From the Schnauzenorgan to the back: Morphological comparison of mormyromast electroreceptor organs at different skin regions of Gnathonemus petersii

The nocturnally active weakly electric fish Gnathonemus petersii is known to employ active electrolocation for the detection of objects and for orientation in its environment. The fish emits pulse‐type electric signals with an electric organ and perceives these signals with more than 3,000 epidermal electroreceptor organs, the mormyromasts, which are distributed over the animal's skin surface. In this study, we measured the metric dimensions of the mormyromasts from different body regions to find structural and functional specialization of the various body parts. We focused on the two foveal regions of G. petersii, which are located at the elongated and movable chin (the Schnauzenorgan; SO) and at the nasal region (NR), the skin region between the mouth and the nares. These two foveal regions were compared to the dorsal part (back) of the fish, which contains typical nonfoveal mormyromasts. While the gross anatomy of the mormyromasts from all skin regions is similar, the metric dimensions of the main substructures differed. The mormyromasts at the SO are the smallest and contain the smallest receptor cells. In addition, the number of receptor cells per organ is lowest at the SO. In contrast, at the back the biggest receptor organs with the highest amount of receptor cells per organ occur. The mormyromasts at the NR are in several respects intermediate between those from the back and the SO. However, mormyromasts at the NR are longer than those at all other skin regions, the canal leading from the receptor pore to the inner chambers were the longest and the overlaying epidermal layers are the thickest. These results show that mormyromasts and the epidermis they are embedded in at both foveal regions differ specifically from those found on the rest of the body. The morphological specializations lead to functional specialization of the two foveae. J. Morphol., 2012. © 2012 Wiley Periodicals, Inc.     

In situ hybridization study of chromogranin A and B mRNA in carcinoid tumors

Summary The distribution of the mRNAs for chromogranin A and B was analyzed by in situ hybridization with ³⁵S-labeled oligonucleotide probes in formalin-fixed paraffin-embedded carcinoid tumor tissues. All the 15 mid-gut carcinoid tumors examined contained both mRNAs for chromogranin A and B at high level in tumor cells. Sixteen of 18 bronchial carcinoid tumors but only 2 of 5 rectal carcinoid tumors expressed one or both species of chromogranin mRNAs. The same tendency was seen with the argyrophil reaction according to Grimelius where most of the mid-gut tumor cells were uniformly stained, while considerable variation in reactivity was seen in some of the bronchial and rectal carcinoid tumor cells. The sequential sections were stained with a monoclonal antibody against chromogranin A and a polyclonal antiserum which reacts with both chromogranins. The expression of the mRNA for chromogranin A on the carcinoid tumors was almost concordant with that of chromogranin B as well as with the chromogranin A protein, whereas almost all tumors stained positively with the polyclonal antibodies. Analyses of mRNA expression of chromogranin A before and after interferon therapy on 4 patients with mid-gut carcinoids indicated an inhibition at pre-translational level. In conclusion, the mRNAs for chromogranin A and B are good markers for the carcinoid tumors, especially of mid-gut origin. Fore-gut, mid-gut and rectal carcinoid tumors are different in their endocrine properties regarding the expression of the chromogranins.     

Evolution of avian eggshell structure

Data are presented suggesting that birds have evolved eggs with shells containing different structures (numbers of mammillae per unit of inner eggshell surface area, i.e., mammillary densities) to cope up with different calcium requirements imposed by different growth rates and modes of development. Precocial bird species grow slowly, but have high mammillary density, while altricial bird species grow rapidly, but have low mammillary density. These results suggest an adaptation associated with growth rate and mode of development and show, moreover, that the mammillary layer is indicative of the breeding biology of the bird. J. Morphol. 2012. © 2011 Wiley Periodicals, Inc.     

Head width–body mass equation: facilitating worker termite biomass estimates

1. Termites are one of the most important invertebrate ecosystem engineers in tropical regions, which may be quantified using termite biomass data. However, biomass data are particularly difficult to collect as they rely on termites being weighed in the field, which may neither be possible nor convenient. Local scale linear regression models, based on termite head widths (mm) and body masses (mg), have been used in the past to estimate termite biomass using head width and abundance data. However, these models represent very limited numbers of termite taxa from single sites. In the present study, I provide one of the most representative linear regression models available based on 90 samples from three different countries (Peru, Kenya, and Malaysia). 2. Although the linear regression model under‐ or overestimated body weights of taxa with characteristic features (e.g. large heads of Odontotermes workers or elongated abdomens of Kalotermitidae) it provides a robust method for estimating termite biomass at the community level. Additionally, while there are limitations related to the general model, which may be solved by focusing on taxa specific data and the use of higher accuracy equipment, it is the first model to facilitate termite biomass estimates using the head with and abundance data only. 3. This study encourages the use of termite biomass data to gain a better understanding of termites in ecosystem processes and calls for comparative data to be gathered for the purpose of creating models that may be representative of the variability among termite taxa.     

Biodiversity and ecosystem functioning: It is time for dispersal experiments

The experimental study of the relationship between biodiversity and ecosystem function has mainly addressed the effect of species and number of functional groups. In theory, this approach has mainly focused on how extinction affects function, whereas dispersal limitation of ecosystem function has been rarely discussed. A handful of seed introduction experiments, as well as numerous observations of the effects of long‐distance dispersal of alien species, indicate that ecosystem function may be strongly determined by dispersal limitation at the local, regional and/or global scales. We suggest that it is time to replace biodiversity manipulation experiments, based on random draw of species, with those addressing realistic scenarios of either extinction or dispersal. Experiments disentangling the dispersal limitation of ecosystem function should have to take into account the probability of arrival. The latter is defined as the probability that a propagule of a particular species will arrive at a particular community. Arrival probability depends on the dispersal ability and the number of propagules of a species, the distance a species needs to travel, and the permeability of the matrix landscape. Current databases, in particular those in northwestern and central Europe now enable robust estimation of arrival probability in plant communities. We suggest a general hypothesis claiming that dispersal limitation according to arrival probability will have ecosystem‐level effects different from those arising due to random arrival. This hypothesis may be rendered more region‐, landscape‐ or ecosystem‐specific by estimating arrival probabilities for different background conditions.     

Body size but not colony size increases with altitude in the holarctic ant,Leptothorax acervorum

1. Bergmann's rule states that organisms inhabiting colder environments show an increase in body size or mass in comparison to their conspecifics living in warmer climates. Although originally proposed for homoeothermic vertebrates, this rule was later extended to ectotherms. In social insects, only a few studies have tested this rule and the results were ambiguous. Here, ‘body size’ can be considered at two different levels (the size of the individual workers or the size of the colony). 2. In this study, data from 53 nests collected along altitudinal gradients in the Alps were used to test the hypotheses that the worker body size and colony size of the ant Leptothorax acervorum increase with increasing altitude and therefore follow Bergmann's rule. 3. The results show that the body size of workers but not the colony size increases with altitude. Whether this pattern is driven by starvation resistance or other mechanisms remains to be investigated.     

Effect of micro-aeration on anaerobic digestion of primary sludge under septic tank conditions

Micro-aeration, which refers to the addition of very small amounts of air, is a simple technology that can potentially be incorporated in septic tanks to improve the digestion performance. The purpose of this study was to investigate and compare the effects of micro-aeration on anaerobic digestion of primary sludge under septic tank conditions. 1.6 L batch reactor experiments were carried out in duplicate using raw primary sludge, with 4.1 % total solids, and diluted primary sludge, with 2.1 % total solids. Reactors were operated for 5 weeks at room temperature to simulate septic tank conditions. Micro-aeration rate of 0.00156 vvm effectively solubilised chemical oxygen demand (COD) and improved the subsequent degradation of COD. Micro-aeration also increased the generation of ammonia and soluble proteins, but did not improve the reduction in total and volatile solids, or the reduction in carbohydrates. Experiments using diluted sludge samples showed similar trends as the experiments with raw sludge, which suggest that initial solids concentration did not have a significant effect on the degradation of primary sludge under septic tank conditions.     

Production of the lepidoptera-specific crystal protein by a local isolate of Bacillus thuringiensis

Summary A local isolate of Bacillus thuringiensis (B.t.81) produced crystal protein which was identified as a cry I gene of Class I. The synthesis and assembly of crystal complements were investigated at intervals throughout the growth cycle. Incubation temperature had a marked effect on toxin synthesis; production being the highest at 25°C and the lowest at 42°C. The mutants of B. t. 81, unable to synthesize crystal protein complements, have also been described.