Penner serotyping of Campylobacter isolates from poultry, with absorbed pooled antisera

The Penner serotyping system, based on detection of heat-stable antigens with a passive haemagglutination technique, was used in studies on Campylobacter epidemiology in poultry. Preparation of specific antisera by absorption allowed the use of pooled antisera. Over 80% of the Campylobacter isolates were typable with this modified Penner serotyping system. Typability of strains was clearly affected by storage of the strains before actual typing. Extracted antigens appeared to be stable for at least 6 months at 4°C. Therefore, it is advisable to store extracted antigens from freshly isolated Campylobacter strains instead of reculturing frozen-stored strains, when actual typing cannot be performed directly after primary isolation. Untypability of isolates may partly be explained by the detection of Campylobacter serovars not yet represented in the serotyping system. Experiments on repeated serotyping of several Campylobacter strains did not suggest any serovar instability within the strains.     

Uncovering the metabolic response of abalone (<Emphasis Type="Italic">Haliotis midae)</Emphasis> to environmental hypoxia through metabolomics

Introduction

Oxygen is essential for metabolic processes and in the absence thereof alternative metabolic pathways are required for energy production, as seen in marine invertebrates like abalone. Even though hypoxia has been responsible for significant losses to the aquaculture industry, the overall metabolic adaptations of abalone in response to environmental hypoxia are as yet, not fully elucidated.

Objective

To use a multiplatform metabolomics approach to characterize the metabolic changes associated with energy production in abalone (Haliotis midae) when exposed to environmental hypoxia.

Methods

Metabolomics analysis of abalone adductor and foot muscle, left and right gill, hemolymph, and epipodial tissue samples were conducted using a multiplatform approach, which included untargeted NMR spectroscopy, untargeted and targeted LC–MS spectrometry, and untargeted and semi-targeted GC-MS spectrometric analyses.

Results

Increased levels of anaerobic end-products specific to marine animals were found which include alanopine, strombine, tauropine and octopine. These were accompanied by elevated lactate, succinate and arginine, of which the latter is a product of phosphoarginine breakdown in abalone. Primarily amino acid metabolism was affected, with carbohydrate and lipid metabolism assisting with anaerobic energy production to a lesser extent. Different tissues showed varied metabolic responses to hypoxia, with the largest metabolic changes in the adductor muscle.

Conclusions

From this investigation, it becomes evident that abalone have well-developed (yet understudied) metabolic mechanisms for surviving hypoxic periods. Furthermore, metabolomics serves as a powerful tool for investigating the altered metabolic processes in abalone.

     

Molecular evidence for the age, origin, and evolutionary history of the American desert plant genus Tiquilia (Boraginaceae)

Although the deserts of North America are of very recent origin, their characteristic arid-adapted endemic plant lineages have been suggested to be much older. Earlier researchers have hypothesized that the ancestors of many of these modern desert lineages first adapted to aridity in highly localized arid or semi-arid sites as early as the late Cretaceous or early Tertiary, and that these lineages subsequently spread and diversified as global climate became increasingly arid during the Cenozoic. No study has explicitly examined these hypotheses for any North American arid-adapted plant group. The current paper tests these hypotheses using the genus Tiquilia (Boraginaceae), a diverse North American desert plant group. A strongly supported phylogeny of the genus is estimated using combined sequence data from three chloroplast markers (matK, ndhF, and rps16) and two nuclear markers (ITS and waxy). Ages of divergence events within the genus are estimated using penalized likelihood and a molecular clock approach on the ndhF tree for Tiquilia and representative outgroups, including most of the major lineages of Boraginales. The dating analysis suggests that the stem lineage of Tiquilia split from its nearest extant relative in the Paleocene or Eocene ( approximately 59-48 Ma). This was followed by a relatively long period before the first divergence in the crown group near the Eocene/Oligocene boundary ( approximately 33-29 Ma), shortly after the greatest Cenozoic episode of rapid aridification. Divergence of seven major lineages of Tiquilia is dated to the early-to-mid Miocene ( approximately 23-13 Ma). Several major lineages show a marked increase in diversification concomitant with the onset of more widespread semi-arid and then arid conditions beginning in the late Miocene ( approximately 7 Ma). This sequence of divergence events in Tiquilia agrees well with earlier researchers' ideas concerning North American desert flora assembly.     

Pathways into childlessness: evidence of gendered life course dynamics

Using data from the first wave of the Netherlands Kinship Panel Study (NKPS) for 2867 women and 2195 men aged 40 to 79, this study examines to what extent educational, employment and marital pathways shape the likelihood of remaining childless, and whether these pathways are gendered. The findings indicate that women and men have distinctive pathways into childlessness. Educational attainment increases the likelihood of remaining childless among women only. A stable career increases the likelihood of remaining childless among women, but it increases the likelihood of entering fatherhood. Years without a partner is positively associated with childlessness among both women and men. Not having had a partnership and having had multiple partnerships are strong determinants of childlessness, especially among men.     

On the dual localization of lipoprotein lipase in rat heart. Studies with a modified perfusion technique

Rat hearts were perfused $\text{in vitro}$ using a modified $\text{Langendorff}$ technique, allowing the separate collection of coronary- and interstitial effluents. When heparin was added to the perfusion medium lipoprotein lipase was found in the coronary, as well as in the interstitial effluents. The relative amounts of lipase activity in both effluents varied with the feeding conditions of the animals, being high in the coronary effluent during fasting and high in the interstitial effluent during feeding. When glucagon (2.10^?7 M) was included in the perfusion medium, no differences between fasted and fed animals were obtained. The apparent K_m of the interstitial lipase was lower than that of the lipase found in the coronary effluent. The results are discussed in the light of the localization of lipoprotein lipase in rat hearts $\text{in situ}$.     

An individual-based model for competingDrosophila populations

An individual-based model forDrosophila is formulated, based on competition amongst larvae consuming the same batch of food. The predictions of the model are supported by data for single speciesDrosophila populations reared in the laboratory. The model is used to build a simple discrete model for the dynamics ofDrosophila populations that are kept over a number of generations. The dynamics of a single species is shown to give either a stable equilibrium or fluctuations which can be periodic or chaotic. When the dynamics of a species in the absence of the other is periodic or chaotic, we found coexistence or two alternative states, on neither of which the species can coexist.     

Microbioreactor-assisted cultivation workflows for time-efficient phenotyping of protein producing Aspergillus niger in batch and fed-batch mode

In recent years, many fungal genomes have become publicly available. In combination with novel gene editing tools, this allows for accelerated strain construction, making filamentous fungi even more interesting for the production of valuable products. However, besides their extraordinary production and secretion capacities, fungi most often exhibit challenging morphologies, which need to be screened for the best operational window. Thereby, combining genetic diversity with various environmental parameters results in a large parameter space, creating a strong demand for time-efficient phenotyping technologies. Microbioreactor systems, which have been well established for bacterial organisms, enable an increased cultivation throughput via parallelization and miniaturization, as well as enhanced process insight via non-invasive online monitoring. Nevertheless, only few reports about microtiter plate cultivation for filamentous fungi in general and even less with online monitoring exist in literature. Moreover, screening under batch conditions in microscale, when a fed-batch process is performed in large-scale might even lead to the wrong identification of optimized parameters. Therefore, in this study a novel workflow for Aspergillus niger was developed, allowing for up to 48 parallel microbioreactor cultivations in batch as well as fed-batch mode. This workflow was validated against lab-scale bioreactor cultivations to proof scalability. With the optimized cultivation protocol, three different micro-scale fed-batch strategies were tested to identify the best protein production conditions for intracellular model product GFP. Subsequently, the best feeding strategy was again validated in a lab-scale bioreactor.     

Two new species and a new subgenus of toothed Brachyhypopomus electric knifefishes (Gymnotiformes,Hypopomidae) from the central Amazon and considerations pertaining to the evolution of a monophasic electric organ discharge

We describe two new, closely related species of toothed Brachyhypopomus (Hypopomidae: Gymnotiformes: Teleostei) from the central Amazon basin and create a new subgenus for them. Odontohypopomus, new subgenus of Brachyhypopomus, is diagnosed by (1) small teeth present on premaxillae; (2) medialmost two branchiostegal rays thin with blades oriented more vertically than remaining three rays; (3) background color in life (and to lesser extent in preservation) distinctly yellowish with head and sides peppered with small, widely spaced, very dark brown stellate chromatophores that greatly contrast with light background coloration; (4) a dark blotch or bar of subcutaneous pigment below the eye; (5) electric organ discharge waveform of very long duration (head-positive phase approx. 2 milliseconds or longer, head-negative phase shorter or absent) and slow pulse repetition rate (3–16 Hz). The type species of the new subgenus, Brachyhypopomus (Odontohypopomus) walteri sp. n., is diagnosed by the following additional character states: (1) subcutaneous dark pigment at base of orbit particularly prominent, (2) body semi-translucent and nearly bright yellow background coloration in life, (3) a biphasic electric organ discharge (EOD) waveform of very long duration (between 3.5 and 4 milliseconds at 25° C) with head-positive first phase significantly longer than second head-negative phase in both sexes. Brachyhypopomus (Odontohypopomus) bennetti sp. n. is diagnosed by two character states in addition to those used to diagnose the subgenus Odontohypopomus: (1) a deep electric organ, visible as large semi-transparent area, occupying approximately 14–17% body depth directly posterior to the abdominal cavity in combination with a short, but deep, caudal filament, and (2) a monophasic, head-positive EOD waveform, approximately 2.1 milliseconds in duration in both sexes. These are the only described rhamphichthyoid gymnotiforms with oral teeth, and Brachyhypopomus bennetti is the first Brachyhypopomus reported to have a monophasic (head-positive) EOD waveform. Unlike biphasic species, the waveform of its EOD is largely unaffected by tail damage from predators. Such injuries are common among specimens in our collections. This species’ preference for floating meadow habitat along the major channels of the Amazon River basin may put it at particularly high risk of predation and “tail grazing.”     

Quality of core collections for effective utilisation of genetic resources review, discussion and interpretation

Definition of clear criteria for evaluation of the quality of core collections is a prerequisite for selecting high-quality cores. However, a critical examination of the different methods used in literature, for evaluating the quality of core collections, shows that there are no clear guidelines on the choices of quality evaluation criteria and as a result, inappropriate analyses are sometimes made leading to false conclusions being drawn regarding the quality of core collections and the methods to select such core collections. The choice of criteria for evaluating core collections appears to be based mainly on the fact that those criteria have been used in earlier publications rather than on the actual objectives of the core collection. In this study, we provide insight into different criteria used for evaluating core collections. We also discussed different types of core collections and related each type of core collection to their respective evaluation criteria. Two new criteria based on genetic distance are introduced. The consequences of the different evaluation criteria are illustrated using simulated and experimental data. We strongly recommend the use of the distance-based criteria since they not only allow the simultaneous evaluation of all variables describing the accessions, but they also provide intuitive and interpretable criteria, as compared with the univariate criteria generally used for the evaluation of core collections. Our findings will provide genebank curators and researchers with possibilities to make informed choices when creating, comparing and using core collections.