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Manganese status,gut endogenous losses of manganese,and antioxidant enzyme activity in rats fed varying levels of manganese and fat

We hypothesized that manganese deficient animals fed high vs moderate levels of polyunsaturated fat would either manifest evidence of increased oxidative stress or would experience compensatory changes in antioxidant enzymes and/or shifts in manganese utilization that result in decreased endogenous gut manganese losses. Rats (females in Study 1, males in Study 2,n = 8/treatment) were fed diets that contained 5 or 20% corn oil by weight and either 0.01 or 1.5 μmol manganese/g diet. In study 2,⁵⁴Mn complexed to albumin was injected into the portal vein to assess gut endogenous losses of manganese. The manganese deficient rats:

In vitro TRH release from hypothalamus slices varies during the diurnal cycle

We have previously described a daily rhythm in thyrotropin releasing hormone (TRH) and TRH mRNA in the rat hypothalamus. To determine whether TRH release fluctuates in a diurnal manner, we have measured basal and potassium stimulated release from hypothalamic slices, and compared it to release from olfactory bulb slices, during the diurnal cycle. Basal TRH release was higher at 7:00 h than at any other time (1:00, 13:00 or 19:00 h) in either hypothalamus or olfactory bulb. The ratio of stimulated over basal release was higher in the hypothalamus at 19:00 h, when TRH content was highest. Potassium stimulated TRH release from olfactory bulb was not different from basal release at any time. TRH release fluctuations were not due to a rhythm of extracellular inactivation: the activity of pyroglutamyl aminopeptidase II, an ectoenzyme responsible for TRH inactivation, was constant throughout the cycle. Our data demonstrate that diurnal variations of TRH release occur in vitro and that the enhanced responsiveness to potassium stimulation in hypothalamus is correlated with increased levels of peptide.     

Particle size influences decay rates of environmental DNA in aquatic systems

Environmental DNA (eDNA) analysis is a powerful tool for remote detection of target organisms. However, obtaining quantitative and longitudinal information from eDNA data is challenging, requiring a deep understanding of eDNA ecology. Notably, if the various size components of eDNA decay at different rates, and we can separate them within a sample, their changing proportions could be used to obtain longitudinal dynamics information on targets. To test this possibility, we conducted an aquatic mesocosm experiment in which we separated fish-derived eDNA components using sequential filtration to evaluate the decay rate and changing proportion of various eDNA particle sizes over time. We then fit four alternative mathematical decay models to the data, building towards a predictive framework to interpret eDNA data from various particle sizes. We found that medium-sized particles (1–10 μm) decayed more slowly than other size classes (i.e., <1 and > 10 μm), and thus made up an increasing proportion of eDNA particles over time. We also observed distinct eDNA particle size distribution (PSD) between our Common carp and Rainbow trout samples, suggesting that target-specific assays are required to determine starting eDNA PSDs. Additionally, we found evidence that different sizes of eDNA particles do not decay independently, with particle size conversion replenishing smaller particles over time. Nonetheless, a parsimonious mathematical model where particle sizes decay independently best explained the data. Given these results, we suggest a framework to discern target distance and abundance with eDNA data by applying sequential filtration, which theoretically has both metabarcoding and single-target applications.     

Expression of wild-type GBSS transgenes in the off-spring of partially and fully complementedamylose-free transformants of potato

Theamylose-free (amf) potato mutant can easily be complemented through introduction of the wild-type gene coding for granule-bound starch synthase (GBSS). After iodine staining the starch of theamf mutant is red whereas that of the wild type and the complementedamf mutant is blue. The level of complementation of selected transformants and their sexual off-spring after backcrossing withamf was investigated using sporophytic tuber cells and gametophytic microspore cells. Two diploid and two tetraploid transformants with full complementation demonstrated the expected segregation patterns of 1:1 (one active insert) or 3:1 (two independently segregating active inserts) in the microspores and in the F1 offspring based on staining of tubers. All expected genotypes in the F1 generation were found, based on microspore segregation patterns of the individual F1 plants. Two transformants with partial complementation (mixed phenotypes) were investigated. One of them, B1, was tetraploid and duplex for the GBSS insert, which had originated through mitotic doubling of the transformed diploid cells. In the F1 generation three phenotypic classes were found:amf, fully complemented and partially complemented. The latter two classes exist independently of a simplex or duplex gene status. The second transformant with partial complementation, B10, appeared to have a complex molecular composition. One cluster of five transgenes caused the partial complementation. Fully and partially complemented phenotypic classes were found after crossing B10 with theamf mutant. Indications were found that the ploidy level of the tissue in which the genes were introduced and expressed played an important role. Firstly, partial complementation was found after transformation of the diploid and not of the tetraploidamf genotypes. Secondly, the level of complementation was higher in tissue with lower ploidy levels, as illustrated by the colour of the starch inin vitro tubers (2x–4x cells) versus field-grown tubers (16x–64x).     

Early stages of vocal ontogeny in the magpie (Pica pica)

Summary The vocal repertoire of magpie (Pica pica) chicks consists of six calls: Begging Trill (BT), Soft Whistle (SW), Begging Scream (BS), Alarm Call (AC), Distress Call (DC) and Brief Contact Note (BCN). Both BT and SW have a tonal structure and their occurrence is restricted to the nestling period. At fledging, there is a gradual change from BT into BS and a sudden appearance of harsh calls similar to those of adult birds (AC, DC, BCN), without evident transitional forms with preceding tonal calls. Both the existence and the structural design of calls seem to be adapted for providing nestlings with immediate benefits linked to the two major chapters of allocation of parental care. Emission rates of BT increase with hunger motivation under laboratory conditions. Their structure suggests that they are easily located but liable to suffer from environmental degradation. BS of fledglings may be more resistant to degradation, a trait which may facilitate the identification by parents of their own offspring. Both AC and DC attract parents to defend the nest against potential predators, and their structure make them to be easily located and detectable at long distances. BCN are given by fledglings during bouts of locomotory activity (exploration and play) and they probably help in maintaining the cohesion of the group under conditions of poor visibility. In accordance, this call may be fairly located at short distances. The function of SW was unclear. It is given during periods of nestling inactivity between begging bouts, and could be easily elicited by tactile and auditory stimuli. After laboratory experiments, it is concluded that SW serve to indicate parents that nestlings are in good condition, hence to benefit from the parental willingness to invest in a brood with high prospects of survival. Since (i) there is a widespread lack of continuity in the development of adult vocalizations starting from nestling calls, and (ii) nestling calls seem to have evolved to provide birds with benefits in the short-term, these facts argue against the prevailing idea that the main function of calls early in ontogeny is to act as precursors of adult vocalizations.

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Zusammenfassung Das Lautrepertoire von Elsternestlingen besteht aus 6 Lautäußerungen: Betteltrillern (BT), Sanftes Pfeifen (SP), Bettelkreischen (BK), Alarmruf (AR), Angstschreien (AS) und kurzer Kontaktruf (KR). BT und SP sind tonal und treten nur während der Nestlingsperiode auf. Zum Zeitpunkt des Ausfliegens geht BT graduell in BK über und plötzlich treten auch ohne vorausgehende tonale Übergangsformen rauhe Rufe ähnlich denen der Altvögel auf (AR, AS, KR). Sowohl die Existenz als auch die Struktur der Lautäußerungen scheinen als Anpassungen im Zusammenhang mit einer Optimierung der Brutpflege zu interpretieren zu sein. Die Emissionsrate von BT steigt unter Laborbedingungen mit der Hungermotivation. Die Struktur legt nahe, daß BT leicht geortet werden kann, aber auch leicht von der Umgebung verschluckt wird. BS der flüggen Jungen scheint davon weniger betroffen zu sein, so daß die Eltern leichter ihre Jungen identifizieren können. AR und AS veranlassen die Altvögel, ihr Nest gegenüber potentiellen Prädatoren zu verteidigen; die Struktur der Laute begünstigt ihre Ortung und Wahrnehmung über größere Entfernungen. KR werden von den flüggen Jungen bei lebhafter lokomotorischer Aktivität (Exploration, Spiel) geäußert; sie tragen vielleicht dazu bei, die Gruppe auch unter erschwerten optischen Kontaktmöglichkeiten zusammenzuhalten. Die Funktion von SP blieb unklar. SP war während inaktiver Perioden zwischen Bettelverhalten zu hören und konnte leicht durch taktile und akustische Reize ausgelöst werden. Nach Laborexperimenten ist zu schließen, daß SP den Eltern Wohlbefinden der Jungen anzeigt und so Bereitschaft zur Investition in eine Brut mit hoher Überlebenswahrscheinlichkeit fördert. Daß (1) zwischen den Rufen der Altvögel und dem Repertoire der Nestlingen weitgehend keine kontinuierlichen Übergänge festzustellen und (2) Nestlingsrufe offensichtlich im Hinblick auf kuzfristige Gewinne zu interpretieren sind, spricht gegen die allgemein vorherrschende Ansicht, das Lautrepertoire in frühen Stadien der Ontogenie sei hauptsächlich ein Vorläufer der Adultlaute.

     

Assessment of the lipid production potential of six benthic diatom species grown in airlift photobioreactors

Journal of Applied Phycology - In recent years diatoms have emerged as a major algal source for the production of bioactive compounds. Marine diatoms grow quickly and can store high amount of...