Estudio histológico de huevos ováricos partenogenéticos de Moina eugeniae, Olivier 1954

Moina eugeniae is one of the most abundant zooplankton species found in ponds and lakes in Buenos Aires Province. Its importance is due to the common use of cladocerans as food fish. The aim of the present study was to investigate the reproductive structures through histological techniques. Samples were taken with a plankton net (150 μm) from the Calderón lake (Buenos Aires) during Spring 2006. The specimens were anesthetized with CO2 “in situ” and fixed with formaldehyde 4%. Parthenogenetic females in different reproductive stages were selected to perform with them routine histological techniques. No males were identified during our study. The ovaries are pair, secular and disposed dorsally in the body. The oocytes are polyedric with three different stages of maturation: previtellogenic (dense nuclear cromatine), vitellogenic (abundant yolk in cytoplasm and large granules of cromatine in the nucleous) and mature (abundant lipidic drops in cytoplasm). Many of the morphological features observed are similar to those of Daphnia genus. Further investigation is needed to elucidate the reproductive cycle of this species.Instituto de Limnología "Raúl A. Ringuelet

Estudio histológico de huevos ováricos partenogenéticos de Moina eugeniae, Olivier 1954

Moina eugeniae is one of the most abundant zooplankton species found in ponds and lakes in Buenos Aires Province. Its importance is due to the common use of cladocerans as food fish. The aim of the present study was to investigate the reproductive structures through histological techniques. Samples were taken with a plankton net (150 μm) from the Calderón lake (Buenos Aires) during Spring 2006. The specimens were anesthetized with CO2 “in situ” and fixed with formaldehyde 4%. Parthenogenetic females in different reproductive stages were selected to perform with them routine histological techniques. No males were identified during our study. The ovaries are pair, secular and disposed dorsally in the body. The oocytes are polyedric with three different stages of maturation: previtellogenic (dense nuclear cromatine), vitellogenic (abundant yolk in cytoplasm and large granules of cromatine in the nucleous) and mature (abundant lipidic drops in cytoplasm). Many of the morphological features observed are similar to those of Daphnia genus. Further investigation is needed to elucidate the reproductive cycle of this species.Instituto de Limnología "Raúl A. Ringuelet

Estudio histológico de huevos ováricos partenogenéticos de Moina eugeniae, Olivier 1954

Moina eugeniae is one of the most abundant zooplankton species found in ponds and lakes in Buenos Aires Province. Its importance is due to the common use of cladocerans as food fish. The aim of the present study was to investigate the reproductive structures through histological techniques. Samples were taken with a plankton net (150 μm) from the Calderón lake (Buenos Aires) during Spring 2006. The specimens were anesthetized with CO2 “in situ” and fixed with formaldehyde 4%. Parthenogenetic females in different reproductive stages were selected to perform with them routine histological techniques. No males were identified during our study. The ovaries are pair, secular and disposed dorsally in the body. The oocytes are polyedric with three different stages of maturation: previtellogenic (dense nuclear cromatine), vitellogenic (abundant yolk in cytoplasm and large granules of cromatine in the nucleous) and mature (abundant lipidic drops in cytoplasm). Many of the morphological features observed are similar to those of Daphnia genus. Further investigation is needed to elucidate the reproductive cycle of this species.Instituto de Limnología "Raúl A. Ringuelet

Opal (Zn/Si) ratios as a nearshore geochemical proxy in coastal Antarctica

Author Posting. © American Geophysical Union, 2008. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Paleoceanography 23 (2008): PA2218, doi:10.1029/2007PA001576.During the last 50 years, the Antarctic Peninsula has experienced rapid warming with associated retreat of 87% of marine and tidewater glacier fronts. Accelerated glacial retreat and iceberg calving may have a significant impact on the freshwater and nutrient supply to the phytoplankton communities of the highly productive coastal regions. However, commonly used biogenic carbonate proxies for nutrient and salinity conditions are not preserved in sediments from coastal Antarctica. Here we describe a method for the measurement of zinc to silicon ratios in diatom opal, (Zn/Si)opal, which is a potential archive in Antarctic marine sediments. A core top calibration from the West Antarctic Peninsula shows (Zn/Si)opal is a proxy for mixed layer salinity. We present down-core (Zn/Si)opal paleosalinity records from two rapidly accumulating sites taken from nearshore environments off the West Antarctic Peninsula which show an increase in meltwater input in recent decades. Our records show that the recent melting in this region is unprecedented for over 120 years.The work was funded as part of NERC Antarctic Funding Initiative AFI4– 02. K.R.H. is funded by NERC grant NER/S/A/2004/12390

Groundwater discharge to the western Antarctic coastal ocean

Submarine groundwater discharge (SGD) measurements have been limited along the Antarctic coast, although groundwater discharge is becoming recognized as an important process in the Antarctic. Quantifying this meltwater path-way is important for hydrologic budgets, ice mass balances and solute delivery to the coastal ocean. Here, we estimate the combined discharge of subglacial and submarine groundwater to the Antarctic coastal ocean. SGD, including subglacial and submarine groundwater, is quantified along the WAP at the Marr Glacier terminus using the activities of naturally occurring radium isotopes (223Ra, 224Ra). Estimated SGD fluxes from a 224Ra mass balance ranged from (0.41 ± 0.14)×104 and (8.2 ± 2.3)×104m3 d−1. Using a salinity mass balance, we estimate SGD contributes up to 32% of the total freshwater to the coastal environment near Palmer Station. This study suggests that a large portion of the melting glacier may be infiltrating into the bedrock and being discharged to coastal waters along the WAP. Meltwater infiltrating as groundwater at glacier termini is an import-ant solute delivery mechanism to the nearshore environment that can influence biological productivity. More importantly, quantifying this meltwater pathway may be worthy of attention when predicting future impacts of climate change on retreat of tidewater glaciers

Minimal information for studies of extracellular vesicles (MISEV2023): From basic to advanced approaches

Extracellular vesicles (EVs), through their complex cargo, can reflect the state of their cell of origin and change the functions and phenotypes of other cells. These features indicate strong biomarker and therapeutic potential and have generated broad interest, as evidenced by the steady year-on-year increase in the numbers of scientific publications about EVs. Important advances have been made in EV metrology and in understanding and applying EV biology. However, hurdles remain to realising the potential of EVs in domains ranging from basic biology to clinical applications due to challenges in EV nomenclature, separation from non-vesicular extracellular particles, characterisation and functional studies. To address the challenges and opportunities in this rapidly evolving field, the International Society for Extracellular Vesicles (ISEV) updates its 'Minimal Information for Studies of Extracellular Vesicles', which was first published in 2014 and then in 2018 as MISEV2014 and MISEV2018, respectively. The goal of the current document, MISEV2023, is to provide researchers with an updated snapshot of available approaches and their advantages and limitations for production, separation and characterisation of EVs from multiple sources, including cell culture, body fluids and solid tissues. In addition to presenting the latest state of the art in basic principles of EV research, this document also covers advanced techniques and approaches that are currently expanding the boundaries of the field. MISEV2023 also includes new sections on EV release and uptake and a brief discussion of in vivo approaches to study EVs. Compiling feedback from ISEV expert task forces and more than 1000 researchers, this document conveys the current state of EV research to facilitate robust scientific discoveries and move the field forward even more rapidly