Effects of shade treatments on the photosynthetic capacity,chlorophyll fluorescence,and chlorophyll content of Tetrastigma hemsleyanum Diels et Gilg

Tetrastigma hemsleyanum Diels et Gilg was grown under full sunlight and moderate and high levels of shade for one month to evaluate its photosynthetic and chlorophyll fluorescence response to different light conditions. The results showed that T. hemsleyanum attained greatest leaf size and P_n when cultivated with 67% shade. Leaves of seedlings grown with 90% shade were the smallest. Leaf color of plants grown under full sunlight and 50% shade was yellowish-green. The P_n value increased rapidly as PPFD increased to 200 μmol m^?2 s^?1 and then increased slowly to a maximum, followed by a slow decrease as PPFD was increased to 1000 μmol m^?2 s^?1. P_n was highest for the 67% shade treatment and the LSP for this shade treatment was 600 μmol m^?2 s^?1. Full sunlight and 50% shade treatments resulted in significant reduction of ETR and qP and increased NPQ. Chl a, Chl b and total chlorophyll content increased and Chl a/b values decreased with increased shading. Results showed that light intensity greater than that of 50% shade depressed photosynthetic activity and T. hemsleyanum growth. Irradiance less than that of 75% shade limited carbon assimilation and led to decreased plant growth. Approximately 67% shade is suggested to be the optimum light irradiance condition for T. hemsleyanum cultivation.     

Diversity and spatial clustering of shade trees affect cacao yield and pathogen pressure in Costa Rican agroforests

The importance of the spatial organisation of individuals in explaining species coexistence within a community is widely recognised. However, few analyses of spatial structure have been performed on tropical agroforests.The main objective of this study was to highlight the links between spatial organisation of shade trees on the one hand, and shade tree species richness and cacao yield on the other, using data from 29 cacao agroforests in Costa Rica.A method of spatial statistics, Ripley's K-function, was used to analyse the spatial organisation of shade and cacao trees in the study plots. For each stand, the X and Y coordinates of ≥2.5-m-tall trees were recorded. In each plot we also assessed shade tree species richness and cacao yield (with total number of pods = number of pods damaged by frosty pod rot + number of healthy pods).Three types of stands were identified: the first was characterised by significant clustering of shade trees, the highest shade tree species richness (S = 6), and the highest number of damaged pods (139 pods ha^?1 year^?1). The second type was characterised by random spatial organisation of shade trees. The third type showed a trend towards regular organisation. Species richness of shade trees did not differ significantly between the last two types (S = 4 for both), nor did the number of damaged pods (56 pods ha^?1 year^?1 and 67 pods ha^?1 year^?1 respectively).Although the trends were not statistically significant for all the variables in our data set, the clustered spatial structure appears to favour a synergy between environmental (tree species richness), and provisioning (cacao production) services.     

Factors controlling Zostera marina L. growth in the eastern and western Pacific Ocean: Comparisons between Korea and Oregon,USA

Zostera marina distribution is circum-global and tolerates a wide range of environmental conditions. Consequently, it is likely that populations have adapted to local environmental conditions of light, temperature and nutrient supply. We compared Z. marina growth dynamics over a 2-year period in relation to environmental characters at Jindong Bay, South Korea and Yaquina Bay, Oregon, USA. Water temperature in Jindong Bay showed stronger seasonal variation (summer–winter ΔT = 20 °C) than in Yaquina Bay (summer–winter ΔT < 5 °C). Underwater irradiance in Jindong Bay exhibited a winter maximum, while in Yaquina Bay underwater light exhibited a summer maximum. Integrated annual underwater irradiance during 2003 was 2200 and 1200 mol photons m⁻² year⁻¹ in Korea and Oregon, respectively. Z. marina shoot density, biomass and integrated production were not significantly different between the two study sites. Seasonal Z. marina growth in Jindong Bay appeared to be controlled by temperature and light, while the growth pattern in Yaquina Bay suggested light regulation. Several seagrass parameters were correlated to phosphate concentrations, even though nutrients did not appear limiting. Despite differences in environmental factors, relative growth rates and temporal growth dynamics between study sites, integrated annual leaf production was quite similar at 335 and 353 g DW m⁻² year⁻¹ in the Jindong and Yaquina Bay study sites. We suggest that Z. marina net productivity is acclimated to the local environmental conditions and may be a general characteristic of temperate seagrass populations.     

Do fruit sunburn control measures affect leaf photosynthetic rate and stomatal conductance in ‘Royal Gala’ apple?

A field study was conducted on a 5-year-old orchard of ‘Royal Gala’ apple (Malus domestica Borkh.) in Stellenbosch, South Africa, to investigate whether the measures employed to control sunburn in fruit, viz., evaporative cooling, Surround WP and 20% black shade net affect leaf photosynthetic gas exchange attributes in comparison to untreated control during the 2003/2004 season. Shade net significantly reduced midday leaf net photosynthetic rate (A) compared to evaporative cooling. Furthermore, shade net and Surround WP significantly reduced midday leaf stomatal conductance (g_s) compared to evaporative cooling and control. Evaporative cooling increased light saturated photosynthetic rate by 27 and 24% compared to shade net and Surround WP, respectively. Light compensation point and dark respiration of shaded leaves were about a third of the other treatments and about 50% less than the control leaves, respectively. Shade net down-regulated photosynthetic capacity of the leaves as evidenced by lower maximum rate of carboxylation and light saturated rate of electron transport compared to control leaves. Sunburn control treatments reduced day respiration by 60–70% compared to the control. Response of A and g_s to increasing temperature showed only slight increase in both A and g_s with increasing temperature from 20 to 30 °C. A declined at 35 °C in Surround WP and shade net leaves while it declined at 40 °C in evaporatively cooled and control leaves. Evaporative cooling and control had higher g_s than shade net and Surround WP at all leaf temperatures. In conclusion, shade net down-regulated photosynthetic reactions and Surround WP and shade net reduced leaf g_s and increased the vulnerability of leaf A and g_s to high temperature compared to evaporative cooling and control.     

Amounts of nuclear DNA in marine halophytes

The amount of nuclear DNA, expressed as the C-value, was estimated for 13 marine halophytic plant species from six families. Plant material was collected in the nature reserve of the Strunjan saltpan in the Northern Adriatic and comprised all halophytic species inside the investigated area. Reproductive region of the shoot or root tips of halophytes were dissected, nuclei were Feulgen stained and 2C-values were measured by DNA image cytometry as follows: Crithmum maritimum (4.38 pg DNA), Artemisia caerulescens (6.43 pg), Aster tripolium (21.43 pg), Inula crithmoides (3.63 pg), Atriplex portulacoides (1.83 pg), A. prostrata (1.51 pg), Salicornia europaea (2.75 pg), Salsola soda (2.62 pg), Sarcocornia fruticosa (5.91 pg), Suaeda maritima (2.11 pg), Limonium angustifolium (5.06 pg), Puccinellia palustris (8.15 pg) and Ruppia cirrhosa (4.65 pg). With the exception of the C-value estimate for A. caerulescens, which has been listed in the Plant DNA C-values Database, the C-values represent the first estimates for all the examined species. In addition, the C-value for R. cirrhosa is also the first report for the family Ruppiaceae. The investigated halophytes had a smaller genome size compared to other known C-values for species within a particular family and also when compared to the mean values of dicots and monocots. The study also showed that halophylic annuals have a smaller genome size (2.49 pg) than perennial ones (7.45 pg DNA).     

Internal conductance to CO2 transfer of adult Fagus sylvatica: Variation between sun and shade leaves and due to free-air ozone fumigation

Two separate objectives were considered in this study. We examined (1) internal conductance to CO₂ (g_i) and photosynthetic limitations in sun and shade leaves of 60-year-old Fagus sylvatica, and (2) whether free-air ozone fumigation affects g_i and photosynthetic limitations. g_i and photosynthetic limitations were estimated in situ from simultaneous measurements of gas exchange and chlorophyll fluorescence on attached sun and shade leaves of F. sylvatica. Trees were exposed to ambient air (1× O₃) and air with twice the ambient ozone concentration (2× O₃) in a free-air ozone canopy fumigation system in southern Germany (Kranzberg Forest). g_i varied between 0.12 and 0.24 mol m⁻² s⁻¹ and decreased CO₂ concentrations from intercellular spaces (C_i) to chloroplastic (C_c) by approximately 55 μmol mol⁻¹. The maximum rate of carboxylation (V_cmax) was 22–39% lower when calculated on a C_i basis compared with a C_c basis. g_i was approximately twice as large in sun leaves compared to shade leaves. Relationships among net photosynthesis, stomatal conductance and g_i were very similar in sun and shade leaves. This proportional scaling meant that neither C_i nor C_c varied between sun and shade leaves. Rates of net photosynthesis and stomatal conductance were about 25% lower in the 2× O₃ treatment compared with 1× O₃, while V_cmax was unaffected. There was no evidence that g_i was affected by ozone.     

Effects of irradiance and water flow on formation and growth of spongy and filamentous thalli of Codium fragile

Effects of irradiance and water flow on formation and growth of filamentous and spongy thalli of Codium fragile (Suringar) Hariot growing on vinylon threads were investigated at the laboratory culture. They showed clear differences in their irradiance and water flow requirements for their formation and growth. Spongy thalli were formed from the cultured filamentous thalli only at the high water flow velocity (10 cm s⁻¹). Number of the spongy thalli remarkably increased with increasing irradiance because those at 10, 50 and 100 μmol m⁻² s⁻¹ reached 0, 2 and 76 thalli m⁻¹, respectively, by 10 weeks of culture. In contrast, filamentous thalli were formed from the cultured spongy thalli at 0 and 3 cm s⁻¹, and difference in irradiance had no effect on their formation. Growth of the spongy thalli greatly accelerated under the combination of the high irradiance and high water velocity (200 μmol m⁻² s⁻¹ and 10 cm s⁻¹) because their relative growth rate in wet weight under the condition was two–four times higher than those at the other examined irradiances and water velocities. On the other hand, difference in water velocity had no effect on growth of the filamentous thalli under flowing water, and their growth decelerated at the high irradiance (200 μmol m⁻² s⁻¹). This demonstrates that water flow is a major factor controlling the formation of the spongy and filamentous thalli. The formation and growth of the spongy thalli surely occur under the combination of the high irradiance and fast flowing water. In contrast, the formation of the filamentous thalli occurs in the calm water, and their growth is inhibited under the high irradiance.     

Reproductive potential in Ruppia cirrhosa (Petagna) Grande in response to water permanence

We compared the reproductive effort of perennial and annual Ruppia cirrhosa (Petagna) Grande in a mediterranean coastal lagoon where the species develops in permanent waters as well as in shallow areas which dry up during some months. In permanently flooded areas, Ruppia cirrhosa was perennial with biomass maxima up to 800 g DW m⁻². Here, the reproductive period lasted 8–10 weeks (between April and June), the reproductive effort was low (with 4–8 fl g⁻¹ DW) and mature fruit development was practically absent. In temporarily flooded areas, in contrast, Ruppia cirrhosa developed in an annual cycle which was completed in less than 8 weeks (maximum biomass of 137 g DW m⁻²); reproductive activity began later in the year (June) and lasted 3–4 weeks, but led to more flowers (17 fl g⁻¹ DW) and a high fruit production (up to 590 fr m⁻²). We conclude that reproductive effort in Ruppia cirrhosa is highly plastic and interpret this as an adaptation to temporay flooding.     

Light acclimation of photosynthesis in three charophyte species

The main aim of this study was to investigate if the charophyte species Chara baltica, Chara canescens (two populations from the Baltic Sea (BS) and the Gulf of Korinth, Greece (GK)), and Lamprothamnium papulosum exhibit different acclimation capacities to irradiance. Growth, photosynthesis and pigment content were examined in the laboratory under six irradiance conditions (35–500 μmol photons m⁻² s⁻¹). Growth experiments showed increasing growth rates from 35 μmol photons m⁻² s⁻¹ (∼10 mg fresh weight (FW)) up to 70 μmol photons m⁻² s⁻¹ (∼20 mg FW) in C. baltica, from 35 μmol photons m⁻² s⁻¹ (∼15 mg FW) up to 380 μmol photons m⁻² s⁻¹ (∼145 mg FW) in C. canescens (BS), and up to the highest growth irradiance in algae of L. papulosum (35 μmol: ∼5 mg FW; 500 μmol: ∼20 mg FW). The species were tested for their ability to acclimate to different growth irradiances (E_g) by calculating P_max (maximum photosynthesis rate at saturating irradiances), α (the efficiency of light utilization at limiting irradiance), and E_k (the light saturation point of photosynthesis, P_max/α). All species exhibited increasing P_max with increasing E_g. Whereas both populations of C. canescens increased α with increasing E_g, L. papulosum and C. baltica did not acclimate α at all. E_k, the irradiance at which photosynthesis ceased to be light-limited, was constant for all Chara species within the range of irradiances tested. Chl a/Chl b ratios of all species were constant over the whole range of E_g. Chl a/carotenoid ratios were constant in C. baltica, whereas Chl a/carotenoid ratios in L. papulosum and C. canescens (BS) decreased from 250 and 70 μmol photons m⁻² s⁻¹ upwards, respectively. Pigmentation analysis showed that Chl a/carotenoid acclimation was mainly caused by species-specific capacity to raise the content of lutein and carotene (C. canescens (BS), C. canescens (GK)) and xanthophyll cycle pigments (XCP; L. papulosum). The non-photochemical quenching (NPQ) capacities of L. papulosum, C. canescens (BS), and C. canescens (GK) were dependent from preacclimation status of algae, whereas NPQ of C. baltica was independent from growth irradiance.Our results indicate that C. baltica and C. canescens (BS) were light saturated within the chosen irradiances, whereas C. canescens (GK) and L. papulosum did not reach their limits of high-light acclimation. The photosynthetic pigments lutein, α- and β-carotene are suggested to act as photo-protective pigments in L. papulosum and C. canescens.     

The influence of light quality on akinete formation and germination in the toxic cyanobacterium Anabaena circinalis

Physiological control of akinete formation and subsequent germination is likely to be important in understanding and predicting how natural populations of cyanobacteria respond to their environment. While previous research has indicated nutrient limitation may be important in akinete formation new results presented here indicate that in the toxic and bloom-forming species Anabaena circinalis there was a profound effect of spectral quality. Under 40 μmol photons m^?2 s^?1 photosynthetically active irradiance (PAR) of predominately red irradiance akinete production was maximal at 2.1 × 10^?4 akinetes vegetative cell^?1 d^?1, some 3000 times greater than the 6.5 × 10^?8 akinetes vegetative cell^?1 d^?1 observed under equivalent PAR but predominately blue light. For cells grown under a range of predominantly red, white and green irradiance even short exposures to blue light reduced akinete formation rates by a factor of ten relative to controls, indicating that exposure to blue light inhibits akinete formation. Germination of akinetes was not influenced by the irradiance under which akinetes were formed: 88 ± 4.1% (mean ± 1 S.D.) of akinetes germinated with no evidence of an effect on germination success due to their production under predominately red, white or green irradiance (germination of akinetes produced under blue light was not tested). Spectral quality had a significant impact on both vegetative cell and germling growth rates. The results indicate a significant reduction in the cellular differentiation of A. circinalis vegetative cells into akinetes that is mediated by blue light. In an ecological context the production of akinetes will be greater in environments with less blue light; potentially including those with slower flow, more stratification, less vertical mixing and more turbidity. The resulting spatial pattern of akinete production is likely to influence the location of akinetes in sediments and the development of subsequent blooms from excysting germlings.     

Relative growth rate,biomass partitioning and nutrient allocation in seedlings of two threatened trees grown under different light conditions

The present study investigates the variation in the relative growth, biomass and nutrient allocation in two threatened tree species viz. Magnolia punduana Hook.f. & Th. and Elaeocarpus prunifolius Wall. ex Müll. Berol. grown under three different levels of irradiance. The irradiance ranged between 1 and 12 mol m^?2 d^?1. Results showed that the highest relative growth rate (RGR) was achieved under the intermediate light treatment for both the species (mean: 0.005 mg mg^?1 d^?1). The growth response coefficient (GRC) model revealed that net assimilation rate (NAR) was the factor driving the RGR in both species. A significant positive correlation was found between NAR and RGR (R² = 0.33, p = 0.000) whereas specific leaf area (SLA) and leaf mass fraction (LMF) was negatively correlated to RGR. Overall, multiple regression of the studied species based on the independent variables viz. NAR, SLA, and LMF showed a significant relation with RGR (F(3,50,53 = 13.001, p = 0.000, R² = 0.43). The biomass distribution in the studied species is in agreement with the “balanced-growth hypothesis” where high irradiance increased allocation to below ground biomass fraction and decreased irradiance increased allocation to the above ground fraction. The highest nitrogen concentration in leaves was observed under the intermediate light treatment. Overall seedlings growth under intermediate light had a higher mean RGR indicating the species' preference for partial light conditions. Long-term experiments under varied light conditions as in the present study would provide useful insight into plant growth strategies in varied environmental conditions.     

Abrupt changes in Potamogeton and Ruppia beds in a Mediterranean lagoon

Until the early 1990s, the Ichkeul lagoon (80 km², Tunisia) was characterised by the seasonal alternation of low and high salinity and by the presence (mainly in summer and autumn) of more or less extensive Potamogeton pectinatus beds (western and south-eastern zones). The yield was largely consumed by wintering waterfowl populations (almost exclusively phytophagous), making this lagoon one of the most important wintering places in northern Africa, and recognized as a high ecological value World Heritage site. Ruppia cirrhosa (together with Chaetomorpha linum floating mats) was confined to a small north-eastern or eastern zone of the lagoon. This is the distribution which the authors observed in 1993, in the course of a study running through 1998, with P. pectinatus covering 37 km² (28,236 t DW) and 30 km² (20,139 t DW) in summer and autumn, respectively. In 1994, P. pectinatus had disappeared, an event which had already occurred in the past; however, this situation was still apparent in 1998; such a 5 year absence had never been reported since at least the early 1960s. From 1996 onwards, R. cirrhosa and C. linum “moved” to the sites formerly occupied by P. pectinatus. Direct causes (shortage of freshwater input, salinity increase) and indirect ones (construction of dams in the water catchment area of the lagoon, a relative drought) can account for these abrupt changes. The persistence of this situation could threaten the Ichkeul lagoon, as a major site for the wintering of phytophagous waterfowl.     

Antioxidant,Fusarium growth inhibition and Nasutitermes corniger repellent activities of secondary metabolites from Myracrodruon urundeuva heartwood

Myracrodruon urundeuva heartwood is resistant to biodeterioration and lectin purified from heartwood showed antifungal and termiticidal activities. This report deals with antioxidant, antifungal and termite repellent activities of secondary metabolites from M. urundeuva heartwood. Saline (SE, active hemagglutinin preparation) and methanolic (ME, without hemagglutinating activity) extracts contain phenolic compounds, gallic acid, flavonoids, luteolin, cinamic derivatives, proanthocyanidins, hydrolysable tannins, and leucoanthocyanidins. Both SE and ME showed antioxidant activity and were effective in Fusarium growth inhibition. SE was efficient against Fusarium decemcellulare, Fusarium moniliforme, Fusarium oxysporum, and Fusarium solani but it had little effect against Fusarium lateritium. ME practically had no effect on F. decemcellulare and was more active than SE against F. lateritium. SE induced mortality of Nasutitermes corniger (LC₅₀ of 1.81 mg ml^?1 for soldiers and 2.59 mg ml^?1 for workers) and had no repellent activity. ME had no termiticidal activity but was a good repellent. The detected bioactivities point out the possibility of participation of secondary metabolites in the resistance of M. urundeuva heartwood to biodeterioration. Additionally, the results indicate the use of wood residues, as extracts, a source of natural bioactive agents.     

Sex-specific light acclimation of Chara canescens (Charophyta)

Bisexual populations of the charophyte Chara canescens (Desv. et Loisel. in Loisel., 1810) containing male and female individuals are rarely found. Two experiments were carried out to study whether male and female algae from the same site exhibit different physiological capacities, especially with respect to light acclimation.Algae from two different shore levels and from laboratory cultures acclimated to six irradiance conditions (35–500 μmol photons m⁻² s⁻¹) were compared. Field measurements showed that both female and male algae of C. canescens are able to acclimate to daily changes in solar irradiance. The quantum yield of Photosystem II (PSII) decreased with increasing irradiance in the morning and increased with decreasing irradiance in the afternoon. Growth experiments showed increasing growth rates from 35 μmol photons m⁻² s⁻¹ (∼7 mg FW) up to 500 μmol photons m⁻² s⁻¹ (∼27 mg FW) in female and male C. canescens. The irradiance saturation point for photosynthesis (E_k) was about 140 μmol m⁻² s⁻¹ for both sexes within the whole range of acclimation irradiances. The maximum photosynthesis rate at saturating irradiances (P_max) of male algae was highest at E_k, whereas P_max of female algae was highest at 500 μmol photons m⁻² s⁻¹. The photosynthetic efficiency in the light-limited range (α) increased in female C. canescens and decreased in male C. canescens. The ratio of the non-photochemical quenching parameter (NPQ) to the relative electron transport rates rETR_(MT) increased in both sexes with irradiance, but showed a steeper increase in male than in female algae. Pigment analysis showed similar acclimation pattern for male and female C. canescens. Chl a/Chl b ratios of both sexes were constant over the whole range of E_g, whereas Chl a/carotenoid ratios in male and female C. canescens decreased from 70 μmol photons m⁻² s⁻¹ upwards. Pigment analysis pointed out that the carotenes α-, β- and γ-carotene were more prominent in male than in female algae.Our results indicate that female C. canescens are more efficient in light acclimation than male algae from the same site. Nevertheless, further investigations of bisexual C. canescens populations resolving CO₂-uptake mechanisms and/or genetic differences are needed.     

Comparative diel oxygen cycles preceding and during a Karenia bloom in Sarasota Bay,Florida, USA

The diel change in dissolved oxygen concentrations were recorded with an automated incubator containing a pulsed oxygen sensor in Sarasota Bay, Florida. The deployments occurred during a ‘pre-bloom’ period in May to June 2006, and during a harmful algal bloom dominated by Karenia brevis in September 2006. The diurnal (daylight) increase in dissolved oxygen concentrations varied from 16 to 104 μmol O₂ l⁻¹ with the corresponding nocturnal decrease in oxygen varying from 16 to 77 μmol O₂ l⁻¹. Nocturnal respiration consumed 42–113% of the diurnal net oxygen production with the minimum and maximum during the pre-bloom period. Hourly production rates closely followed fluctuations in irradiance with maximum rates in the late morning. Hourly oxygen utilization rates (community respiration) at night were highest during the first few hours after sunset.     

Benefits of clonal integration between interconnected ramets of Vallisneria spiralis in heterogeneous light environments

Interconnected ramets of the submersed macrophyte Vallisneria spiralis were subjected to two homogeneous treatments (shading or not shading whole plants) and two heterogeneous treatments (only shading basal or apical ramets of plants). The benefits and costs of clonal integration between connected ramets grown in heterogeneous treatments were examined. Results showed that shading apical ramets induced significant benefits to the performance of whole plant in terms of dry weight per plant (P < 0.01) and number of ramets per plant (P < 0.05). Especially for the unshaded basal ramets, their dry weight, number of ramets, number of branches and total stolon length were 89%, 30%, 29% and 58% higher than the corresponding ramets in homogeneous treatment, respectively. Compared to their controls in homogeneous treatments, unshaded basal ramets produced more leaf mass (0.15 g versus 0.11 g) whereas shaded apical ramets produced more root mass (0.012 g versus 0.008 g). However, there was a different pattern of integration when basal ramets were shaded. Shading basal ramets led to a significant decrease in stolon growth, but the individual performance of shaded ramets improved. Cost-benefit analyses revealed that dry weight per ramet of basal shaded ramets was 31% greater than that of basal shaded ramets in the homogeneous treatment. We can conclude that V. spiralis can benefit from clonal integration in heterogeneous light environments, but that the scale of these benefits is related to the quality of light environments where the clone become established.     

Mitochondrial distribution patterns in canine oocytes as related to the reproductive cycle stage

This study investigates the mitochondrial (mt) distribution in canine ovarian oocytes examined at recovery time, as related to the reproductive cycle stage, and in oviductal oocytes. Ovarian Germinal Vesicle (GV) stage oocytes were recovered from bitches in anestrous (A, n = 2), follicular phase (F, n = 4), ovulation (O, n = 2), early luteal (EL, n = 7) and mid/late luteal phase (MLL, n = 2). Oviductal GV, metaphase I (MI) or MII stage oocytes were recovered from six bitches between 56 and 110 h after ovulation. Mitochondria were revealed by using MitoTracker Orange CMTM Ros and confocal microscopy. In ovarian oocytes, three mt distribution patterns were found: (I) small aggregates diffused throughout the cytoplasm; (II) diffused tubular networks; (III) pericortical tubular networks. Significantly higher rates of oocytes showing heterogeneous mt patterns (II + III) were obtained from bitches in F (75%) and in O (96%) compared with bitches in A (31%; F vs. A: P < 0.05; O vs. A: P < 0.001), in EL (61%; O vs. EL: P < 0.01), or in MLL (0%; F vs. MLL: P < 0.05; O vs. MLL: P < 0.001). Fluorescence intensity did not vary according to mt distribution pattern except that it was lower in oocytes recovered in EL phase and showing small mt aggregations (P < 0.001). The majority of ovulated MII stage oocytes (79%) showed diffused tubular mt network. We conclude that mt distribution pattern of canine ovarian immature oocytes changes in relation to reproductive cycle stage and that patterns observed in oocytes recovered from bitches in periovulatory phases are heterogeneous and similar to those of in vivo matured oocytes.     

Cord blood nesfatin-1 in large for gestational age pregnancies

ObjectiveTo investigate possible alterations in cord blood levels of adipokine nesfatin-1 (secreted by adipose tissue and pancreatic β-cells and implicated in glucose metabolism and insulin resistance), as well as insulin, in large (LGA) and appropriate for gestational age (AGA) pregnancies, granted that these groups differ in body fat mass and metabolic/endocrine mechanisms.Materials and methodsCord blood nesfatin-1 and insulin concentrations were prospectively measured in 40 LGA (9 born from diabetic and 31 from non-diabetic mothers) and 20 AGA singleton full-term infants as well as their mothers.ResultsCord blood nesfatin-1 concentrations were significantly lower in LGA compared to AGA neonates (b = ?0.206, SE 0.07, p = 0.005). However, cord blood nesfatin-1 concentrations were elevated in infants born from mothers with gestational diabetes mellitus (GDM), compared to those born from non-diabetic mothers, after controlling for group (b = 0.190, SE 0.10, p = 0.05). Finally, cord blood nesfatin-1 concentrations were lower in cases of vaginal delivery (b = 0.11, SE 0.05, p = 0.042). Insulin levels were significantly elevated, as customized centiles increased (b = 0.004, SE = 0.002, p = 0.016). No significant correlation was found between insulin and nesfatin-1 in maternal and umbilical cord levels.ConclusionsIn this study nesfatin-1 levels are decreased in LGA compared to AGA fetuses. Fetal nesfatin-1 concentrations are higher in cases of GDM and cord blood nesfatin-1 concentrations are lower in cases of vaginal delivery.     

Influence of climatic conditions and industrial emissions on spruce tree-ring Pb isotopes analyzed at ppb concentrations in the Athabasca oil sands region

This study investigates Pb isotope ratios at low concentrations (parts per billion; ppb) in tree rings and soils in the Northern Athabasca Oil Sands Region (NAOSR), western Canada, to evaluate if: (1) climatic conditions influence on tree-ring Pb assimilation; and (2) such low Pb content allows inferring the regional Pb depositional history.Our results reflect the influence of winter snow cover and the importance of minimum temperature and precipitation in spring and summer on the bioavailability of Pb and its passive assimilation by trees in sub-arctic semi-humid climatic conditions. Winter conditions can influence the state of root systems that subsequently impacts the following growth period, while spring and summer conditions likely control microbial processes and water source, and may thus impact Pb assimilation by trees. Thus, the results of tree-ring Pb concentrations show interesting correlation with cumulated snow from November of the previous year to February (ρ = 0.53; P < 0.01; n = 36). Likewise, the ²⁰⁶Pb/²⁰⁷Pb ratios inversely correlate with minimum temperature from April to September (ρ = −0.67; P < 0.01; n = 40) and precipitation from May to August (ρ = −0.42; P < 0.01; n = 36). The isotopic results also suggest that the effects of climatic variations are superimposed by regional industrial Pb deposition: Western North American Aerosols (WNAA) and fugitive dust from the oil sands mining operations appear to be the most likely sources.Importantly, this study suggests that even at low Pb concentrations, tree-ring Pb isotopes are modulated by climatic conditions and potential input of regional and long-range transport of airborne Pb. These interpretations open the possibility of using Pb isotopes as an environmental tool for inferring the pollution history in remote regions, and improving our understanding of its natural cycle through the forest environment.     

Shade tree cover criteria for non-point source pollution control in the Rainforest Alliance coffee certification program: A snapshot assessment of Costa Rica's Tarrazú coffee region

Management of non-point source pollution is of great importance in the context of coffee agriculture, as this land use often coincides with headwater streams that influence water quality at the basin scale. Sustainability certification programs, such as the Rainforest Alliance (RA), provide management guidelines that promote non-point source pollution control in coffee. One of these practices is the maintenance of shade trees within farms, required by RA at a minimum of 40% shade tree cover. Here we assess the effectiveness of this practice in Tarrazú, a high elevation coffee growing region in Costa Rica. We monitored indicators of non-point source pollution in streams with both high and low shade tree cover. Streams with High Shade Tree Cover (HSTC, N = 5 subwatersheds) had 35–55% cover, approximating or exceeding the RA recommendation of at least 40%; and streams with Low Shade Tree Cover (LSTC, N = 5 subwatersheds), had 18–31% cover. We monitored the ten study streams during the dry (April & December), transition (July), and peak (October) rainfall seasons of 2013, and compared responses using t-tests. We found support for the effectiveness of shade tree cover in controlling non-point source pollution: HSTC streams had significantly (p = 0.042) lower mean annual turbidity and significantly (p = 0.004) lower turbidity during the transition season. HSTC streams also had significantly (p = 0.05) lower conductivity values during the transition period, although this trend was weaker through the year. Subwatersheds with HSTC streams were characterized by a higher percentage of RA-certified coffee than LSTC streams. Our study provides evidence of the benefits of RA shade tree cover criteria for managing water quality within high elevation tropical agro-ecosystems, especially if implemented at the watershed scale. These results contribute to our understanding of the role of agroforestry certification on tropical ecosystem conservation, and are the first account of the effectiveness of a specific coffee certification guideline on non-point source pollution control.