Embryonic Development and a Simple Method for the Evaluation of Developmental Competence in Murray Cod (Maccullochella peelii) Eggs

Early ontogeny-related changes of the fatty acid composition in the Percichthyid fishes trout cod, Maccullochella macquariensis and Murray cod, M. peelii peelii

The amino acid profiles in developing eggs and larvae of the freshwater Percichthyid fishes, trout cod, Maccullochella macquariensis and Murray cod, Maccullochella peelii peelii

The problem discussed in the article refers to a wider context of the empirical research realized within the doctoral dissertation. The research aims at proving the influence of the educational evaluation of the intercultural competence on the development of personal communicative competence of the first year students of French in the College of Foreign Language at the University of Adam Mickiewicz. The evaluation of the competence was conducted in the institutional conditions with the use of traditional media materials in French and Polish. The article introduces the concept of the educational evaluation of intercultural competence. The author also presents the results of the empirical research from its initial phase. The main focus is on the issue of students' metacognitive readiness to perform this type of evaluation. The article aims to show that the positive role of the educational evaluation of intercultural competence in developing personal communicative competence of learners depends to a large extent on the level of metacognitive awareness they managed to reach.

Effects of PUFA-enriched Artemia on the early growth and fatty acid composition of Murray cod larvae

Simple SummaryEuropean dairy cows are extremely sensitive to heat stress. During hot summers milk yield is suppressed, welfare status of the cows is aggravated, and their fertility is seriously compromised. The observed subfertility is attributed to endocrinological alterations and mainly to inability of the early embryo to develop uneventfully until the implantation stages. To protect the integrity and the functionality of their cells, all mammals have inherent defense mechanisms against external insults. A major representative of these molecules are the heat shock proteins (HSPs) that are secreted by almost all cells. In this study, we examined the effects of exogenous HSP70 on the developmental competence and quality of early embryos produced in vitro, after 24-h exposure to slightly elevated temperature. Our findings imply that the temperature rise is detrimental for the developmental potential of the early embryos, and that the HSP70 can partly mitigate the harmful effects of heat stress, by improving the embryo yield and by reducing the adverse effects of heat stress on some embryo quality characteristics.The aims of the present study were to examine the effects of HSP70 addition in the in vitro culture medium of day 3 embryos on their developmental competence and quality. Bovine oocytes (n = 1442) were in vitro matured, inseminated and cultured for the first two days according to standardized methods. The presumptive zygotes were randomly allocated in three experimental groups: Control, C (embryos cultured at 39 °C throughout the culture period), group C41 (temperature was raised to 41 °C from the 48th to 72nd h post insemination (p.i.) and then it returned at 39 °C for the remaining culture period), and group H41 (the temperature modification was the same as in C41 and during heat exposure, HSP70 was added in the culture medium). Cleavage and embryo yield were assessed 48 h p.i. and on days 7, 8, 9, respectively and gene expression in day 7 blastocysts was assessed by RT-PCR. Blastocyst yield was the highest in group C39; and higher in group H41 compared to group C41. From the gene expression analyses, altered expression of 11 genes was detected among groups. The analysis of the orchestrated patterns of gene expression differed between groups. The results of this study confirm the devastating effects of heat stress on embryo development and provide evidence that HSP70 addition at the critical stages can partly counterbalance, without neutralizing, the negative effects of the heat insult on embryos, acting mainly through mechanisms related to energy deployment.

In the Gulf of St. Lawrence, Canada, productivity-determining biophysical interactions occur in the upper 0 to 30 m of the water column. The eggs and larvae of several commercially important marine invertebrates and fishes (e.g. Gadus morhua L.) are found in this layer. Measurements of the diffuse attenuation coefficients for ultraviolet-B radiation (280 to 320 nm, UV-B) at various locations in this geographic region indicated maximum 10% depths (the depth to which 10% of the surface energy penetrates at a given wavelength) of 3 to 4 m at a wavelength of 310 nm. This represents a significant percentage of the summer mixed-layer water column: organisms residing in this layer are exposed to UV-B radiation. Laboratory experiments using a Xenon-arc-lamp based solar simulator revealed that cod embryos exposed to UV-B exhibited high wavelength-dependent mortality. The strongest effects occurred under exposures to wavelengths below 312 nm. This susceptibility was also dependent upon developmental stage; mortality was particularly high during gastrulation. At the shorter wavelengths (<305 nm) UV-B-induced mortality was strongly dose-dependent, and not significantly influenced by dose-rate. The biological weighting function (BWF) derived for UV-B-induced mortality in cod eggs is similar to that reported for naked DNA – suggesting that the mortality is a direct result of DNA damage. There was no evidence of a detrimental effect of ultraviolet-A radiation (320 to 400 nm). Calculations based upon the BWF indicate that, under current noon surface irradiance, 50% of cod eggs located at or very near (within 10 cm) the ocean surface will be dead after 42 h of exposure. Under solar spectral irradiance simulating a 20% decrease in ozone layer thickness, this time drops to 32 h. These are first-order estimates based upon surface irradiance taken at a time of day during which the values would be maximal. Nonetheless, they illustrate the relative changes in UV-B impacts that will result from ozone layer depletions expected over the coming decades. It is also important to point out that variability in cloud cover, water quality, and vertical distribution and displacement of cod eggs and larvae within the mixed layer, can all have a greater effect on the flux of UV-B radiation to which fish eggs are exposed than will ozone layer depletion at these latitudes.

What is the relationship between the metabolism of preimplantation embryos and their developmental competence?

The release of cold-water from hypolimnetic zones of impoundments sharply reduces downstream riverine water temperature. This cold-water pollution (CWP) can extend for hundreds of kilometres, severely challenging the physiological ability of aquatic fauna, particularly ectotherms such as fish, to maintain essential processes such as metabolism, development and growth and survival. The impact of CWP on native fish, especially early life stages, is poorly known. We investigated the effect of a 24-hour exposure to a range of environmentally-related water temperatures (8, 10, 12, 14, 16, 18 and 20°C) on three age-classes (&lt;24-hour-old, 7-day and 14-day-old larvae) of two Australian native fish species: Murray cod (Maccullochella peelii) and Macquarie perch (Macquaria australasica). Overall, larvae of M. peelii were more sensitive to lower water temperatures and hence CWP than M. australasica, indicated by higher rates of equilibrium loss. Larvae of M. peelii were most sensitive to exposure at seven days old whereas M. australasica larvae were most sensitive at &lt;24-h-old. Using our results, we modelled pre- and post-impoundment temperature scenarios and estimated the downstream CWP footprint for both species in an Australian river reach. Larvae of M. peelii were predicted to be absent from the first 26 km of river downstream of the impoundment compared with no impact on the distribution of M. australasica. Managing riverine water temperature below impoundments is fundamental to promoting positive outcomes for endemic fish on not only a local, but global basis. This study emphasises the differential impact of CWP among the critical early life stages and fish species and highlights the urgent need to better manage hypolimnetic water releases to improve downstream river ecosystems.

Temperature is essential to the maintenance of optimal physiological functioning in aquatic organisms. Fish can manage natural fluctuations in temperature; however, in freshwater ecosystems acute and rapid temperature changes can originate from sources such as large dams and industrial effluents. These rapid temperature changes may induce several physiological and behavioural responses that can result in lethal and sub-lethal consequences. The present study assessed immediate sub-lethal and short-term (10days) lethal responses of three species of Australian freshwater fish larvae and early-stage juveniles to a range of different 'field-relevant' cold shocks (-4, -6, -8 and -10°C). Murray cod (Maccullochella peelii), silver perch (Bidyanus bidyanus) and golden perch (Macquaria ambigua) were tested at two age groups to elucidate the interaction between ontogeny and sensitivity to cold shock. Cold shock caused mortality and reductions in swimming ability (time to exhaustion and lines crossed) in all species of fish at both age groups. Sensitivity was correlated to the magnitude of cold shock; a 10°C drop in temperature caused the highest mortalities. Ontogeny interacted with the severity of cold shock; the younger fish experienced higher mortalities and greater impairment to swimming ability. This study demonstrates the potential lethal and sub-lethal impacts of cold shock on freshwater fish at a critical life-history stage. Understanding the impacts of cold shock will aid management of freshwater ecosystems for the benefit of fish populations, with the current study identifying critical life stages to be considered in remediation and guiding thresholds necessary to reduce the impact of cold shock on native fish populations.

On the basis of evidence just reviewed, the hormonal requirements during IVM of mammalian oocytes for fertilization and developmental competence may be summarized as follows: 1. Nuclear maturation occurs "spontaneously," without follicular factors or hormones, in all mammalian species. 2. Cumulus cells are necessary during nuclear maturation in culture for fertilization and developmental competence. Their effect is enhanced by the addition of serum or follicular fluid to the maturation medium. 3. FSH retards nuclear maturation, perhaps thereby enhancing subsequent developmental competence by allowing more time for cytoplasmic maturation to occur before fertilization. The effects of FSH are mediated, in part, by soluble factors from cumulus or granulosa cells. 4. FSH in vivo before culture or added in vitro to IVM culture media enhances fertilization and stimulates steroidogenesis (progesterone and estradiol) in cumulus cells. Blockade of steroidogenesis prevents the enhancing effect of FSH on fertilization. Progesterone can substitute for FSH in enhancing fertilization of rat oocytes. 5. Other hormones enhance beneficial effects of FSH, with some apparent species differences: a. Rat: Progesterone may mediate the FSH effect. b. Cow, rabbit: Estradiol enhances the beneficial effect of FSH. c. Rabbit: Prolactin further enhances the effects of estradiol and FSH. d. Human: No evidence is available on the possible synergism between steroids and gonadotropins in enhancing in vitro maturation. It is clear that further research is required to elucidate the mechanisms of action of all the hormones that have been observed to influence oocyte maturation, and to establish the physiologic significance of most of these, particularly in species other than laboratory rodents. Major benefits to animal production and human health are likely to accrue from such research.

Early embryonic loss, caused by reduced embryo developmental competence, is the major cause of subfertility in humans and animals. This embryo developmental competence is determined during oocyte maturation and the first embryo divisions. Therefore, it is essential to identify the underlying molecules regulating these critical developmental stages. Cathepsin L (CTSL), a lysosomal cysteine protease, is involved in regulating cell cycle progression, proliferation and invasion of different cell types. However, CTSL role in mammalian embryo development is unknown. Using bovine in vitro maturation and culture systems, we show that CTSL is a key regulator for embryo developmental competence. We employed a specific CTSL detection assay in live cells to show that CTSL activity correlates with meiotic progression and early embryo development. Inhibiting CTSL activity during oocyte maturation or early embryo development significantly impaired oocyte and embryo developmental competence as evidenced by lower cleavage, blastocyst and hatched blastocyst rates. Moreover, enhancing CTSL activity, using recombinant CTSL (rCTSL), during oocyte maturation or early embryo development significantly improved oocyte and embryo developmental competence. Importantly, rCTSL supplementation during oocyte maturation and early embryo development significantly improved the developmental competence of heat-shocked oocytes/embryos which are notoriously known for reduced quality. Altogether, these results provide novel evidence that CTSL plays a pivotal role in regulating oocyte meiosis and early embryonic development.

Respiration measurements of human oocytes correlate with oocyte competence

Effects of SOF and CR1 media on developmental competence and cell apoptosis of ovine in vitro fertilization embryos

Selection of high potential embryos using time-lapse imaging: the era of morphokinetics

Known as one of the competences of the 21st century, research competence can help students navigate through the complexities of a continuously shifting world. This study aims to analyze the acquisition and development of this competence in a sample of 154 undergraduate students of two bachelor’s degrees in Education Sciences (Social Education and Pedagogy) of the Universitat Autònoma de Barcelona (Spain). We conducted a three-phase study, in which (1) the learning outcomes related to research competences declared in the syllabi were identified and mapped through a content analysis of each syllabus; (2) students’ perceptions about the development of these learning outcomes were gathered through a questionnaire; and (3) guidelines to foster research competences among these undergraduates were explored by a Delphi panel technique. The results show that communicative skills and state-of-art reviewing skills are the least present across the courses of both degrees. The design of research competency acquisition across courses is uneven and does not seem clearly articulated. The students’ perception is consistent with the shortcomings, or disarticulation, observed in the curriculum analysis. They consider that the most poorly acquired competencies are the state-of-the-art reviewing, content knowledge, and communicative skills. Apparently, more emphasis is given to reflective thinking and communicative skills; but still, it is necessary to strengthen the acquisition of scientific content, the search for trustworthy information. These results were discussed with two panels of experts from which guidelines were defined to improve the acquisition, development, and evaluation of the research competence through university training in this field.