Fighting by Kittens and Piglets during Suckling: What Does it Mean?

Newborn kittens and piglets show some notable similarities in suckling‐associated behaviours. Both develop a pattern of teat use in which each member of the litter predominantly occupies one or two particular nipples or teats, both show agonistic behaviour towards littermates during suckling, and both are born with ‘weapons’–kittens with sharp claws and piglets with sharp needle teeth. Traditionally, the differential use of nipples or teats has been thought to be due to differential quality of the mammary glands. However, neither our findings in kittens nor an examination of the literature on piglets support this view. As mammary glands usually are of equal quality and as there are normally more glands than young, there seems little reason for littermates to fight. Furthermore, there is also little evidence that individual performance in suckling contests or use of ‘weapons’ is related to weight gain or to dominance relations. Given the present lack of satisfying adaptive explanations for the seemingly aggressive behaviour and use of weapons by kittens and piglets, we suggest these to be epiphenomena of developmental processes anticipating the use of these behaviours and structures in later adaptive contexts.     

Sebastiano Genovese: In Memoriam

Abstract

Laboratory simulations have helped resolve several problems concerning the role of bacteria in producing acidic drainage from active and abandoned coal mines. It is well established that the bacterium Thiobacillus ferrooxidans oxidizes pyrite in synthetic liquid media and in flooded or agitated experimental simulations of coal mine environments. However, many geologists remain skeptical regarding the role of T. ferrooxidans in producing acidity below a near‐surface belt of soil water. We have demonstrated that T. ferrooxidans is capable of colonizing and acidifying a near‐neutral pH environment of crushed coal or overburden, without prior establishment of a pH‐dependent succession of bacteria. We have suggested that T. ferrooxidans may accomplish this by direct oxidation of pyrite. We have also shown that T. ferrooxidans catalyzes pyrite oxidation in the intermediate belt of the zone of aeration, although only for a limited period of time after rainfall infiltration. T. ferrooxidans was not found to be significant in the simulated zone of groundwater saturation.     

Rat model of fractionated (2 Gy/day) 60 Gy irradiation of the liver: long-term effects

The liver is considered a radiosensitive organ. However, in rats, high single-dose irradiation (HDI) showed only mild effects. Consequences of fractionated irradiation (FI) in such an animal model have not been studied so far. Rats were exposed to selective liver FI (total dose 60 Gy, 2 Gy/day) or HDI (25 Gy) and were killed three months after the end of irradiation. To study acute effects, HDI-treated rats were additionally killed at several time points between 1 and 48 h. Three months after irradiation, no differences between FI and HDI treatment were found for macroscopically detectable small “scars” on the liver surface and for an increased number of neutrophil granulocytes distributed in the portal fields and through the liver parenchyma. As well, no changes in HE-stained tissues or clear signs of fibrosis were found around the portal vessels. Differences were seen for the number of bile ducts being increased in FI- but not in HDI-treated livers. Serum levels indicative of liver damage were determined for alkaline phosphatase (AP), aspartate aminotransferase (AST), alanine aminotransferase (ALT), gamma-glutamyltransferase (γGT) and lactate dehydrogenase (LDH). A significant increase of AP was detected only after FI while HDI led to the significant increases of AST and LDH serum levels. By performing RT-PCR, we detected up-regulation of matrix metalloproteinases, MMP-2, MMP-9, MMP-14, and of their inhibitors, TIMP-1, TIMP-2 and TIMP-3, shortly after HDI, but not at 3 month after FI or HDI. Overall, we saw punctual differences after FI and HDI, and a diffuse formation of small scars at the liver surface. Lack of “provisional clot”-formation and absence of recruitment of mononuclear phagocytes could be one explanation for scar formation as incomplete repair response to irradiation.     

Reassessment of cf. Halticosaurus orbitoangulatus from the Upper Triassic (Norian) of Germany – a pseudosuchian,not a dinosaur

The holotype of cf. Halticosaurus orbitoangulatus Huene, 1932, comprises an incomplete and macerated but associated skull of an archosaurian reptile from the middle (second) Stubensandstein (middle Löwenstein Formation; Upper Triassic: Norian) of Baden‐Württemberg, Germany. It was originally interpreted as a theropod dinosaur but more recently it has been suggested that this taxon has crocodylomorph affinities. Detailed preparation of the holotype of cf. H. orbitoangulatus has revealed much new anatomical information and permitted reassessment of its affinities. The maxilla lacks both a distinct antorbital fossa and a medial bony lamina bordering the antorbital fenestra. The lateral surface of the dentary bears a pronounced horizontal ridge. The squamosal differs from that of basal crocodylomorphs in being L‐shaped rather than arcuate in dorsal view, lacking a dorsolateral overhang, and lacking an interlocking contact with the paroccipital process as, for example, in the basal crocodylomorph Saltoposuchus connectens from the same horizon and locality. Phylogenetic analysis placed cf. H. orbitoangulatus amongst loricatan pseudosuchians (but not amongst Crocodylomorpha) rather than amongst theropod dinosaurs. The holotype of cf. H. orbitoangulatus represents a previously unrecognized taxon of loricatan pseudosuchian, which is here named Apatosuchus orbitoangulatus and set apart from other known Norian‐age non‐crocodylomorph loricatans by its apparently much smaller size. © 2013 The Linnean Society of London     

Shift Work and Inter‐Individual Differences in Sleep and Sleepiness

Inter‐individual differences in tolerance for shift work have been studied primarily in terms of external factors affecting alertness on the job or the ability to rest and sleep while at home. However, there is increasing evidence that neurobiological factors play a role as well, particularly the major processes involved in the regulation of sleep and wakefulness. These include a sleep homeostatic process seeking to balance wakefulness and sleep and a circadian process seeking to promote wakefulness during the day and sleep during the night. Shift work is associated with a temporal misalignment of these two endogenous processes. During nightwork, this misalignment makes it difficult to stay awake during the nightshift and sleep during the day. However, inter‐individual variability in the processes involved in sleep/wake regulation is substantial. Recent studies have demonstrated the existence of inter‐individual differences in vulnerability to cognitive deficits from sleep loss. Moreover, these inter‐individual differences were shown to constitute a trait. Interestingly, self‐evaluations of sleepiness did not correspond well with the trait inter‐individual variability in objective levels of performance impairment during sleep deprivation. Perhaps because of this discrepancy, in operational settings, the inter‐individual differences in vulnerability to sleep loss do not appear to be limited due to self‐selection mechanisms. Indeed, even among a highly select group of active‐duty jet fighter pilots flying a series of simulated night missions, systematic inter‐individual differences in performance impairment from sleep loss were still observed. There are significant personal and economic consequences to human error and accidents caused by performance deficits due to sleep loss. It is important, therefore, to study the inter‐individual differences in the regulation of sleep and wakefulness in the work environment so that cognitive impairment during shift work may be better anticipated and prevented.     

Heterometallic [AgFe3S4] ferredoxin variants: synthesis, characterization, and the first crystal structure of an engineered heterometallic iron–sulfur protein

Heterometallic [AgFe₃S₄] iron–sulfur clusters assembled in wild-type Pyrococcus furiosus ferredoxin and two variants, D14C and D14H, are characterized. The crystal structure of the [AgFe₃S₄] D14C variant shows that the silver(I) ion is indeed part of the cluster and is coordinated to the thiolate group of residue 14. Cyclic voltammetry shows one redox pair with a reduction potential of +220 mV versus the standard hydrogen electrode which is assigned to the [AgFe₃S₄]^2+/+ couple. The oxidized form of the [AgFe₃S₄] D14C variant is stable in the presence of dioxygen, whereas the oxidized forms of the [AgFe₃S₄] wild type and D14H variants convert to the [Fe₃S₄] ferredoxin form. The monovalent d ¹⁰ silver(I) ion stabilizes the [Fe₃S₄]^+/0 cluster fragment, as opposed to divalent d ¹⁰ metal ions, resulting in more than 0.4 V difference in reduction potentials between the silver(I) and, e.g., zinc(II) heterometallic [MFe₃S₄] ferredoxins. The trend in reduction potentials for the variants containing the [AgFe₃S₄] cluster is wild type ≤ D14C < D14H and shows the same trend as reported for the variants containing the [Fe₃S₄] cluster, but is different from the D14C < D14H < wild type trend reported for the [Fe₄S₄] ferredoxin. The similarity in the reduction potential trend for the variants containing the heterometallic [AgFe₃S₄] cluster and the [Fe₃S₄] cluster can be rationalized in terms of the electrostatic influence of the residue 14 side chains, rather than the dissociation constant of this residue, as is the case for [Fe₄S₄] ferredoxins. The trends in reduction potentials are in line with there being no electronic coupling between the silver(I) ion and the Fe₃S₄ fragment.     

Histological and Micro-CT Evidence of Stigmatic Rostellum Receptivity Promoting Auto-Pollination in the Madagascan Orchid Bulbophyllum bicoloratum

Background

The rostellum, a projecting part of the gynostemium in orchid flowers, separates the anther(s) from the stigma and thus commonly prevents auto-pollination. Nonetheless, as a modified (usually distal) portion of the median stigma lobe, the rostellum has been frequently invoked of having re-gained a stigmatic function in rare cases of orchid auto-pollination. Here it is shown that a newly discovered selfing variant of Madagascan Bulbophyllum bicoloratum has evolved a modified rostellum allowing the penetration of pollen tubes from in situ pollinia.

Methods

Gynostemium micro-morphology and anatomy of selfing and outcrossing variants of B . bicoloratum was studied by using light and scanning electron microscopy and histological sections. Pollen tube growth in the selfing variant was further observed via X-ray computed microtomography (micro-CT), providing 3D reconstructions of floral tissues at a micron scale.

Findings

Selfing variants possess a suberect (‘displaced’) rostellum rather than the conventional, erect type. Very early in anthesis, the pollinia of selfers are released from the anther and slide down onto the suberect rostellum, where pollen tube growth preferentially occurs through the non-vascularized, i.e. rear (adaxial) and (semi-) lateral parts. This penetrated tissue is comprised of a thin layer of elongate and loosely arranged cells, embedded in stigmatic exudates, as also observed in the stigmatic cavity of both selfing and outcrossing variants.

Conclusions

Our results provide the first solid evidence of a stigmatic function for the rostellum in orchid flowers, thereby demonstrating for the first time the feasibility of the micro-CT technique for accurately visualizing pollen tube growth in flowering plants. Rostellum receptivity in B . bicoloratum probably uniquely evolved as an adaptation for reproductive assurance from an outcrossing ancestor possessing an erect (non-receptive) rostellum. These findings open up new avenues in the investigation of an organ that apparently re-gained its ‘primordial function’ of being penetrated by pollen tubes.