Does the combination of embryonic diapause and superfoetation occur in the stoat Mustela erminea? A reinterpretation of existing data

Superfoetation is when ovulation and fertilisation occur during pregnancy. Coupled with embryonic diapause, superfoetation presents an intriguing female reproductive advantage in terms of cryptic choice of males. Unfortunately, few studies have identified species possessing both superfoetation and embryonic diapause. We aim to reinterpret existing data on reproductive physiology in the stoat Mustela erminea and suggest it may be a previously overlooked species that possesses this combination. By increasing our knowledge of such reproductive systems, we can further our understanding of a cryptic sexually selected function and better explain the evolutionary gain and loss of embryonic diapause in mammals.     

Tracking leatherback turtles (Dermochelys coriacea) during consecutive inter-nesting intervals: Further support for direct transmitter attachment

Over recent years there have been substantial efforts to record and interpret the post-nesting movements of leatherback turtles (Dermochelys coriacea) breeding in tropical regions. Less well documented are the movements undertaken by individual turtles during the breeding season itself, or more specifically between sequential nesting events. Such movements are of interest for two reasons: (1) gravid female leatherbacks may range extensively into the territorial waters and nesting beaches of neighbouring countries, raising questions for conservationists and population ecologists; and (2) the magnitude of movements themselves help elucidate underlying reproductive strategies (e.g. whether to rest near to the nesting or forage extensively). Here, satellite relay data loggers are used (SRDLs) to detail the movements and behaviour of two female leatherback turtles throughout three consecutive inter-nesting intervals in the Commonwealth of Dominica, West Indies. Both near-shore residence and extensive inter-nesting movements were recorded, contrasting previous studies, with movements away from the nesting beach increasing towards the end of the nesting season. Using this behavioural study as a backdrop, the suitability of attaching satellite transmitters directly to the carapace was additionally explored as an alternative approach to conventional harness deployments. Specifically, the principal aims were to (1) gather empirical data on speed of travel and (2) assess dive performance (aerobic dive limit) to enable comparisons with turtles previously fitted with harnesses elsewhere in the Caribbean (n = 6 turtles; Grenada, WI). This produced mixed results with animals bearing directly attached transmitters travelling significantly faster (55.21 km day^− 1; SD 6.68) than harnessed individuals (39.80 km day^− 1; SD 6.19); whilst no discernable difference in dive performance could be found between the two groups of study animals.     

Anterior adhesive areas and adjacent secretions in the parasitic flatworms Decacotyle lymmae and D. tetrakordyle (Monogenea: Monocotylidae) from the gills of stingrays

Abstract. The monogeneans Decacotyle lymmae and D. tetrakordyle (Monocotylidae: Decacotylinae), from gills of the dasyatid stingrays Taeniura lymma and Pastinachus sephen , respectively, have a single aperture for adhesive secretion on each side of the anterior ventrolateral region. Rod-shaped bodies (S1) and electron-dense spherical secretion (S2) exit through specialised ducts opening adjacent to one another within these apertures. The S1 bodies are 230 ± 11 nm wide and ≥4 μm long in D. lymmae and 240 ± 9 nm wide and ≥3.3 μm long in D. tetrakordyle . The S2 bodies have a diameter of 88 ± 7 nm in D. lymmae and 65 ± 6 nm in D. tetrakordyle . The apertures are unusual in being extremely small (internal diameter, 3–5 μm). Each aperture has a slit-like surface opening as small as 160 nm wide, surrounded by muscle fibres indicating that they may be opened and closed. The aperture is also surrounded and underlain by muscle fibres that may aid in secretion from, or even eversion of, the tissue within the aperture. Sensilla/cilia are also found within the apertures. Additional secretions from anteromedian and anterolateral glands (body glands), each containing granular secretions, occur in profusion and exit anteriorly and posteriorly to the position of the apertures, through duct openings in the general body tegument. These granular secretions do not appear to be associated with anterior adhesion. Both species show similarities in aperture, underlying tissue, sense organ, and secretion detail, in accordance with findings from other monogenean genera, and which supports the importance of such data for phylogenetic studies.     

Deposition of bacterial cells onto glass and biofilm surfaces

Deposition rates of Pseudomonas putida and Hyphomicrobium ZV620 onto glass and biofilm surfaces were quantified. Both species deposited to glass at a much slower rate than to biofilm. A definite bias by depositing cells for biofilms of their own species was evident in the highest attachment rates observed in this study.     

Energized membrane may regulate nucleoid conformation in Bacillus subtilis

Abstract It was shown in a previous study, using a temperature-sensitive initiation mutant of Bacillus subtilis that DNA synthesis at the origin and terminus of replication occurred at cell poles. In the current study, it is demonstrated that cells specifically labelled at the origin or near the terminus, show a re-distribution of radioactivity when treated with the uncoupling agent, sodium azide. Since it is most likely that the DNA-cell wall attachment is mediated through membrane interactions, we now propose that the maintenance of this attachment is dependent on the energized state of the membrane.     

Pre-infection events in non-nodulating species of African Acacia

Non-nodulation occurs sporadically throughout the family Leguminosae, the genus Acacia is unusual as there are a range of species which are consistently non-nodulating, but which are closely related to species able to form nodules. A comparative study of these and coexisting related nodulating species has been made to establish whether the non-nodulating species exhibited any pre-infection characteristics which are typical of their nodulating counterparts. The non-nodulating species did not form any nodule-like structures, but exhibited pre-infection characteristics such as rhizobial attachment similar to that of their nodulating counterparts. The root exudate of nodulating A. polyacantha contained stimulatory compounds which aided binding of rhizobia to the roots of the non-nodulating species and nodulation was completely inhibited when A. polyacantha was co-cultured with a non-nodulating species.     

Coupling exo- and endocytosis: An essential role for PIP2 at the synapse

Chemical synapses are specialist points of contact between two neurons, where information transfer takes place. Communication occurs through the release of neurotransmitter substances from small synaptic vesicles in the presynaptic terminal, which fuse with the presynaptic plasma membrane in response to neuronal stimulation. However, as neurons in the central nervous system typically only possess ~ 200 vesicles, high levels of release would quickly lead to a depletion in the number of vesicles, as well as leading to an increase in the area of the presynaptic plasma membrane (and possible misalignment with postsynaptic structures). Hence, synaptic vesicle fusion is tightly coupled to a local recycling of synaptic vesicles. For a long time, however, the exact molecular mechanisms coupling fusion and subsequent recycling remained unclear. Recent work now indicates a unique role for the plasma membrane lipid phosphatidylinositol 4,5-bisphosphate (PIP₂), acting together with the vesicular protein synaptotagmin, in coupling these two processes. In this work, we review the evidence for such a mechanism and discuss both the possible advantages and disadvantages for vesicle recycling (and hence signal transduction) in the nervous system. This article is part of a Special Issue entitled Lipids and Vesicular Transport.     

Upregulation of Toll-like receptor 4 through anti-miR-Let-7a enhances blastocyst attachment to endometrial cells in mice

Despite encouraging advances in fertility technology, the success rate of an ongoing pregnancy is relatively low and predominantly associated with implantation failure. Inflammatory responses are beneficial in the fetomaternal interface and supposedly accelerate the chances for successful implantation. The current study aims to determine the effect of Toll-like receptor 4 (TLR4) overexpression in mouse blastocysts via Let-7a downregulation using intracytoplasmic sperm injection-sperm-mediated gene transfer on embryo attachment rate. The pLenti-III-GFP-miR-Off-Let-7a vector was transmitted to oocytes derived via in vitro maturation (IVM) and in vivo oocytes by using NaOH-treated spermatozoa. Let-7a and TLR4 expression levels were evaluated by quantitative real-time polymerase chain reaction (qRT-PCR), immunocytochemistry, and western blot analysis in both oocytes and embryos. Blastocyst adhesion on the endometrial cells was monitored by microscopic analysis. qRT-PCR results showed that Let-7a expression decreased in the IVM (GV-MII) oocytes compared to the in vivo oocyte (MII) group (p < .05). TLR4 showed a higher expression in GV-MII oocytes at both the gene and protein levels (p < .05). Following anti-miR-Let-7a transmission, the TLR4 expression level was significantly upregulated in embryos compared with the control groups (p < .05). Attachment and migration of trophoblasts cells towards endometrial cells dramatically increased compared to the control group (p < .05). Based on our results, we concluded that Let-7a might mediate embryo attachment through regulation of TLR4 expression levels.     

Influence of nanophase titania topography on bacterial attachment and metabolism

Surfaces with nanophase compared to conventional (or nanometer smooth) topographies are known to have different properties of area, charge, and reactivity. Previously published research indicates that the attachment of certain bacteria (such as Pseudomonas fluorescens 5RL) is higher on surfaces with nanophase compared to conventional topographies, however, their effect on bacterial metabolism is unclear. Results presented here show that the adhesion of Pseudomonas fluorescens 5RL and Pseudomonas putida TVA8 was higher on nanophase than conventional titania. Importantly, in terms of metabolism, bacteria attached to the nanophase surfaces had higher bioluminescence rates than on the conventional surfaces under all nutrient conditions. Thus, the results from this study show greater select bacterial metabolism on nanometer than conventional topographies, critical results with strong consequences for the design of improved biosensors for bacteria detection.