Microencapsulation Yield Assessment Using TGA

In this study, microcapsules containing different contents of different kinds of fragrances and with a regular spherical shape, 2,0–8,0 µm diameter, were synthesized in various core:shell ratios. Mint and cuir fragrances were successfully encapsulated in poly(urea-formaldehyde) (PUF) shell via in-situ polymerization. This was confirmed by optical microscope, scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR) studies. By observation from thermogravimetric analysis (TGA), it was found a relation between thermal gravimetric curves and the amount of fragrance encapsulated, which was later contrasted by ultraviolet-visible spectroscopy. In this way, comparatively, the yield percentage values can be quantitatively defined with a sufficient degree of accuracy by TGA methodPostprint (author's final draft

Estereotipos presentes en cuidadores y trabajadores de residencias de mayores extremeñas sobre las personas de la tercera edad

Nuestra sociedad está envejeciendo, esto es un hecho. El mundo en el que vivimos está mucho más urbanizado que antes y está sometido a un acelerado avance tecnológico. Todo esto trae consigo cambios irreversibles en la situación de muchos mayores (Moreno, 2012). Dada esta situación, nuestro objetivo en este estudio es analizar cuáles son los estereotipos más frecuentes entre los cuidadores o trabajadores en contacto directo con personas mayores dentro y fuera de residencias de la tercera edad. Simultáneamente el estudio desembocará en el análisis de posibles correlaciones positivas y negativas entre determinados estereotipos. El artículo finaliza con una exposición de las posibles consecuencias indirectas que la presencia de estos estereotipos puede suponer para la inclusión de los mayores como ciudadanos de pleno derecho en nuestra sociedad (Silveira, Agulló y Rodríguez, 2002).Our society is aging, this is a fact. We live in a urbanized world and it is submitted to an intensive technological advances. All that brings with it irreversible changes in the situation of many majors (Moreno, 2012). Before this situation, our aim in this study is analyze which are the most frequent stereotypes between the keepers or workers in direct contact with old people inside and out of residences of the third age. Simultaneously the study will end with the analysis of possible positive and negative correlations between certain stereotypes. The article finishes with an exhibition of the possible consequences that the presence of these stereotypes can suppose for the incorporation of the elder people as citizens of full rights in our society

Aceptación psicológica y apoyo afectivo familiar: variables de impacto en la satisfacción con la vida en personas mayores

Este artículo presenta un estudio científico sobre la satisfacción con la vida en una muestra extremeña de mayores. Tiene por objetivo, por un lado, describir su satisfacción o insatisfacción con la vida y por otro, cuestionar la influencia que determinados factores pueden ejercer sobre la misma. Este estudio, que se compone de tres partes principales, comienza con breve revisión de la literatura científica existente sobre la satisfacción con la vida en personas de la tercera edad. En este sentido, el marco teórico refleja con nitidez la naturaleza multidimensional y compleja de la calidad de vida y el grado de inconsistencia existente entre las investigaciones que pretenden un acercamiento a este tema. Por último, el artículo finaliza con una exposición de conclusiones relativas a la satisfacción vital de una muestra de mayores de la provincia de Badajoz. Gracias al estudio, podemos cuestionar la influencia inmediata directa y única de variables como la edad, la dependencia o la percepción de la propia salud y hasta la religión; así como pueden extraerse similitudes y diferencias en lo que respecta a la satisfacción vital de personas mayores que están viviendo en residencias o fuera de ellas.This article presents a scientific study about satisfaction with life in an Extremadura sample of adults. It is objective, on the one hand, to describe their satisfaction or dissatisfaction with life, and on the other hand, questioning the influence of multiple factors can exert on it. The study, which is made up of three main parts, introduces the subject focusing their attention on a brief review of exis- ting scientific literature on satisfaction with life in the elderly. In this sense, the theoretical frame- work reflects clearly the complex and multidimensional nature of the quality of life and the degree of inconsistency existing between research seeking an approach to this issue. Finally, the article con- cludes with an exhibition of conclusions about life satisfaction of a sample of adults in the province of Badajoz. Thanks to the study we can question the direct and only immediate influence of varia- bles such as age, dependence or the perception of their own health and to religion, as well as simi- larities and differences in life satisfaction of elderly people who are living in homes or outside them may be removed

Apoyos percibidos y deseos en la adolescente: variables que operan en la experiencia de felicidad con el embarazo

Este artículo presenta un estudio científico sobre la felicidad que experimentan las adolescentes con su incipiente gestación. Tiene por objeto, por un lado, verificar si es posible en nuestra muestra de 27 embarazadas de entre 15 y 24 años, esa satisfacción con la gestación, a pesar de no ser en ningún caso planificada; y por otro, cuestionar la influencia que determinados factores pueden ejercer sobre la misma. Asimismo, previamente se introduce una breve revisión de la literatura científica existente sobre la temática. En este sentido, el marco teórico refleja la naturaleza multidimensional y compleja de la felicidad y el grado de inconsistencia existente entre las investigaciones que pretenden un acercamiento a esta realidad. Por último, el artículo finaliza con una exposición de conclusiones relativas al papel que ejercen la edad y el apoyo en el proceso gestacional. Gracias al estudio, podemos cuestionar la influencia inmediata, directa y única de estas variables, focalizando nuestra atención en otras como son los deseos y las motivaciones de las gestantes.This article presents a scientific study about the level of happiness or satisfaction with the gestational development of 27 pregnant women between 15 and 24 years. This study aim at describing their satisfactions or dissatisfactions with the gestation and the influence that certain factors can exerts on a number of them. Likewise the first section offers an introduction of the scientific existing literature about the satisfaction with the pregnancy. In this respect, the theoretical framework reflects the multidimensional and complex nature of the satisfaction or happiness and the level of existing inconsistency between the investigations that claim an approximation to this topic. Finally, the article finishes with an exhibition of findings related to the role that the age and the support exerts in the gestation. The study found out that we can challenge the immediate, direct and only leverage of variables such as gestational age or perception of support, focusing attention in others such us wishes or motivations of pregnant adolescents.peerReviewe

Dynamic environmental conditions recorded by the trace fossil Teichichnus and event beds during deposition of the basal Vaca Muerta Formation in the central Neuqu´en Basin (Argentina)

The mud-dominated part of the basal Vaca Muerta Formation in the central Neuquén Basin accumulated mainly under dysoxic conditions as indicated by the absence of both fine lamination and large burrows, typical of anoxic and oxic conditions, respectively. Event beds and large, strata-bound concretions preserving a nearly uncompacted sediment fabric document rather discontinuous deposition, in particular as concretions must reside within the zone of carbonate supersaturation for a prolonged period of time to form. The mudrock hosts numerous ash layers. Among them is a bed up to 40 cm-thick that was deposited by storm-induced currents and later became calcified. It contains abundant, winding Teichichnus up to 220 cm-long. The trace producers partly reworked their own spreite and probably applied a gardening and sequestrichnial nutritional strategy (that is collecting and stowing of nutritional material in the burrow for later utilization). The spreite fill documents depositional processes that delivered argillaceous sediment and provided oxygen. The ash originally constituting the Teichichnus bed originated from the volcanic arc west of the basin. In contrast, the erosive surface limiting the Teichichnus bed is covered by mud, implying sediment delivery from the east or south where rivers entered the basin while the climate was (at least seasonally) humid, whereas aridity increased towards the north. Consequently, an estuarine circulation likely developed and prevailed during the initial transgression of the lower Vaca Muerta Formation while cold Palaeo-Pacific water flowed into the subsiding and expanding basin. Later, during prevailing dry climate, an anti-estuarine circulation was probably established

Estudi de la immunogenicitat de Norovirus humans i de la seua interacció amb receptors cel·lulars

Noroviruses (NoVs) are the main cause of sporadic cases and outbreaks of acute gastroenteritis (Tam et al., 2012; Gastanaduy et al., 2013) and are globally associated with a large burden of disease (Patel et al., 2008). NoVs are a highly diverse group of viruses, although over the past two decades most reported NoV outbreaks and epidemics have been caused by NoV GII.4 genotype. Phylogenetic analyses of the GII.4 strains circulating in the last 20 years have shown that this genotype can be divided into distinct variants, which peak and wane over time in a similar pattern to that described for influenza viruses (Buesa et al., 2008; Siebenga et al., 2009; Koelle et al., 2006). In recent years different susceptibilities to NoV infection, depending on their HBGA phenotypes have been reported (Hutson et al., 2004). NoVs belong to the Caliciviridae family and are classified in 5 genogroups (GI-GV), although genogroup I (GI) and GII cause most human NoV infections. The genome is organized in three open reading frames (ORFs): ORF1, ORF2 and ORF3. The VP1, encoded by ORF2, is the major capsid protein, which is further organized into the N-terminal (N), the shell (S), and the protruding (P) domains. The P domain can be further divided into two subdomains: P1 and P2 (Prasad et al., 1999). The P1 subdomain forms the anchoring portion of the P dimer connecting it to the S domain, while the P2 subdomain is exposed on the surface of the capsid protein and is the most variable region of the virus. The main epitopes for immunorecognition and the histo-blood group antigen (HBGA) binding domains reside within this P2 subdomain. The emergence and accumulation of mutations along the P2 subdomain is the main driver of evolution for GII.4 strains, and results in new epidemic strains with altered antigenicity and HBGA binding properties (Allen et al., 2008, 2009; Shanker et al., 2011; Debbink et al., 2012). The cellular receptors that lead to norovirus infections have not been completely characterized yet, but it has been proposed that NoVs are likely to attach to either HBGA expressed on the gastroduodenal epithelial cells of secretor-positive individuals (Marionneau et al., 2002). However, a recent study has shown that NoV could bind to enterocytes independently of HBGAs (Murakami et al., 2013). To date no cell culture system has shown evidence of supporting norovirus propagation, Caco-2 cells, originally derived from human colorectal carcinoma expressing carbohydrates of the histo-blood group family on their surface, allow significant attachment of norovirus VLPs but only when these cells are differentiated. The C-terminal of the VP1 (P domain) of NoVs has the ability to auto-assemble into subviral particles, termed P particles (Tan & Jiang, 2005). Previous work showed that P particles retain the capacity to bind to saliva samples and to synthetic HBGA and that are also immunogenic, making them a valuable tool for the study of viral attachment and for the development of vaccines (Tan et al., 2008, 2011). In this study, the baculovirus expression system in insect cells was used to produce and purify the biologically active form of NoV VLPs from GII.4-1999 (GII.4-v0), GII.4-Hunter_2004 (GII.4-v2) and GII.4-Den Haag_2006b (GII.4-2006b) NoV strains. On the other hand, P particles (P-GI.1, P-GII.4-VA387, and P-GII.9) and the P domain (P-GII.4-2007_Apeldoorn) were produced in bacteria (E. coli) as recombinant proteins tagged with histidines (6xHis), and purified by FPLC in Ni-NTA columns. After the immunization of mice with the different purified NoV VLPs, the mAbs obtained by limiting dilution strongly recognized the P domain of the homologous variant, being indicative of the immunodominance of this region and corroborating the importance of the epitopes previously described in this domain (Zakikhany et al., 2012). Moreover, the av0 mAb also recognized the homologous P particle (P-GII.4-VA387 with a 97’88% of identity), indicating that P particles are antigenically comparable with the entire VLPs. Polyclonal antiserum were obtained from VLPs mix (GII.4-v0, GII.4-v2 and GII.3) immunized rabbit and recognized all of the variants used, both VLPs and P particles, with the exception of the P particle derived from a GI.1 strain. Therefore P particles contain variant-specific epitopes within genotypes but not between genogroups. Another objective of this thesis was to determine the epitope recognized by the anti-2006b mAb (3C3G3) which was performed by phage display technique. This mAb recognizes an epitope formed by 11 residues located into the P2 subdomain of NoV VP1 capsid protein, close to the blockade epitopes described. Thus being able to conduct inhibitory studies to identify biological activity. The binding properties to D-Caco-2 cells of virus-like particles (VLPs) of the different variants of NoV GII.4 and of P particles have been assessed by immunofluorescence, as well as inhibition of binding by: a) saliva; b) porcine gastric mucin (PGM); c) the monoclonal antibodies (mAbs) produced against NoV VLPs; and d) anti-Lewis antigens (Lea, Leb, Lex and Ley) or anti-H antigens (H1 and H2). These assays were performed in order to further investigate the interactions between NoVs and the cellular surface. The results were also compared with binding and blocking salivary assays by ELISA. All VLPs, but not P particles in the same conditions, were able to bind to saliva and D-Caco-2 cells. The different mAbs anti-NoV used blocked the VLP binding to saliva as well as PGM and D-Caco-2 cells, in a dose-dependent manner. But one interesting result when comparing blocking assays in both saliva and D-Caco-2 cells was that while in salivary assays the anti-Lewis or anti-H antigens used blocked the VLP binding, the HBGA blocking on the surface of D-Caco-2 cells did not affect NoV VLP binding. Furthermore, no co-localisation of HBGA and NoV VLPs was observed by immunofluorescence. These results suggest that binding to Caco-2 cells could be mediated by other receptors different from HBGAs, in addition to these. It was also studied the IgG antibody prevalence against NoV GII.4 in a Spanish population using the recombinant P domain of the NoV GII.4-Apeldoorn_2007 variant as the coating antigen in ELISA. Baculovirus-expressed virus-like particles (VLPs) of NoV GII.4-Den Haag_2006b variant were also used as antigen to compare seroreactivity. Of the 434 serum specimens analyzed, 429 (98.6 %) had antibodies against the P domain. The comparison of reactivities of 30 serum samples to the NoV GII.4 P polypeptide and VLP showed reproducible results with a correlation coefficient of r = 0.607. Titers of antibodies to the P domain increased gradually and significantly with age, reaching the highest levels at the age group of 41-50 years. These results confirm the high prevalence of NoV GII.4 infections in our community from early childhood. Finally, it is also presented the data on the immunogenicity of the NoV in natural NoV infections in humans. The results showed that the NoV elicits a humoral immune response in people that had been naturally infected by NoV. The IgG serical antibodies developed against the NoV in individuals suffering acute NoV gastroenteritis, present cross-reactivity against more than one genotype, but not against different genogroups, and are capable of blocking the NoV VLPs binding to saliva.Noroviruses (NoVs) are the main cause of sporadic cases and outbreaks of acute gastroenteritis (Tam et al., 2012; Gastanaduy et al., 2013) and are globally associated with a large burden of disease (Patel et al., 2008). NoVs are a highly diverse group of viruses, although over the past two decades most reported NoV outbreaks and epidemics have been caused by NoV GII.4 genotype. Phylogenetic analyses of the GII.4 strains circulating in the last 20 years have shown that this genotype can be divided into distinct variants, which peak and wane over time in a similar pattern to that described for influenza viruses (Buesa et al., 2008; Siebenga et al., 2009; Koelle et al., 2006). In recent years different susceptibilities to NoV infection, depending on their HBGA phenotypes have been reported (Hutson et al., 2004). NoVs belong to the Caliciviridae family and are classified in 5 genogroups (GI-GV), although genogroup I (GI) and GII cause most human NoV infections. The genome is organized in three open reading frames (ORFs): ORF1, ORF2 and ORF3. The VP1, encoded by ORF2, is the major capsid protein, which is further organized into the N-terminal (N), the shell (S), and the protruding (P) domains. The P domain can be further divided into two subdomains: P1 and P2 (Prasad et al., 1999). The P1 subdomain forms the anchoring portion of the P dimer connecting it to the S domain, while the P2 subdomain is exposed on the surface of the capsid protein and is the most variable region of the virus. The main epitopes for immunorecognition and the histo-blood group antigen (HBGA) binding domains reside within this P2 subdomain. The emergence and accumulation of mutations along the P2 subdomain is the main driver of evolution for GII.4 strains, and results in new epidemic strains with altered antigenicity and HBGA binding properties (Allen et al., 2008, 2009; Shanker et al., 2011; Debbink et al., 2012). The cellular receptors that lead to norovirus infections have not been completely characterized yet, but it has been proposed that NoVs are likely to attach to either HBGA expressed on the gastroduodenal epithelial cells of secretor-positive individuals (Marionneau et al., 2002). However, a recent study has shown that NoV could bind to enterocytes independently of HBGAs (Murakami et al., 2013). To date no cell culture system has shown evidence of supporting norovirus propagation, Caco-2 cells, originally derived from human colorectal carcinoma expressing carbohydrates of the histo-blood group family on their surface, allow significant attachment of norovirus VLPs but only when these cells are differentiated. The C-terminal of the VP1 (P domain) of NoVs has the ability to auto-assemble into subviral particles, termed P particles (Tan & Jiang, 2005). Previous work showed that P particles retain the capacity to bind to saliva samples and to synthetic HBGA and that are also immunogenic, making them a valuable tool for the study of viral attachment and for the development of vaccines (Tan et al., 2008, 2011). In this study, the baculovirus expression system in insect cells was used to produce and purify the biologically active form of NoV VLPs from GII.4-1999 (GII.4-v0), GII.4-Hunter_2004 (GII.4-v2) and GII.4-Den Haag_2006b (GII.4-2006b) NoV strains. On the other hand, P particles (P-GI.1, P-GII.4-VA387, and P-GII.9) and the P domain (P-GII.4-2007_Apeldoorn) were produced in bacteria (E. coli) as recombinant proteins tagged with histidines (6xHis), and purified by FPLC in Ni-NTA columns. After the immunization of mice with the different purified NoV VLPs, the mAbs obtained by limiting dilution strongly recognized the P domain of the homologous variant, being indicative of the immunodominance of this region and corroborating the importance of the epitopes previously described in this domain (Zakikhany et al., 2012). Moreover, the av0 mAb also recognized the homologous P particle (P-GII.4-VA387 with a 97’88% of identity), indicating that P particles are antigenically comparable with the entire VLPs. Polyclonal antiserum were obtained from VLPs mix (GII.4-v0, GII.4-v2 and GII.3) immunized rabbit and recognized all of the variants used, both VLPs and P particles, with the exception of the P particle derived from a GI.1 strain. Therefore P particles contain variant-specific epitopes within genotypes but not between genogroups. Another objective of this thesis was to determine the epitope recognized by the anti-2006b mAb (3C3G3) which was performed by phage display technique. This mAb recognizes an epitope formed by 11 residues located into the P2 subdomain of NoV VP1 capsid protein, close to the blockade epitopes described. Thus being able to conduct inhibitory studies to identify biological activity. The binding properties to D-Caco-2 cells of virus-like particles (VLPs) of the different variants of NoV GII.4 and of P particles have been assessed by immunofluorescence, as well as inhibition of binding by: a) saliva; b) porcine gastric mucin (PGM); c) the monoclonal antibodies (mAbs) produced against NoV VLPs; and d) anti-Lewis antigens (Lea, Leb, Lex and Ley) or anti-H antigens (H1 and H2). These assays were performed in order to further investigate the interactions between NoVs and the cellular surface. The results were also compared with binding and blocking salivary assays by ELISA. All VLPs, but not P particles in the same conditions, were able to bind to saliva and D-Caco-2 cells. The different mAbs anti-NoV used blocked the VLP binding to saliva as well as PGM and D-Caco-2 cells, in a dose-dependent manner. But one interesting result when comparing blocking assays in both saliva and D-Caco-2 cells was that while in salivary assays the anti-Lewis or anti-H antigens used blocked the VLP binding, the HBGA blocking on the surface of D-Caco-2 cells did not affect NoV VLP binding. Furthermore, no co-localisation of HBGA and NoV VLPs was observed by immunofluorescence. These results suggest that binding to Caco-2 cells could be mediated by other receptors different from HBGAs, in addition to these. It was also studied the IgG antibody prevalence against NoV GII.4 in a Spanish population using the recombinant P domain of the NoV GII.4-Apeldoorn_2007 variant as the coating antigen in ELISA. Baculovirus-expressed virus-like particles (VLPs) of NoV GII.4-Den Haag_2006b variant were also used as antigen to compare seroreactivity. Of the 434 serum specimens analyzed, 429 (98.6 %) had antibodies against the P domain. The comparison of reactivities of 30 serum samples to the NoV GII.4 P polypeptide and VLP showed reproducible results with a correlation coefficient of r = 0.607. Titers of antibodies to the P domain increased gradually and significantly with age, reaching the highest levels at the age group of 41-50 years. These results confirm the high prevalence of NoV GII.4 infections in our community from early childhood. Finally, it is also presented the data on the immunogenicity of the NoV in natural NoV infections in humans. The results showed that the NoV elicits a humoral immune response in people that had been naturally infected by NoV. The IgG serical antibodies developed against the NoV in individuals suffering acute NoV gastroenteritis, present cross-reactivity against more than one genotype, but not against different genogroups, and are capable of blocking the NoV VLPs binding to saliva

Icnología de los depósitos marinos miocenos de Patagonia: el rol de la fauna evolutiva moderna en ecosistemas infaunales del Neógeno

Los depósitos neógenos de Patagonia se caracterizan por presentar icnofaunas extremadamente diversas, incluyendo una gran variedad de estructuras de alimentación (e.g., Asterosoma, Helicodromites, Patagonichnus, Phycosiphon, Rhizocorallium, Rosselia, Teichichnus), pastoreo (e.g., Macaronichnus, Nereites, Scolicia, Taenidium) y habitación (e.g., Balanoglossites, Gastrochaenolites, Gyrolithes, Ophiomorpha, Siphonichnus, Sinusichnus, Spongeliomorpha, Schaubcylindrichnus, Thalassinoides), y de manera subordinada, trazas de locomoción (e.g., Protovirgularia) y equilibrio (e.g., Scalichnus). Los depósitos marinos abiertos se caracterizan por un intenso grado de bioturbación, complejas estructuras de escalonamiento y alta icnodiversidad. Por el contrario, los depósitos restringidos salobres y dominados por mareas, presentan un menor grado de bioturbación e icnodiversidad, así como también una estructura de escalonamiento notoriamente menos compleja. En estos últimos, las icnoasociaciones tienden a ser pauciespecíficas o monoespecíficas. Las suites de sustratos firmes, típicamente caracterizadas por Gastrochaenolites y Thalassinoides, se presentan tanto en depósitos marinos marginales como marinos abiertos. La compleja estructura de escalonamiento observada en las icnofaunas marinas normales del Neógeno de Patagonia refleja una fina partición del ecoespacio infaunal y un uso eficiente de los recursos. Las estructuras de equinodermos irregulares son abundantes en los depósitos marinos abiertos, mientras que las de crustáceos y bivalvos dominan tanto las asociaciones marinas abiertas como las marinas restringidas, registrando el auge de la Fauna Evolutiva Moderna. Estas observaciones son consistentes con las tendencias exhibidas por el registro de fósiles corpóreos, las cuales muestran que para las sucesiones de latitudes medias del Cenozoico tardío, las paleocomunidades marinas presentan una mayor representación de organismos infaunales, en especial excavadores profundos. Más aun, la comparación de las icnofaunas marinas someras cenozoicas con otras de ambientes similares en el Paleozoico y Mesozoico pone de manifiesto cambios a escala macroevolutiva en la configuración de la icnofacies de Cruziana, reflejando innovaciones significativas a nivel paleobiológico y ecológico.Simposio IV: Icnología: su aporte en interpretaciones paleoecológicas y paleobiológicasFacultad de Ciencias Naturales y Muse

Tidal signature recorded in burrow fill

The arrangement of sediment couplets preserved in Thalassinoides shafts suggests that tides regulated the passive filling of these trace fossils and, thus, represent tubular tidalites. The thickness variation in individual layers and couplets implies a mixed diurnal, semi-diurnal tidal signature where packages of either thick-layered or thin-layered couplets alternate. Calcarenitic sediment accumulated when tidal current velocity was too high to allow deposition of mud, whereas a marly mud layer is interpreted to have formed during more tranquil times of a tidal cycle (in particular, low-tide slack water). The tidal record within the burrows covers a few weeks and the corresponding spring-neap cycles. The fill of the Thalassinoides shafts is the only known record to decipher the tidal signature from otherwise totally bioturbated sediments. These deposits accumulated in a lower-shoreface to upper-offshore setting during the late Miocene on a shallow shelf extending from the Atlantic Ocean to the west into northern Patagonia. The fill of all investigated burrows started around spring tide and, thus, the behaviour of the burrow producers - probably crustaceans - is speculated to have been affected by tides or the high water level because all studied burrows became abandoned around the same period of a tidal cycle.Fil: Wetzel, Andreas. Universidad de Basilea; SuizaFil: Carmona, Noelia Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentina. Universidad Nacional de Río Negro. Sede Alto Valle. Instituto de Investigaciones en Paleobiología y Geología; ArgentinaFil: Ponce, Juan Jose. Universidad Nacional de Río Negro. Sede Alto Valle. Instituto de Investigaciones en Paleobiología y Geología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentin

Gyrochorte "highways" and their environmental significance in shallow-marine sediments

The reworking of a trace by a subsequently following organism represents a so-called sequorichnial behavior and leads to formation of a “burrowing highway”. Burrowing highways occur more frequently than assumed in the fossil record. Their ichnological and sedimentological meaning is elucidated by using the trace fossil Gyrochorte. Gyrochorte producers exploiting sandy event beds tend to use “burrowing highways” in the same direction. Evidently, the Gyrochorte producers are thigmotactically highly sensitive as they can recognize a burrow produced by the same species because of the less densely packed grains, a somewhat increased mud content, and supposedly mucus segregated within the burrow. These changes make the reworking of pre-existing burrows energetically advantageous. However, in shallow-marine settings mucus is degraded rapidly and loose sediment consolidates in a short while. Therefore, the time to recognize a pre-existing burrow appears to be limited and a rather high number of organisms is a prerequisite for reutilization of a previous trace. “Burrow highways” potentially represent an additional criterion to characterize an opportunistic population strategyFil: Wetzel, Andreas. Universität Basel; SuizaFil: Carmona, Noelia Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Río Negro. Sede Alto Valle. Instituto de Investigaciones en Paleobiología y Geología; ArgentinaFil: Ponce, Juan Jose. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Río Negro. Sede Alto Valle. Instituto de Investigaciones en Paleobiología y Geología; Argentin