scholarly journals Seasonal dynamics of Daphnia laevisBirge, 1878 ephippia in a tropical lake with a description of a new methodology for in situ evaluation

2014 ◽  
Vol 74 (3) ◽  
pp. 642-648 ◽  
Author(s):  
LPM Brandão ◽  
DGF Pujoni ◽  
PM Maia-Barbosa
Keyword(s):  
Water Column ◽  
Seasonal Dynamics ◽  
Thermal Stratification ◽  
Core Sample ◽  
Hatching Rate ◽  
The Core ◽  
Significant Difference ◽  
Chi Squared ◽  
Hatching Rates

The effect of dormancy in zooplankton populations is still unknown, largely because of the lack of methods to estimate hatching and production of the dormant stages. This study aimed to compare the production and hatching rates of ephippia of Daphnia laevis between thermal stratification and mixing periods in Jacaré Lake (Middle Rio Doce, Minas Gerais, Brazil). For this, we collected ephippia on the sediment with core sampler and we created a device called the “Ephippial Collector”. There was a significant difference in ephippia hatching in situ between stratification and mixing periods (Pearson's Chi-squared test p <0.001), being higher in the second one. Significant differences in the hatching rates between periods was observed in the laboratory only for ephippia collected with Ephippial Collectors (Pearson's Chi-squared test p <0.001), being higher during the mixing period (∼8%). The core sample allows the collection of a certain fraction of the sediment that may contain a mixture of ephippia produced in different periods, i.e., may contain old and not viable ephippia, which masks the hatching rate. Thus, seasonality in hatching rates of ephippia was reported only by Ephippial Collectors. The higher hatching rate observed during the mixing period in the lake suggests that individuals hatched from ephippia may contribute to the increase in the population of D. laevis in the water column at this time.

Phosphate diagenesis of carbonate sediments as a mode of in situ formation of marine phosphorites: Observations in a core from the eastern Pacific

1968 ◽  
Vol 5 (1) ◽  
pp. 81-87 ◽  
Author(s):  
Bruno F. d'Anglejan
Keyword(s):  
Core Sample ◽  
Ion Concentration ◽  
Soluble Phosphate ◽  
Carbonate Sediments ◽  
The Core ◽  
Carbonate Ion ◽  
Carbonate Fluorapatite ◽  
In Situ Formation ◽  
Common Association

Carbonate-fluorapatite, the mineral of marine phosphorite, is found to form contemporaneously within the sediments by the replacement of skeletal carbonate in a core sample of foraminiferal ooze from the eastern tropical Pacific. A systematic downward increase in apatite within the core suggests that replacement is continuing at a decreasing rate in the sediments. The widespread distribution of foraminiferal ooze on the California borderland and its common association with phosphorite suggest that this material may play a role in the phosphorite accumulation there. The reaction of CaCO3 with soluble phosphate in conditions favoring the slow dissolution of the carbonate mineral may result within the sediments in an increase of the carbonate ion concentration, which appears to control the rate of replacement.

47 COMPARISON BETWEEN CRYOLOOP AND OPEN PULLED STRAW VITRIFICATION METHODS FOR BOS INDICUS BLASTOCYSTS

2014 ◽  
Vol 26 (1) ◽  
pp. 137 ◽  
Author(s):  
E. Herrera-Puerta ◽  
N. Chavarria ◽  
R. Urrego ◽  
N. Rodriguez-Osorio
Keyword(s):  
Large Scale ◽  
High Efficiency ◽  
Mammalian Species ◽  
Bos Indicus ◽  
Commercial Application ◽  
Hatching Rate ◽  
Cooling Rates ◽  
Wide Range ◽  
Significant Difference ◽  
Hatching Rates

A major obstacle of large-scale commercial application of bovine in vitro fertilization is the lack of a suitable cryopreservation method for supernumerary embryos produced. The traditional slow-freezing method has proven to be effective for embryos of a wide range of mammalian species; however, the formation of intracellular ice is still a challenge and the efficiency needs to be improved. Over the past decade, several advances have taken place in vitrification technologies, such that it can provide high efficiency with better pregnancy outcome due to its high cooling rates and the lack of crystals formed inside the cells. Most vitrification methods have been evaluated in Bos taurus cattle but more still remains to be investigated in Bos indicus races predominant in the tropics. There are several vitrification protocols and holders, including CryoLoop, open pulled straw (OPS), MS Grids, and Cryotop, among others. The CryoLoop method uses a nylon loop attached to a metal Cryovial lid were blastocysts are placed on an equilibration solution film. CryoLoop cooling rates are approximately 20.000°C min–1 and have shown very good results in humans. The OPS is a well-known support for bovine blastocysts; the embryos are taken by capillarity into the OPS and use a 1- to 2-μL drop of final equilibration solution. Cooling rates using this method are approximately 2.000°C min–1. The aim of this work was to prove CryoLoop and OPS vitrification methods in Bos indicus blastocyst and compare re-expansion and hatching rates 24 h after warming. Ovaries were collected from a local slaughterhouse and cumulus-oocyte complexes (COC) were treated for the standard IVF method. A total of 60 blastocysts were vitrified in CryoLoops and 68 blastocysts in OPS (within 4 repeats). For CryoLoops, groups of 2 blastocysts were placed in a solution of 7.5% ethylene glycol (EG) and 7.5% dimethyl sulfoxide (DMSO) for 3 min, and then were placed in a solution of 15% EG, 15% DMSO, 10 mg mL–1 of Ficoll 70, and 0.65 M sucrose for 20 s, and rapidly were put into the nylon loop and taken to the LN. For OPS, groups of 2 to 3 blastocysts were placed in a solution of 10% EG and 10% DMSO for 1 min, and then were placed in a solution of 20% EG and 20% DMSO for 20 s, and rapidly were taken by capillarity into the OPS and taken to the LN. Thawing was the same for both treatments; vitrified blastocysts were taken out from the LN and rapidly put into a solution of 0.3 M sucrose for 2 min and then put into a solution of 0.2 M sucrose for 3 min, were washed twice in TCM199 supplemented with 10% FCS, and cultured for 24 h in CR1aa media. Data were analysed using the R language. Media comparison for proportions was done using a chi-squared test. No significant difference was observed in re-expansion or hatching rates between CryoLoop and OPS supports (P = 0.01 for both); however, the CryoLoop method showed more efficiency than OPS in re-expansion rate (65 v. 44.4%, respectively) and hatching rate (30.8 v. 20%, respectively). In all cases, the CryoLoop method showed much better outcomes. The results indicate that vitrification in CryoLoops is a suitable method for cryopreservation of Bos indicus blastocysts.

Did an earthquake located off Jersey trigger a mudflow preserving the only loess outcrop known under the seas?

2020 ◽  
Vol 177 (5) ◽  
pp. 911-922
Author(s):  
Jean-Pierre Lefort ◽  
Paul Chambers ◽  
Guzel Danukalova ◽  
Jean-Laurent Monnier ◽  
Eugenia Osipova ◽  
...  
Keyword(s):  
Slope Failure ◽  
Core Sample ◽  
Seismic Zone ◽  
Content Type ◽  
The Core ◽  
Loess Deposit ◽  
Mollusc Species ◽  
Supplementary Material ◽  
Rule Out

A 5 m long core sample, retrieved from between Jersey and the Cotentin (France) has been studied using different techniques. Between the lower part and the top, the core is a yellowish loess, a black mud and a grey shelly formation. The basal formation, which displays a typical loess granulometry, is the only loess found anywhere in situ on the subtidal seabed worldwide. Elsewhere, this fragile sediment has always been washed out by the successive Quaternary transgressions. The overlying mud formation, which displays characteristics of a landslide, sealed the loess deposit. Because this core has been sampled on the rim of a submarine valley located in front of a major onshore geological disruption, clearly associated with an active seismic zone, it is possible that an earthquake triggered a slope failure causing a gravity collapse of materials that protected the loess deposit from subsequent erosion, although we cannot completely rule out the effects of a large flood.Supplementary material: Tables showing the results of the pollen analysis and distribution of mollusc shells and other fossils in borehole O-VC15, and a figure showing the distribution of mollusc species in core O-VC15 and a possible reconstruction of the palaeoenvironment during sediment deposition are available at https://doi.org/10.6084/m9.figshare.c.4991753

scholarly journals Bioturbation, ecosystem functioning and community structure

2002 ◽  
Vol 6 (6) ◽  
pp. 999-1005 ◽  
Author(s):  
C. L. Biles ◽  
D. M. Paterson ◽  
R. B. Ford ◽  
M. Solan ◽  
D. G. Raffaelli
Keyword(s):  
Community Structure ◽  
Water Column ◽  
Ecosystem Functioning ◽  
Nutrient Concentration ◽  
Nutrient Release ◽  
Nutrient Concentrations ◽  
Infaunal Community ◽  
Significant Difference ◽  
In Situ Experiments

Abstract. The effect of community structure on the functioning of the ecosystem is an important issue in ecology due to continuing global species loss. The influence of infaunal community structure on the functioning of marine systems is proposed here to act primarily through bioturbation of the sediment. Nutrient concentration in the water column, generated by release from the sediment, was used as a measure of ecosystem functioning. In situ and laboratory experiments showed a significant difference in nutrient concentrations with different species treatments. Bioturbation profiles showing the incorporation of tracer particles also differed between communities with different dominant species. The behavioural differences between infaunal species, generating different modes and rates of bioturbation, are therefore proposed to influence nutrient release. The presence and quantity of bioturbating infauna also influenced the amount of sediment suspended in the water column. The increase in surface area available for microbial activity may generate an increase in nutrient cycling. Abiotic influences on sediment structure, such as flow, may have a similar effect on nutrient concentration. Annular flumes used in both laboratory and in situ experiments to generate flow conditions produced a significant increase in ammonia (NH4-N) production in macrofaunal treatments. Flow may influence the behaviour of macrofaunal species, causing changes in NH4-N production through modifying bioturbation of the sediment. Keywords: bioturbation, community structure, ccosystem functioning, estuaries, flow, infauna

A STUDY OF THE SOIL FAUNA IN A MATURE STAND OF RED SPRUCE (PICEA RUBENS) IN THE UNIVERSITY OF NEW BRUNSWICK FOREST

1972 ◽  
Vol 104 (11) ◽  
pp. 1801-1804 ◽  
Author(s):  
T. D. Smith ◽  
N. R. Brown ◽  
N. E. Carter
Keyword(s):  
Soil Fauna ◽  
Core Sample ◽  
Sampling Procedure ◽  
Picea Rubens ◽  
Red Spruce ◽  
Tree Crowns ◽  
The Core ◽  
Mature Stand ◽  
Significant Difference ◽  
The University

AbstractThis investigation was concerned with fauna above and within the litter, fermentation, and humus layers of the soil in a mature stand of red spruce (Picea rubens Sarg.). The following six microsites were designated for sampling: "open" and "closed" hollows, flats, and hummocks. "Open" and "closed" referred to the space among the tree crowns directly above the microsites. Three sampling techniques, namely core samplers, pitfalls and Tullgren funnels, were employed. Samples were collected weekly from spring to winter in 1966 and 1967 by all methods except that in 1966 Tullgren funnel samples were collectell biweekly. Collected fauna comprised five Phyla, 11 classes, 28 orders, and approximately 124 families. The transformed core sample and Tullgren funnel data were analyzed using an ANOVA (2-way classification) procedure. Transformed pitfall data required an ANOVA (2-way classification, with sampling) procedure. The core sample and Tullgren funnel methods indicated a significant difference (α = 0.10) among microsites based on total weekly (or biweekly) faunal catches in all but one case (which approached significance). In 1966 there were no significant differences (α = 0.10) among the pitfall microsites but in 1967 there were. In all cases there were significant differences (α = 0.10) in the total weekly or biweekly catches of fauna from the various microsites.

54 CRYOPRESERVATION OF BOVINE IN VITRO-PRODUCED EMBRYOS: INTRINSIC FACTORS DETERMINING VITRIFICATION OUTCOMES

2015 ◽  
Vol 27 (1) ◽  
pp. 120
Author(s):  
M. N. Saucedo ◽  
M. Kurome ◽  
M. Reichenbach ◽  
E. Wolf ◽  
H.-D. Reichenbach
Keyword(s):  
Survival Rates ◽  
Hollow Fibre ◽  
Hatching Rate ◽  
Bovine Embryo ◽  
Total N ◽  
Intrinsic Factors ◽  
Significant Difference ◽  
Embryo Stage ◽  
Hatching Rates

As a part of a study on bovine embryo genomic evaluation, effects of an intact (iZP) or opened zonae pellucidae (oZP) of in vitro-produced embryos on vitrification outcomes were assessed. In the first experiment, only iZP embryos were subjected to vitrification, using either the hollow fibre vitrification method (HFV; Matsunari et al. 2012 J. Reprod. Dev.) or the cryologic vitrification method (CVM; CryoLogic®, Blackburn, Victoria, Australia). Developmental stage (morula = M; early blastocyst = EaB; blastocyst = B) and quality (good = 1; fair = 2) before vitrification were evaluated. In a first set of experiments, quality 1 and 2 iZP embryos were vitrified either by the HFV or the CVM method. A significant difference between the 2 methods was found when comparing overall survival rates (24–48 h post-thaw; HFV 59.32% v. CVM 78.9%; P < 0.001; unpaired t-test, GraphPad Prism, GraphPad Software Inc., La Jolla, CA, USA). Concerning hatching rates, no significant difference was found (HFV 48.7% v. CVM 57.8%; P > 0.1). In order to evaluate influence of embryo stage and quality on HFV or CVM outcomes, iZP embryos vitrified by the HFV method were classified regarding quality (1: n = 207; 2: n = 66; total n = 273) and embryo stage (M: n = 78; EaB: n = 74; B: n = 121). Concerning survival rates, no significant difference was found between M 1 (57.4%) and M 2 (44.6%), or EaB 1 (80%) and EaB 2 (68%). However, a significant difference was found when comparing B 1 (77%) and B 2 (29%; P < 0.05). With regard to hatching rate, no significant difference was found between M 1 (39.9%) and M 2 (30%), or EaB 1 (66.6%) and EaB 2 (57%). However, significant difference was found between B 1 (60.9%) and B 2 (22%; P < 0.05). With regard to the CVM (1: n = 172; 2: n = 82; total n = 254), no significant difference was found when analysing survival rates of EaB 1 (82%) and EaB 2 (80%), or B 1 (87%) and B 2 (74%), whereas the survival rates were significantly different between M 1 (80%) and M 2 (53%; P < 0.05). Significant differences regarding hatching rates were not found between M 1 (51%) and M 2 (28%) or EaB 1 (55%) and EaB 2 (65%), whereas the hatching rate of B 1 (76%) was not significantly higher than that of B 2 (48.8%; P < 0.05). In a second set of experiments, oZP EaB (1: n = 14) and oZP B (1: n = 30) were vitrified by the CVM method. No significant difference regarding survival rates concerning stage (95 and 72%, EaB and B, respectively), or between treatments (EaB iZP v. oZP, and B iZP v. oZP; P > 0.1) was found. Effect of ZP, either intact or opened, does not seem to affect survival rates (judged by their re-expansion 24–48 h post-thaw) of good-quality embryos.The authors thank the Bavarian Research Foundation for the financial support (AZ-1031-1; DOK-153-12).

Risk of venous thromboembolism following surgical treatment of superficial venous incompetence

VASA ◽  
2017 ◽  
Vol 46 (6) ◽  
pp. 484-489 ◽  
Author(s):  
Tom Barker ◽  
Felicity Evison ◽  
Ruth Benson ◽  
Alok Tiwari
Keyword(s):  
Venous Thromboembolism ◽  
Varicose Vein ◽  
Lower Incidence ◽  
Varicose Veins ◽  
Secondary Data ◽  
Foam Sclerotherapy ◽  
Increased Risk ◽  
Significant Difference ◽  
Chi Squared ◽  
One Year

Abstract. Background: The invasive management of varicose veins has a known risk of post-operative deep venous thrombosis and subsequent pulmonary embolism. The aim of this study was to evaluate absolute and relative risk of venous thromboembolism (VTE) following commonly used varicose vein procedures. Patients and methods: A retrospective analysis of secondary data using Hospital Episode Statistics database was performed for all varicose vein procedures performed between 2003 and 2013 and all readmissions for VTE in the same patients within 30 days, 90 days, and one year. Comparison of the incidence of VTEs between procedures was performed using a Pearson’s Chi-squared test. Results: In total, 261,169 varicose vein procedures were performed during the period studied. There were 686 VTEs recorded at 30 days (0.26 % incidence), 884 at 90 days (0.34 % incidence), and 1,246 at one year (0.48 % incidence). The VTE incidence for different procedures was between 0.15–0.35 % at 30 days, 0.26–0.50 % at 90 days, and 0.46–0.58 % at one year. At 30 days there was a significantly lower incidence of VTEs for foam sclerotherapy compared to other procedures (p = 0.01). There was no difference in VTE incidence between procedures at 90 days (p = 0.13) or one year (p = 0.16). Conclusions: Patients undergoing varicose vein procedures have a small but appreciable increased risk of VTE compared to the general population, with the effect persisting at one year. Foam sclerotherapy had a lower incidence of VTE compared to other procedures at 30 days, but this effect did not persist at 90 days or at one year. There was no other significant difference in the incidence of VTE between open, endovenous, and foam sclerotherapy treatments.

Incubation Temperature Influences the Duration of Egg Hatching and Early Development in the Boreal Digging Frog, Kaloula Borealis

2020 ◽  
Vol 3 (1) ◽  
pp. ACCEPTED
Author(s):  
Rho-Jeong Rae
Keyword(s):  
Water Temperature ◽  
Early Life ◽  
Rainy Season ◽  
Incubation Temperature ◽  
Life Stages ◽  
Early Life Stages ◽  
Egg Hatching ◽  
Significant Difference ◽  
The Mean ◽  
Hatching Rates

This study investigated the boreal digging frog, Kaloula borealis, to determine the egg hatching period and whether the hatching period is affected by incubation temperature. The results of this study showed that all the eggs hatched within 48 h after spawning, with 28.1% (±10.8, n=52) hatching within 24 h and 99.9% (±0.23, n=49) within 48 h after spawning. A significant difference was noted in the mean hatching proportion of tadpoles at different water temperatures. The mean hatching rates between 15 and 24 h after spawning was higher at a water temperature of 21.1 (±0.2) °C than at 24.1 (±0.2) °C. These results suggest that incubation temperature affected the early life stages of the boreal digging frog, since they spawn in ponds or puddles that form during the rainy season.

The Carbon:²³⁴Thorium ratios of sinking particles in the California Current Ecosystem 2: Examination of a thorium sorption, desorption, and particle transport model

2019 ◽  
Author(s):  
Michael Stukel ◽  
Thomas Kelly
Keyword(s):  
Organic Carbon ◽  
Water Column ◽  
Particulate Organic Carbon ◽  
Transport Model ◽  
California Current ◽  
In Situ Measurements ◽  
Power Law Distribution ◽  
Sinking Particles ◽  
Organic Carbon Concentration

Thorium-234 (234Th) is a powerful tracer of particle dynamics and the biological pump in the surface ocean; however, variability in carbon:thorium ratios of sinking particles adds substantial uncertainty to estimates of organic carbon export. We coupled a mechanistic thorium sorption and desorption model to a one-dimensional particle sinking model that uses realistic particle settling velocity spectra. The model generates estimates of 238U-234Th disequilibrium, particulate organic carbon concentration, and the C:234Th ratio of sinking particles, which are then compared to in situ measurements from quasi-Lagrangian studies conducted on six cruises in the California Current Ecosystem. Broad patterns observed in in situ measurements, including decreasing C:234Th ratios with depth and a strong correlation between sinking C:234Th and the ratio of vertically-integrated particulate organic carbon (POC) to vertically-integrated total water column 234Th, were accurately recovered by models assuming either a power law distribution of sinking speeds or a double log normal distribution of sinking speeds. Simulations suggested that the observed decrease in C:234Th with depth may be driven by preferential remineralization of carbon by particle-attached microbes. However, an alternate model structure featuring complete consumption and/or disaggregation of particles by mesozooplankton (e.g. no preferential remineralization of carbon) was also able to simulate decreasing C:234Th with depth (although the decrease was weaker), driven by 234Th adsorption onto slowly sinking particles. Model results also suggest that during bloom decays C:234Th ratios of sinking particles should be higher than expected (based on contemporaneous water column POC), because high settling velocities minimize carbon remineralization during sinking.

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