Egg Fragments Research Articles

Inactivation of Salmonella enteritidis on the surface of eggs by air activated with gliding arc discharge plasma

Salmonella enteritidis, a Gram-negative foodborne pathogen, causes inflammation of the stomach and intestines. Poultry and poultry products are considered to be the main hosts of S. enteritidis, especially the most common edible eggs, and increase the risk of Salmonella infection. Therefore, developing the inactivation strategy of S. enteritidis on the surface of eggs is the key step during the egg production process. Gas plasma could effectively inactivate bacteria and fungi and is developed as a potential non-thermal sterilization method in the food industry. In this study, the plasma-activated air (PAA) prepared by the air activated with gliding arc discharge contained a variety of reactive species. When the PAA activated at the power of 50 W and 100 W was inducted into the incubation chamber, the numbers of S. enteritidis on egg fragments or the whole eggs were reduced below the detection limit. After PAA treatment, the eggshells exhibited no change in structure demonstrated by scanning electron microscope, the color of eggshells became a little decrease in red, the internal quality of both the raw egg and the cooked egg also exhibited no change, and trace reactive species remained in the albumen. Further, the PAA was also feasible for the batch treatment of stacked eggs. Therefore, this study supplied an effective and safe strategy for aseptic processing in the poultry industry.

Cretaceous dinosaur and crocodylomorph egg records of the Sanshui Basin, Guangdong Province, southern China

This paper describes newly discovered dinosaur and crocodylomorph egg fragments from the Upper Cretaceous Sanshui and Dalangshan formations of the Sanshui Basin of Guangdong Province, southern China. Despite the absence of macroscopic information, the eggshell specimens can be identified to the oofamilies Prismatoolithidae, Elongatoolithidae and Krokolithidae, and it is hypothesized that these three families of eggs correspond to troodontids, oviraptorids and crocodiloids, respectively. Comparison with egg fossils from Nanxiong Basin, Heyuan Basin and Ganzhou Basin highlights the similarity between these egg assemblages and those from Nanxiong Basin. The egg fossils found in the Sanshui and the Dalangshan formations enrich the known faunal types in the research area and facilitate further studies on the diversity of Late Cretaceous vertebrate assemblages in the Sanshui Basin.

PRESERVED MEMBRANE ON DINOSAUR EGGSHELL FRAGMENTS, UPPER JURASSIC MORRISON FORMATION, EASTERN UTAH

ABSTRACT Dinosaur eggshell fragments, from the Upper Jurassic Brushy Basin Member of the Morrison Formation, Utah, were examined using Field Emission Scanning Electron Microscope (FESEM), Energy Dispersive Spectroscopy, and Raman Spectroscopy. Analyses revealed that the mammillary tips on the shell interior contain carbonaceous residue. Comparison under the FESEM of these shells with modern bird shells, including some samples heated to diagenetic temperatures, indicate that the residue is degraded organic compounds (DOC). Bird egg membrane is composed of interlaced collagen fibers. Features observed on, and common to, modern bird and dinosaur egg fragments include: (1) irregular-shaped calcium carbonate grains “floating” in an organic matrix; (2) three-dimensional organic fiber matrix; (3) external calcium carbonate molds of fibers in the mammillary bodies; and in heated specimens, (4) carbonaceous residue with ovate to circular pores. However, unlike birds' eggs, the dinosaur eggs contain a calcium carbonate tube around fibrous organic material that emerges from the tube and spreads laterally in a ‘puddle-like' deposit. The sizes of circular organic matrix pores of the dinosaur egg fragments are significantly smaller than those in the bird shells. Gallus gallus domesticus eggshell membranes heated to diagenetic temperatures resulted in alteration of collagen fibers to gel-like substances. The organic matrix with ovate to circular pore openings and the puddle-like deposits in the dinosaur egg fragments are interpreted as the product of membrane thermal diagenesis. The recognition of carbonaceous residue of the shell membrane on dinosaur shell fragments opens newfound opportunities to explore DOC associated with fragmental dinosaur eggs.

A baurusuchid yearling (Mesoeucrocodylia, Crocodyliformes), from the Adamantina Formation, Bauru Group, Upper Cretaceous of Brazil

ABSTRACT Occurrences of young and immature individuals, relatively rare in the fossil record, are important due to the great amount of morphological and evolutionary information they reveal about a lineage’s development. Although crocodylomorphs are the most abundant terrestrial vertebrates found in the Bauru Basin, southeastern Brazil, even outnumbering dinosaurian materials, much remains to be understood about their anatomy, ecology, and ontogeny. Egg fragments, nests and nesting sites attributed to Baurusuchus have been previously described, but unfortunately none of these yielded embryonic or hatchling remains. Here, we describe, for the first time, skeletal material of a small notosuchian yearling, recovered from the Adamantina Formation, with osteological features consistent with a baurusuchid affinity. We provide and discuss osteological and histological evidence of its ontogenetic stage, revealing morphological characters distinct from most adult forms, including conspicuous centro-parapophyseal laminae and developed ventral keels. Computerised tomography data also allowed for the identification of incipient ossification and a novel ontogenetic feature in the diminishing volume of the frontal´s internal recesses. Similar materials will increase our understanding of notosuchian ontogeny and diversity, thus requiring growth characters to be integrated into future phylogenies.

Species criteria in palaeontology and ichnology and the possibilities of using ichnofossils in geology

Paleontology is a science between biology and geology thus paleontologists use both biological and geological approaches to solve different kinds of problems. One of the main issues for paleontologist is the use of species criteria and species identification. The fossil record shows evidence of evolution of separate phyla and the biosphere in general. A significant part of the biosphere is represented by soft-body animals. The marks of activities different animals have appeared in the fossil record at least from rocks of Ediacaran to modern age. They could be imprints of “sitting” or moving tracks (of invertebrates or vertebrates), evidence of birth (for instance, egg fragments), crawling traces of molluscs, etc. There are a plenty of issues regarding the identification of the nature of ichnofossils. Sometimes it is possible to identify animal species that left their traces or imprints. We observe ichnofossils on the surface and inside sedimentary rocks, but their identification is often impossible. Therefore, an artificial nomenclature is used for the naming of “species” of ichnofossils. Ichnofossils of different age and from various facial conditions are investigated on all continents. Ichnology as a relatively new branch of geology is developing due to the use of modern technological approaches.

INTESTINAL MICROBIOME BY HISTOCOPROLOGICAL ANALYSIS AND ITS CLINICAL SIGNIFICANCE

The histocoprological method was used to study stool samples from patients with gastrointestinal diseases to determine the presence of helminths and assess the state of the intestinal microbiome. The main complaints of patients were abdominal pain, bloating, constipation and diarrhea. The patients were divided into two groups: those who took antibiotics and those who did not. Evaluation of the microbial background by histological stool preparations was carried out in total, morphologically by the density of the location of microbial colonies and the intensity of their color. Helminthiasis was ascertained by the detection of fragments of small nematodes, larvae, their cuticles and eggs. A high percentage of depletion of the microbial background for drugs with a decrease in the number of microbial colonies was noted in the first group (65.1% of those who took antibiotics). Among children, a weakening of the microbiome was found in 42 (88% – who also took antibiotics), that is, more often. The negative effect of antibiotics and other pathogens on the microbial background required its correction with the appointment of sorbents and prebiotics. All examined patients were found to have helminthiases (nematodes and mixed forms). Deworming was carried out with nemazole at age-specific dosages. In 57 patients who re-passed the analysis, after complex treatment, there was a positive trend, clearly traced in feces preparations.

Impurities detection in edible bird’s nest using optical segmentation and image fusion

The cleanliness of edible bird’s nest (EBN) is among the determinative factors for market acceptance. As it is meant for human consumption, EBN should be free of any impurities or matter which are foreign to it, such as bird feathers, egg fragments and droppings. However, natural variations in composition, density and thickness impose inconsistency to the level of translucency and colour of EBN, resulting in intensity inhomogeneity in EBN images that substantially reduce the accuracy of the segmentation and detection of impurities. Consequently, the segmentation and detection of impurities, which are essential to visual automation in the cleaning and inspection processes, remain unsolved. This work proposes a novel optical segmentation method to segment impurities from the EBN, in order to facilitate the detection of impurities. EBN images captured under two different lighting scenarios, namely, low-angle blue-diffused lighting and red-diffused backlighting, were used to prepare the fused image for background-EBN-impurities segmentation. The applicability of the method was demonstrated by comparing the detection results with those of human inspectors. With a simple thresholding operation performed on fused images, the impurities detection algorithm recorded a true positive/recall rate of 93.39%, a precision of 71.17% and a false-negative detection rate of 4.8%. Despite the high misclassification rate of 32.25%, the algorithm was able to detect more than 93% of the impurities, compared to human inspectors, who required a second examination on the EBNs.

Animal remains from the el-Hamra Christian complex in the el-Ga'ab Depression, West Dongola (Sudan)

The animal remains discussed in this paper come from three archaeological sites in the el‑Hamra Christian complex, excavated within the frame of the el‑Ga'ab Depression archaeological, ethnographical and ecological project. During two seasons in 2013/2014 and 2014/2015, a team directed by Yahia Fadl Tahir collected and examined a total of 89 mammal, five ostrich egg and 16 mollusk remains. The bone assemblage was divided into seven groups representing the most and least attractive parts of the carcass in terms of nutritional value. Identified species include sheep (Ovis aries) and goat (Capra hircus), while other animal remains include ostrich egg fragments and mollusk species: Pila ovata, Melanoides tuberculata and Lanistes carinatus. Similarities can be observed in livestock husbandry and subsistence patterns in the early Christian period in the Dongola region, where the economy depended on small mammals like sheep and goats to provide milk and meat.

Thawing process calculation of egg ingredients particles in minced meat

Sausages from poultry meat are present on the domestic market. In this regard, the problem of improving the competitiveness of these products is urgent. One way to solve this problem is to replace part of the raw meat in the minced meat for sausages with chicken egg products (pasteurized liquid egg, egg white, yolk). Using egg products as ingredients of minced meat will help stabilize minced meat for sausages before and after heat treatment, increase the nutritional value of the finished product, and reduce its cost. However, currently, the mass fraction of egg ingredients in meat and egg products formulations does not exceed 5–10 %. This is due to the appearance of a specific taste, if it is exceeded, and because it is impossible to obtain a pattern of egg fragments in the section of the finished products, if necessary. This fact restricts the use of egg products as ingredients of meat and egg products. A technological method to eliminate these problems is freezing egg ingredients before adding to minced meat. In order to control the application of this method, the mechanism of changes in frozen egg ingredients during the preparation and heat treatment of minced meat for sausages is revealed. It was found that at the stage of minced meat mixing, the liquid part of the egg ingredients resulting from the thawing of frozen particles surface mixes with meat ingredients. Moreover, when unmoved relative to the surrounding minced meat, the frozen particles of egg ingredients are caught by the minced meat, and then locally coagulate in the process of meat and egg product heat treatment. The weight of the liquid phase resulting from the thawing of frozen egg ingredient particle and the weight of its remaining local part depend on the duration of the minced meat mixing process, its temperature and particle weight. Based on the knowledge about this mechanism, analytical equations are obtained using the energy balance method. They describe the duration of egg ingredients thawing in meat and egg products depending on the particle weight and the temperature of minced meat. The experimental data of the authors are used as a basis for calculating the process of egg ingredients thawing. The proposed calculation method will allow purposeful controlling the process of change in frozen egg ingredients aggregative state in minced meat for sausages, under production conditions.

Dynamic BMP signaling polarized by Toll patterns the dorsoventral axis in a hemimetabolous insect.

Toll-dependent patterning of the dorsoventral axis in Drosophila represents one of the best understood gene regulatory networks. However, its evolutionary origin has remained elusive. Outside the insects Toll is not known for a patterning function, but rather for a role in pathogen defense. Here, we show that in the milkweed bug Oncopeltus fasciatus, whose lineage split from Drosophila's more than 350 million years ago, Toll is only required to polarize a dynamic BMP signaling network. A theoretical model reveals that this network has self-regulatory properties and that shallow Toll signaling gradients are sufficient to initiate axis formation. Such gradients can account for the experimentally observed twinning of insect embryos upon egg fragmentation and might have evolved from a state of uniform Toll activity associated with protecting insect eggs against pathogens.

Spawning failure in the sea urchin Strongylocentrotus intermedius in the northwestern Sea of Japan: Potential environmental causes

The natural populations of the sea urchin Strongylocentrotus intermedius were studied along 350km of the coast of the Primorye region of Russia (northwestern Sea of Japan). Most of the surveys were carried out in Kievka Bay, where sea urchins were sampled monthly from April 2008 to April 2011. The sea urchin gonads became ripe in late July–August. However, in two out of three reproductive seasons, extremely high percentage of individuals that did not complete their reproductive cycle by spawning (95% and 53% of unspawned females in 2008 and 2009, respectively) was found. A large-scale egg fragmentation was observed to start in middle September. This phenomenon was also found to different extents in other populations of S. intermedius in the studied area. Unique characteristics of the reproductive cycle of S. intermedius displaying spawning failure were revealed: (1) the cleaning process associated with the resorption of numerous undischarged eggs and spermatozoa was unusually long, lasting for approximately 7months, and (2) the decrease in the gonadal index was significantly lower and occurred 2months later than in the case of normal spawning. Analysis of environmental factors that potentially modulate the spawning process in S. intermedius populations, such as temperature and phytoplankton concentration (measured as the chlorophyll а (Chl а) concentration), showed that large difference in percentage of spawned sea urchins occurred at the nearly identical temperature profiles. At the same time, the positive correlation (p<0.05) detected between the Chl а concentration and the proportion of spawned females of S. intermedius indicates that there is a relationship between the spawning of this species and the concentration of phytoplankton. Two major conclusions were drawn from the study results: (1) resorption of undischarged gametes begins regardless of whether spawning takes place, and (2) sea urchin spawning does not occur automatically after gamete maturation but is affected by environmental conditions. We proposed that the phenomenon of spawning failure of S. intermedius seemed to be attributable to low phytoplankton concentration in water column insufficient to trigger the sea urchin spawning.

Use of a duodenal serosal patch in the repair of a colon rupture in a female Solomon Island eclectus parrot

Case Description-A 444-g (0.98-lb) 4-year-old sexually intact female Solomon Island eclectus parrot (Eclectus roratus solomonensis) was referred and evaluated for a suspected colonic obstruction. Clinical Findings-The parrot had a 3-day history of not passing feces and lack of appetite following treatment of dystocia that included percutaneous collapse of the egg and manual removal of egg fragments via the cloaca. During this procedure, a tear in the cloacal mucosa developed. The tear was repaired via a midline cloacotomy. Although clinically stable at the time of referral, the parrot became lethargic and bradycardic and had delayed crop emptying. Treatment and Outcome-A midline celiotomy and cloacotomy were performed to relieve the colonic obstruction, during which the severely distended colon ruptured. The colonic defects were closed in a simple interrupted pattern, and a serosal patch was applied by use of the adjacent duodenum. The bird recovered uneventfully from anesthesia and was passing voluminous feces with mildly increased effort within 1 hour after surgery. At 3 weeks after surgery, the parrot was passing feces with no increase in effort and had a normal appetite. Clinical Relevance-Application of a duodenal serosal patch for repair of a colon rupture was successful in this parrot. Gastrointestinal obstruction is rare in birds, but should be considered in birds that have regurgitation, decreased fecal production, and gastrointestinal dilation. Because birds lack an omentum, serosal patching with adjacent duodenum should be considered as a viable option in avian surgery.

Eggshell Permeability: A Standard Technique for Determining Interspecific Rates of Water Vapor Conductance

Typically, eggshell water vapor conductance is measured on whole eggs, freshly collected at the commencement of a study. At times, however, it may not be possible to obtain whole fresh eggs but rather egg fragments or previously blown eggs. Here we evaluate and describe in detail a technique for modern laboratory analysis of eggshell conductance that uses fragments from fresh and museum eggs to determine eggshell water vapor conductance. We used fresh unincubated eggs of domesticated chickens (Gallus gallus domesticus), ducks (Anas platyrhynchos domesticus), and guinea fowl (Numida meleagris) to investigate the reliability, validity, and repeatability of the technique. To assess the suitability of museum samples, museum and freshly collected black-headed gull eggs (Larus ridibundus) were used. Fragments were cut out of the eggshell from the blunt end (B), equator (E), and pointy end (P). Eggshell fragments were glued to the top of a 0.25-mL micro test tube (Eppendorf) filled with 200 μL of distilled water and placed in a desiccator at 25°C. Eppendorfs were weighed three times at 24-h intervals, and mass loss was assumed to be a result of water evaporation. We report the following results: (1) mass loss between weighing sessions was highly repeatable and consistent in all species; (2) the majority of intraspecific variability in eggshell water vapor conductance between different eggs of the same species was explained through the differences in water vapor conductance between the three eggshell parts of the same egg (B, E, and P); (3) the technique was sensitive enough to detect significant differences between the three domestic species; (4) there was no overall significant difference between water vapor conductance of museum and fresh black-headed gull eggs; (5) there was no significant difference in water vapor conductance for egg fragments taken from the same egg both between different trials and within the same trial. We conclude, therefore, that this technique is an effective way of measuring interspecific water vapor conductance from eggshell fragments and that museum eggs are a suitable resource for such work.

A study of a Troodon egg containing embryonic remains using epifluorescence microscopy and other techniques

A partial egg containing embryonic skeletal elements represents the first Troodon egg collected from the Upper Cretaceous (Campanian) Judith River Formation of central Montana. The egg fragment contains disarticulated bones, including a vertebral centrum and a single tooth. Histological sections of a limb bone reveal six to eight layers of vascular canals, profuse vascular space, abundant osteocytes, and evidence of initial osteonal development. Histologically, the embryonic skeletal elements represent an earlier ontogenetic stage than similar bones in a Troodon egg from the contemporaneous Two Medicine Formation in Montana. The 1-mm-thick eggshell consists of mammillary, prismatic, and external layers. The external layer fluoresces brightly when viewed by epifluorescence and cathodoluminescence microscopy; however, this color intensity does not extend into the underlying prismatic layer, thus indicating a transition occurs between layers 2 and 3. The presence of three structural layers in Troodon may indicate a deeper origin of an external layer within non-avian theropods. Although commonly used in the study of carbonates, epifluorescence microscopy is rarely employed in the study of fossil eggs. This technique offers several advantages over cathodoluminescence analysis, including minimal sample preparation, lower cost, and greater structural definition of some features. Therefore, epifluorescence could be beneficial to future studies of fossil specimens.

Effects of cigarette smoke on fertilization and embryo development in vivo

To determine the effects of smoking on eggs and subsequent embryo development by maternal exposure to cigarette smoke. Mice were exposed to cigarette smoke or cigarette smoke condensate (CSC) for 4 weeks and then examined for development and telomere function of embryos in vitro after fertilization. In addition, the effects of continuous smoke on embryo development and telomere length were determined by treating mice for 4 weeks, followed by continuous exposure to cigarette smoke or CSC after fertilization. Laboratory study. CD1 mice. Mice were exposed to cigarette smoke or CSC. The percentage (rate) of blastocyst development, quality of embryos assessed by total cell number, apoptosis, Oct4 expression (a molecular marker of embryonic stem cells), telomere length and loss, and chromosomal instability were compared between smoke- and CSC- treated mice and sham-treated mice. Mice exposed to cigarette smoke or CSC for 4 weeks exhibited increased egg fragmentation or delayed fertilization, thus reducing development to blastocysts in vitro. Fragmented eggs showed increased reactive oxygen species. Mice exposed to smoke or CSC showed increased apoptosis and altered expression of Oct4 in developed embryos. The effects of smoke or CSC on embryo development showed a dose-dependent relationship to exposure time. Exposure to smoke or CSC beginning 4 weeks before fertilization altered expression of Oct4 and increased apoptosis in blastocysts. Notably, the rate of abnormal embryos significantly increased in the smoke and CSC groups. Smoke and CSC shortened telomeres in embryos, but their telomere shortening was not enough to induce major chromosome abnormalities in mice, which have unusually long telomeres. Together, the whole animal exposure model shows that cigarette smoke induces oxidative stress, telomere shortening, and apoptosis, and compromises embryo development in vivo.

Ravens as small mammal bone accumulators: First taphonomic study on mammal remains in raven pellets

The raven Corvus corax is one of the most common and widely distributed bird species in the northern hemisphere. Both predator and scavenger, its diet often comprises small mammals, whose bones and teeth are ejected through pellets after digestion. These pellets are frequently accumulated around the nest or roost sites, which can be used for years, even centuries. Until now, numerous studies have stressed the role of raptor pellet and mammalian scat accumulations as a source for small vertebrate palaeontological or archaeo(zoo)logical terrestrial assemblages. However, the raven, known from the Late Pliocene, has not yet been studied as a taphonomic agent. We present the first study on small mammal bone modifications from 567 raven pellets collected in Białowieża Primeval Forest (E Poland). A total of 1008 skull elements (teeth and jaws) and 812 main postcranial bones (long bones, girdles, talus, calcaneus), mainly belonging to rodents and shrews, were recovered from 129 pellets. The distinction of taphonomic features among the 5 main groups of prey (squirrels, large rodents, small rodents, shrews and moles) revealed a better representation and completeness of remains from the smallest species, and a variability in the proportion of digested teeth among different groups of prey. The global taphonomic signature of the small mammal bone assemblage appeared close to that of owls, but it placed the raven in an intermediate category of predators (between owl categories 1 to 3), according to the classification by Andrews (1990) [Andrews, P.J., 1990. Owls, caves and fossils, Natural History Museum Publications, London.]. Mineral remains from other vertebrate species (ungulates, lagomorphs, bats, birds, fish) were also frequently represented by small bone splinters (usually less than 2 cm long), egg fragments and complete elements (teeth, bones, hooves). Vegetal material, including seeds, was also frequent. The presence of such remains may be useful to distinguish a fossil bone assemblage made by raven from one originated from an owl prey accumulation. This study provides new insight to explain some small bone accumulations through Plio–Pleistocene and recent periods, particularly in mountain and cold areas. Due to its opportunistic exploitation of a wide variety of food sources, the raven may provide a more complete image of the fauna in the surrounding area of deposition than owl or small carnivore prey assemblages. Ravens associate often with open landscapes, large carnivores and human activities, a fact that might be also relevant for archaeological or archaeozoological considerations.

Radiolabelling of egg meals for gastric emptying studies: a comparison of 99mTc sulfur and 99mTc stannous colloids

To establish whether 99mTc stannous (Tc-Sn) colloid is a suitable alternative to 99mTc sulfur (Tc-S) colloid for gastrointestinal studies, we compared the per cent binding to egg solids (%BS) and radiochemical purity (RCP) of both colloids in digesting media. Egg white and yolk containing colloids were cooked separately and mashed. Samples of 4-5 g were digested over 2-3 h (37 degrees C) in excess simulated gastric juice (SGJ: 15 ml of 0.1 M HCl and 0.5 g.l-1 pepsin) or water, centrifuged, imaged with a gamma camera and the %BS computed. RCP was determined in aspirates taken from these preparations and from solutions of colloid added directly to SGJ. The %BS in egg white after 3 h in SGJ for both colloids were similar: Tc-Sn, 62+/-8 (n=12); Tc-S, 61+/-6 (n=8), but markedly lower than 95% (the often quoted literature value). Egg yolk was digested more rapidly than egg white: %BS after 2 h in SGJ for Tc-Sn colloid was 55+/-10 (n=5) in the yolk, compared to 77+/-4 (n=5) in the white (P<0.01). The RCP for Tc-S colloid alone in SGJ was >94% over 3 h but for Tc-Sn colloid was as low as 14%. For egg white, the RCP in SGJ was 91-96% for Tc-S and 80-91% for Tc-Sn. For egg yolk the RCPs in SGJ were similar for both colloids (>90%). The RCP in water digesting egg white or yolk containing either colloid was always lower than in the corresponding SGJ aspirates, indicating a leakage of small amounts of non-colloidal 99mTc. Although 99mTc-Sn almost completely dissociates in SGJ, once cooked in egg it is digested similarly to 99mTc-S. Variations in the size of digesting egg fragments and in SGJ composition can reconcile the lower %BS values obtained with previously reported higher results. 99mTc-Sn colloid cooked in egg appears suitable for gastrointestinal studies.

Age and stratigraphic reassessment of the fossil-bearing Laguna Umayo red mudstone unit, SE Peru, from regional stratigraphy, fossil record, and paleomagnetism

Abstract The thick red mudstone unit that crops out at Laguna Umayo (Puno department, southern Peru), here referred as LURMU, has yielded in different levels a fossil assemblage with plants and vertebrates (including mammals). On the basis of charophytes, the unit was initially assigned to the Vilquechico Formation (Maastrichtian-Danian), of regional extension, and the dinosaurian structure of egg fragments was interpreted as consistent with that age. Revision of the regional stratigraphy leads to reassignment of this unit to the Lower Munani Formation (Early Tertiary). Mammals from the LU-3 and Chulpas levels present affinities with forms from the Upper Paleocene of South America (Patagonia, Brazil). A bunodont marsupial, Chulpasia, is evidence for chronologic proximity to a transantarctic interchange with Australia at the end of the Paleocene. Furthermore, magnetostratigraphy of the LURMU reveals a single reverse polarity zone of 300 m thickness. Because of the new stratigraphic and paleomammalogic data, this long reverse polarity zone is likely correlative to Chron 26r (early Late Paleocene) or Chron 24r (latest Paleocene–earliest Eocene), or, less likely, to Chron 29r (latest Cretaceous–earliest Paleocene). The arguments previously invoked in favor of a Cretaceous age (charophytes, dinosaurian eggs) are critically evaluated, and correlation to Chron 24r is favored.

“Tertiary Dinosaurs” in the Nanxiong Basin, Southern China, Are Reworked from the Cretaceous

Abstract The Nanxiong and Shanghu Formations of southeastern China span the KT boundary interval and preserve an important paleontological record. A 1285‐m section across the KT boundary was measured, and lithological units were documented and sampled. Strata were deposited in alluvial fan/playa mudflat environments in a highly seasonal, semiarid climate. Previous workers placed the KT boundary at the Nanxiong/Shanghu formational contact. The uppermost Nanxiong and lowermost Shanghu Formations contain an assemblage of dinosaur egg fragments and Tertiary fossils, which led to the notion that dinosaurs survived into the Paleocene. On the basis of our results, we argue that the mixed KT assemblage is a result of debris flows reworking Cretaceous fossils. Depositional environments and paleoclimate did not change significantly across the KT boundary.

Formation of a large Vasa-positive germ granule and its inheritance by germ cells in the enigmatic Chaetognaths.

Chaetognaths (arrow worms) are abundant hermaphrodite marine organisms whose phylogenetic position amongst protostomes and deuterostomes is still debated. Ancient histological observations dating from a century ago described the presence in eggs of a large granule, presumed to be a germ plasm, and its probable inheritance in four primary germ cells (PGCs). Using videomicroscopy, electron microscopy and immunocytochemistry (labelling with anti-Vasa antibodies) we have followed the cycle of aggregation and dispersion of germ plasm and nuage material in eggs, embryos, PGCs and oocytes in several species of benthic (Spadella) and planctonic (Sagitta) chaetognaths. In these animals, germ cells and gametes can be observed in vivo throughout the 1-2 month life cycle. After describing internal fertilization in live animals we show that the single large (15 microm diameter) germ granule forms by a spiralling aggregation movement of small germ islands situated in the vegetal cortex at the time of first mitosis. We also demonstrate that the granule forms autonomously in unfertilized activated eggs or fertilized egg fragments. Once formed, the germ granule first associates with the cleavage furrow and is segregated into one of the first two blastomeres. The germ granule is then translocated from the cortex to the mitotic spindle during 3(rd) cleavage and remains in the single most-vegetal blastomere until the 32-cell stage. At the 64-cell stage the germ granule is partitioned as nuage material into two founder PGCs and further partitioned into four PGCs situated at the tip of the archenteron during gastrulation. These four PGCs migrate without dividing to reach the transverse septum, then proliferate and differentiate into oocytes and spermatocytes of two ovaries and two testes. We noted that germ plasm and nuage material were associated with mitochondria, the nucleus, the spindle and the centrosome during some stages of development and differentiation of the germ line. Finally, we demonstrate that a Vasa-like protein is present in the germ granule, in PGCs and in the electron-dense material associated with the germinal vesicle of oocytes. These features stress the conservation of cellular and molecular mechanisms involved in germ cell determination.