Experimental neoichnology of post-autotomy arm movements of sea lilies and possible evidence of thrashing behaviour in Triassic holocrinids

Echinoderms exhibit remarkable powers of autotomy. For instance, crinoids can shed arm and stalk portions when attacked by predators. In some species, it has been reported that the autotomized arms display vigorous movements, which are thought to divert the attention of predators. This phenomenon, however, has not been well explored. Here we present results of experiments using the shallowest water species of living stalked crinoid (Metacrinus rotundus) collected at 140 m depth. A wide range of movements of detached arms, from sluggish writhing to violent flicks, was observed. Interestingly, autotomized arms produce distinct traces on the sediment surface. They are composed of straight or arched grooves usually arranged in radiating groups and shallow furrows. Similar traces were found associated with detached arms of the oldest (Early Triassic) stem-group isocrinid (Holocrinus). This finding may suggest that the origins of autotomy-related thrashing behaviour in crinoids could be traced back to at least the Early Triassic, underscoring the magnitude of anti-predatory traits that occurred during the Mesozoic Marine Revolution. A new ethological category, autotomichnia, is proposed for the traces produced by thrashing movements of shed appendages

A new Middle Devonian (Givetian) psammosteid (Vertebrata : Heterostraci) from Poland

A new genus and species of psammosteid heterostracan, Psarkosteus mediocris gen. et sp. nov., is described from the Middle Devonian (Givetian) of the Skały Formation, the Holy Cross Mountains, Poland. The dorsal plate of Psarkosteus is constricted in its anterior part and the postorbital plate is long and narrow. Both features, along with the morphology and variety of tubercles, distinguish it from other representatives of the group. Most distinctive are big, teardrop-shaped tubercles, each with a flat or slightly concave surface and with its tip directed posteriorly, and a crenulated base, located along the branchial plates. The lateral line system in Psarkosteus is similar to that of Drepanaspis gemuendenensis and confirms earlier reconstructions

New cranial material of the acanthothoracid placoderm Palaeacanthaspis vasta from the Lower Devonian of Podolia-phylogenetic and taxonomic significance

The Early Devonian vertebrates of Podolia in Ukraine are well known thanks to the material of the basal arthrodire placodenn genus Kujdanowiaspis, originally mentioned by Brotzen in 1934. The anatomical fame of Kujdanowiaspis brought by Erik Stensio almost eclipsed the presence of the acanthothoracid placoderm Palaeacanthapsis vasta in the underlying beds, with the original material of P. vasta being less well preserved and abundant than that of Kujdanowiaspis. Here we describe a newly discovered specimen of the acanthothoracid P. vasta from the Lochkovian of Podolia (Ukraine). The specimen, although incomplete, is very well preserved in three dimensions and allows a thorough description of its external morphology, which is compared to that of Romundina stellina and other well-known Acanthothoraci. A phylogenetic analysis is performed and the acanthothoracid nature of Palaeacanthaspis is confirmed. However, the position of Palaeacanthaspis within the Acanthothoraci remains uncertain, and its resemblance with Romundina could be due to either synapomorphies or symplesiomorphies. Similarities and differences between the two forms are exposed, and lead to the lack of synonymy at the specific level. Generic synonymy is also questioned for the first time but remains equivocal

Comments on the Squamation of Polish Lower Devonian Porolepiforms

Porolepiform scales from the Lower Devonian of the Holy Cross Mountains, Poland, described from the ‘placoderm sandstone’ of the Daleszyce area, are revised. The aim of the present article is to organize the recently collected, but not formally described, porolepiform material from the Holy Cross Mountains, as well as specimens from erratic boulders collected near Gdynia (northernmost Poland), which can be referred to Porolepis. Previously collected and new material was found to contain at least two sarcopterygian taxa: Porolepis and Heimenia. Based on morphological and histological features, the described material has been divided into two scale assemblages. The first, which is assigned to Porolepis, possesses cosmine cover on the entire exposed area; in the second, assigned to Heimenia, the cosmine cover is reduced or absent. These features prove to be stable regardless of the position of the scale on the body and thus are taxonomically informative

Numerical and Physical Simulation of MAG Welding of Large S235JRC+N Steel Industrial Furnace Wall Panel

This paper presents the results of a study on the development of a Metal active gas (MAG) welding technology for an industrial furnace component made of steel S235JRC+N with respect to the minimizationof welding deformation. A numerical simulation of the welding process was performed in the first phase of the research. The numerical simulation was carried out with the SYSWELD software. For the numerical simulation of the welding process, the FEM method was used. In the simulation, four variants of restraint of the industrial furnace wall panel elements during the execution of the welding process were investigated. They differed in the number of restraints (model 1–4). It was found that the difference between the maximum mean strain in model 1 and the lowest mean strain in model 4 was only 11%. A physical simulation of the welding process was then performed with a restraint variant according to model 1. The displacement results obtained from the physical simulation of the welding process were compared with the displacement results from the numerical simulation. Discrepancies between numerical and physical simulation displacement values were found. The quality of selected welded joints was also evaluated. Visual testing (VT) and measurements of weld geometries were performed for this purpose. Metallographic tests and hardness measurements were performed to determine of influence of the welding process on the microstructure of the welded joint area, especially the heat affected zone (HAZ). The results obtained confirm the correctness of the assumptions made regarding the technology of manufacturing the furnace wall panels

A glimpse of a fish face : an exceptional fish feeding trace fossil from the Lower Devonian of the Holy Cross Mountains, Poland

An exceptionally well-preserved assemblage of numerous invertebrate and vertebrate trace fossils is described from the Lower Devonian of the Holy Cross Mountains, southern Poland. Two trace-bearing horizons occur in the shallow-marine sequence that is exposed in a small outcrop near Ujazd village. One of the trace fossils is preserved as a bilobate, generally elliptical, epichnial pit is described as Osculichnus tarnowskae isp. nov. and interpreted as a unique example of praedichnia. Neoichnologic experiments and observations indicate that the ichnogenus Osculichnus was produced by feeding fish. The fish producing O. tarnowskae probably hunted bivalves, polychaetes and arthropods, which are represented by invertebrate trace fossils in the same horizons. The overall shape and morphological details of O. tarnowskae suggest that it was made by a lungfish broadly similar to Dipnorhynchus. The trace provides the first direct evidence for Devonian lungfish feeding behaviour, as well as the first record of three-dimensional soft-tissue morphology of the snout area of an Emsian representative of this group. The trace fossils from Ujazd provide new insight into the palaeoecology and taphonomy of the Lower Devonian of the Holy Cross Mountains

Biofilm-Formation Ability and the Presence of Adhesion Genes in Coagulase-Negative Staphylococci Isolates from Chicken Broilers

The aim of the study was to analyze the biofilm-production capacity of 87 coagulase-negative Staphylococcus strains (CoNS) isolated from broiler chickens and to determine the occurrence of biofilm-associated genes. The biofilm production capacity of staphylococci was assessed using the microtiter plate method (MTP), and the frequency of genes was determined by PCR. The ability to form a biofilm in vitro was shown in 79.3% of examined strains. Strong biofilm capacity was demonstrated in 26.4% of strains, moderate capacity in 25.3%, weak capacity in 27.6%, and a complete lack of biofilm production capacity in 20.7% of strains. The icaAB gene responsible for the production of extracellular polysaccharide adhesins was detected in 6.9% of strains. The other four genes, i.e., bap (encoding biofilm-associated protein), atlE (encoding cell surface protein exhibiting vitronectin-binding activity), fbe (encoding fibrinogen-binding protein), and eno (encoding laminin-binding protein) were detected in 5.7%, 19.5%, 8%, and 70.1% of strains, respectively. Demonstration of genes that play a role in bacterial biofilm formation may serve as a genetic basis to distinguish between symbiotic and potentially invasive coagulase-negative staphylococcal strains

Antibiotic Resistance in Bacteria—A Review

Background: A global problem of multi-drug resistance (MDR) among bacteria is the cause of hundreds of thousands of deaths every year. In response to the significant increase of MDR bacteria, legislative measures have widely been taken to limit or eliminate the use of antibiotics, including in the form of feed additives for livestock, but also in metaphylaxis and its treatment, which was the subject of EU Regulation in 2019/6. Numerous studies have documented that bacteria use both phenotypis and gentic strategies enabling a natural defence against antibiotics and the induction of mechanisms in increasing resistance to the used antibacterial chemicals. The mechanisms presented in this review developed by the bacteria have a significant impact on reducing the ability to combat bacterial infections in humans and animals. Moreover, the high prevalence of multi-resistant strains in the environment and the ease of transmission of drug-resistance genes between the different bacterial species including commensal flora and pathogenic like foodborne pathogens (E. coli, Campylobacter spp., Enterococcus spp., Salmonella spp., Listeria spp., Staphylococcus spp.) favor the rapid spread of multi-resistance among bacteria in humans and animals. Given the global threat posed by the widespread phenomenon of multi-drug resistance among bacteria which are dangerous for humans and animals, the subject of this study is the presentation of the mechanisms of resistance in most frequent bacteria called as “foodborne pathoges” isolated from human and animals. In order to present the significance of the global problem related to multi-drug resistance among selected pathogens, especially those danger to humans, the publication also presents statistical data on the percentage range of occurrence of drug resistance among selected bacteria in various regions of the world. In addition to the phenotypic characteristics of pathogen resistance, this review also presents detailed information on the detection of drug resistance genes for specific groups of antibiotics. It should be emphasized that the manuscript also presents the results of own research i.e., Campylobacter spp., E. coli or Enetrococcus spp. This subject and the presentation of data on the risks of drug resistance among bacteria will contribute to initiating research in implementing the prevention of drug resistance and the development of alternatives for antimicrobials methods of controlling bacteria