A Spatially Explicit Model of Synchronization in Fiddler Crab Waving Displays

Fiddler crabs (Uca spp., Decapoda: Ocypodidae) are commonly found forming large aggregations in intertidal zones, where they perform rhythmic waving displays with their greatly enlarged claws. While performing these displays, fiddler crabs often synchronize their behavior with neighboring males, forming the only known synchronized visual courtship displays involving reflected light and moving body parts. Despite being one of the most conspicuous aspects of fiddler crab behavior, little is known about the mechanisms underlying synchronization of male displays. In this study we develop a spatially explicit model of fiddler crab waving displays using coupled logistic map equations. We explored two alternative models in which males either direct their attention at random angles or preferentially toward neighbors. Our results indicate that synchronization is possible over a fairly large region of parameter space. Moreover, our model was capable of generating local synchronization neighborhoods, as commonly observed in fiddler crabs under natural conditions.     

A case-control study on selenium,zinc, and copper in plasma and hair of subjects affected by breast and lung cancer

The purpose of our study was to investigate the relationship between plasma and hair levels of Se, Zn, and Cu, and cancer. We selected a total of 66 patients affected by either breast (38) or lung (28) cancer. They entered into the study at the onset of disease, and before any chemical or radiotherapy. Controls were randomly selected among healthy people and were matched for sex, age, smoking habits, and residence. In the group of breast cancer, a significant decrease in hair Se was found compared to controls (p<0.01), whereas plasma Se was only slightly decreased. No difference between cases and controls was detected in both hair and plasma levels of Zn and Cu. Subjects who developed lung cancer were significantly lower in hair Zn (p<0.05) and Cu (p<0.01) than controls, whereas there was no difference with regard to Se. In addition, plasma Cu of these patients was increased as compared to controls.     

Opa-like repeats in the genome of the Medfly Ceratitis capitata

The sequence determination of several genomic clones isolated from the Mediterranean fruitfly Ceratitis capitata identified the existence of opa-like repeats, often more than one being clustered in small chromosomal segments. These repeats have previously been shown to consist of stretches of tandemly reiterated glutamine-encoding residues, and they are found in multiple genes of several organisms. Most of the repeats described here are flanked or interrupted by stop codons in all reading frames and, thus, could not possibly be part of protein-coding sequences. Furthermore, these repeats, of which there are several hundred in the genome of the Medfly, can be used effectively for the determination of sequence polymorphisms, providing a convenient approach to obtain additional landmarks for the construction of genomic maps of this economically important insect.This paper is dedicated to the memory of our colleague and friend Dr. Jim Flach who took part in the initial phase of this work and died during the course of the investigation.     

Purified angiotensin converting enzyme from Rana esculenta ovary influences ovarian steroidogenesis in vitro

The aim of the present study was to purify and characterize angiotensin-converting enzyme (ACE) present in frog ovary (Rana esculenta). Detergent and trypsin-extracted enzymes were purified using a one-step process, consisting of affinity chromatography on lisinopril coupled to Sepharose 6B. The molecular mass was 150 kDa for both detergent-extracted and trypsin-extracted enzyme. The specific activity of detergent-extracted and trypsin-extracted ACE was 294 U mg(-1) and 326 U mg(-1) respectively. The optimum pH range was from 7-8.5 at 37 degrees C and the optimum temperature was 50 degrees C. Optimum chloride concentration was about 200 mM for synthetic substrate FAPGG (N-[3-(2-furyl)acryloyl] L-phenylalanyl glycyl glycine) and angiotensin I, and 10 mM for bradykinin. The Km and Kcat values for FAPGG were 0.608 +/- 0.07 mM and 249 sec(-1) respectively and I50 values for captopril and lisinopril, two specific ACE inhibitors, were 68 +/- 12.55 nM and 6.763 +/- 0.66 nM respectively. Frog ovary tissue from prereproductive period was incubated in vitro in the presence of frog ovary ACE (2.5 mU/ml), captopril (0.1 mM), and lisinopril (0.1 mM). Production of 17beta-estradiol, progesterone, and prostaglandins E2 and F2alpha was determined. The data showed a modulation of 17beta-estradiol, progesterone and prostaglandin E2 production by ovary ACE.     

Low-spin sulfite reductases: a new homologous group of non-heme iron-siroheme proteins in anaerobic bacteria

Two new low molecular weight proteins with sulfite reductase activity, isolated from Methanosarcina barkeri (DSM 800) and Desulfuromonas acetoxidans (strain 5071), were studied by EPR and optical spectroscopic techniques. Both proteins have visible spectra similar to that of the low-spin sulfite reductase of Desulfovibrio vulgaris strain Hildenborough and no band at 715 nm, characteristic of high-spin Fe3+ complexes in isobacteriochlorins is observed. EPR shows that as isolated the siroheme is in a low-spin ferric state (S = 1/2) with g-values at 2.40, 2.30 and 1.88 for the Methanosarcina barkeri enzyme and g-values at 2.44, 2.33 and 1.81 for the Desulfuromonas acetoxidans enzyme. Chemical analysis shows that both proteins contain one siroheme and one [Fe4S4] center per polypeptidic chain. These results suggest that the low molecular weight, low-spin non-heme iron siroheme proteins represent a new homologous class of sulfite reductases common to anaerobic microorganisms.     

Frontal Lobe Hemodynamic Responses to Painful Stimulation: A Potential Brain Marker of Nociception

The purpose of this study was to use functional near-infrared spectroscopy (fNIRS) to examine patterns of both activation and deactivation that occur in the frontal lobe in response to noxious stimuli. The frontal lobe was selected because it has been shown to be activated by noxious stimuli in functional magnetic resonance imaging studies. The brain region is located behind the forehead which is devoid of hair, providing a relative ease of placement for fNIRS probes on this area of the head. Based on functional magnetic resonance imaging studies showing blood-oxygenation-level dependent changes in the frontal lobes, we evaluated functional near-infrared spectroscopy measures in response to two levels of electrical pain in awake, healthy human subjects (n = 10; male = 10). Each subject underwent two recording sessions separated by a 30-minute resting period. Data collected from 7 subjects were analyzed, containing a total of 38/36 low/high intensity pain stimuli for the first recording session and 27/31 pain stimuli for the second session. Our results show that there is a robust and significant deactivation in sections of the frontal cortices. Further development and definition of the specificity and sensitivity of the approach may provide an objective measure of nociceptive activity in the brain that can be easily applied in the surgical setting.