +/- 0.9 to 10.0 +/- 0.8% at 30 min of WI. PV values based on EB measurements subsequently declined throughout WI to (but not below) the preimmersion level. Concomitantly, changes in PV calculated from Pprot values remained increased, whereas estimations of changes in PV based on Hct and Hb values returned to prestudy levels after 4 h of immersion. It is concluded that PV initially increases by 16 +/- 2% during WI and does not decline below preimmersion and control levels during 12 h of immersion despite a loss of 0.9 +/- 0.2 liter of body fluid. Furthermore, changes in Hct, Hb, and Pprot do not provide accurate measures of the changes in PV during WI in humans.