Microstructural morphology in early dermal denticles of hammerhead sharks (Elasmobranchii: Sphyrnidae) and related taxa

Mello, W.C., de Carvalho, J.J., Brito, P.M.M. 2011. Microstructural morphology in early dermal denticles of hammerhead sharks (Elasmobranchii: Sphyrnidae) and related taxa. —Acta Zoologica (Stockholm) 00 : 1–7. This study uses scanning electron microscopies to investigate and describe the microstructural diversity of dermal denticles in the family Sphyrnidae, which comprises all living hammerhead shark species, comparing them to other related taxa (i.e. Carcharhinus dussumieri, Carcharhinus plumbeus, Carcharhinus acronotus, Rhizoprionodon acutus, Negaprion brevirostris and Hemigaleus microstoma). The results reveal that sphyrnids present noticeable microstructures in the dermal denticles, distinguishing them from the other related species investigated. Additionally, scale patterns are the same in three distinct body regions (i.e. cephalic, branchial and dorsal fin). Species of Sphyrnidae that reach bigger total lengths and that are widely distributed (i.e. Sphyrna lewini and Sphyrna mokarran) presented more, smaller and nearly hexagonal microstructures that do not cover the entire scale surface, unlike species reaching smaller sizes and restricted to coastal habits (i.e. Sphyrna tiburo, Sphyrna tudes, Sphyrna media and Eusphyra blochii). The sphyrnid scales are similar to R. acutus and C. dussumieri rather than to the other species, but it is not possible to identify the sphyrnid species only by scale features. It is clear that a similar morphology of scales is not necessarily related to similar life habits, and that they are candidates to provide new characters in phylogenetical studies among sphyrnids.     

Ancient Substructure in Early mtDNA Lineages of Southern Africa

Among the deepest-rooting clades in the human mitochondrial DNA (mtDNA) phylogeny are the haplogroups defined as L0d and L0k, which are found primarily in southern Africa. These lineages are typically present at high frequency in the so-called Khoisan populations of hunter-gatherers and herders who speak non-Bantu languages, and the early divergence of these lineages led to the hypothesis of ancient genetic substructure in Africa. Here we update the phylogeny of the basal haplogroups L0d and L0k with 500 full mtDNA genome sequences from 45 southern African Khoisan and Bantu-speaking populations. We find previously unreported subhaplogroups and greatly extend the amount of variation and time-depth of most of the known subhaplogroups. Our major finding is the definition of two ancient sublineages of L0k (L0k1b and L0k2) that are present almost exclusively in Bantu-speaking populations from Zambia; the presence of such relic haplogroups in Bantu speakers is most probably due to contact with ancestral pre-Bantu populations that harbored different lineages than those found in extant Khoisan. We suggest that although these populations went extinct after the immigration of the Bantu-speaking populations, some traces of their haplogroup composition survived through incorporation into the gene pool of the immigrants. Our findings thus provide evidence for deep genetic substructure in southern Africa prior to the Bantu expansion that is not represented in extant Khoisan populations.     

FAM111A Mutations Result in Hypoparathyroidism and Impaired Skeletal Development

Kenny-Caffey syndrome (KCS) and the similar but more severe osteocraniostenosis (OCS) are genetic conditions characterized by impaired skeletal development with small and dense bones, short stature, and primary hypoparathyroidism with hypocalcemia. We studied five individuals with KCS and five with OCS and found that all of them had heterozygous mutations in FAM111A. One mutation was identified in four unrelated individuals with KCS, and another one was identified in two unrelated individuals with OCS; all occurred de novo. Thus, OCS and KCS are allelic disorders of different severity. FAM111A codes for a 611 amino acid protein with homology to trypsin-like peptidases. Although FAM111A has been found to bind to the large T-antigen of SV40 and restrict viral replication, its native function is unknown. Molecular modeling of FAM111A shows that residues affected by KCS and OCS mutations do not map close to the active site but are clustered on a segment of the protein and are at, or close to, its outer surface, suggesting that the pathogenesis involves the interaction with as yet unidentified partner proteins rather than impaired catalysis. FAM111A appears to be crucial to a pathway that governs parathyroid hormone production, calcium homeostasis, and skeletal development and growth.     

E. coli outbreak in a neonate intensive care unit in a general hospital in Mexico City

Nosocomial infections are a major cause of morbidity and mortality among neonates admitted to neonatal intensive care units (NICUs). The aim of this paper was to describe an outbreak of Escherichia coli among infants admitted to the NICU of the General Hospital “Dr. Manuel Gea Gonzalez” in May of 2008. The isolated E. coli strains were identified using standard biochemical methods. The susceptibilities of these strains were analysed by determining their minimal inhibitory concentrations. Following this, their molecular relationships to each other were assessed by pulsed field gel electrophoresis (PFGE) analysis and corroborated by serology. Twelve E. coli strains were isolated from blood, urine, or indwelling catheter samples from five cases of preterm infants within a 3-day period. Patients were admitted to the NICU of the general hospital and, during the outbreak, developed sepsis caused by E. coli. For four of the patients, the average age was 23 days, while one patient was a 3-month-old infant. Prior to sepsis, the infants had received assisted ventilation and hyperalimentation through a central venous catheter. Two profiles were observed by PFGE; profile A was identified as the outbreak’s cause and an outcome of cross-infection, while profile B showed genetic differences but serologically it was identified as part of the same serotype. We conclude that E. coli colonised the patients through horizontal transmission. A focal source of the microorganism in this outbreak was not identified, but cross-transmission through handling was the most probable route.     

Detecting Signatures of Selection Through Haplotype Differentiation Among Hierarchically Structured Populations

The detection of molecular signatures of selection is one of the major concerns of modern population genetics. A widely used strategy in this context is to compare samples from several populations and to look for genomic regions with outstanding genetic differentiation between these populations. Genetic differentiation is generally based on allele frequency differences between populations, which are measured by F_ST or related statistics. Here we introduce a new statistic, denoted hapFLK, which focuses instead on the differences of haplotype frequencies between populations. In contrast to most existing statistics, hapFLK accounts for the hierarchical structure of the sampled populations. Using computer simulations, we show that each of these two features—the use of haplotype information and of the hierarchical structure of populations—significantly improves the detection power of selected loci and that combining them in the hapFLK statistic provides even greater power. We also show that hapFLK is robust with respect to bottlenecks and migration and improves over existing approaches in many situations. Finally, we apply hapFLK to a set of six sheep breeds from Northern Europe and identify seven regions under selection, which include already reported regions but also several new ones. We propose a method to help identifying the population(s) under selection in a detected region, which reveals that in many of these regions selection most likely occurred in more than one population. Furthermore, several of the detected regions correspond to incomplete sweeps, where the favorable haplotype is only at intermediate frequency in the population(s) under selection.     

Detection and quantification of probiotic strain Lactobacillus gasseri K7 in faecal samples by targeting bacteriocin genes

Lactobacillus gasseri K7 is a probiotic strain that produces bacteriocins gassericin K7 A and K7 B. In order to develop a real-time quantitative PCR assay for the detection of L. gasseri K7, 18 reference strains of the Lactobacillus acidophilus group and 45 faecal samples of adults who have never consumed strain K7 were tested with PCR using 14 pairs of primers specific for gassericin K7 A and K7 B gene determinants. Incomplete gassericin K7 A or K7 B gene clusters were found to be dispersed in different lactobacilli strains as well as in faecal microbiota. One pair of primers was found to be specific for the total gene cluster of gassericin K7A and one for gassericin K7B. The real-time PCR analysis of faecal samples spiked with K7 strain revealed that primers specific for the gene cluster of the gassericin K7 A were more suitable for quantitative determination than those for gassericin K7 B, due to the lower detection level. Targeting of the gassericin K7 A or K7 B gene cluster with specific primers could be used for detection and quantification of L. gasseri K7 in human faecal samples without prior cultivation. The results of this study also present new insights into the prevalence of bacteriocin-encoding genes in gastrointestinal tract.     

Effects of dopaminergic system activation on feeding behavior and growth performance of the sea bass (Dicentrarchus labrax): A self-feeding approach

Dopamine is synthesized from l-dopa and subsequently processed into norepinephrine and epinephrine. Any excess neurotransmitter can be taken up again by the neurons to be broken down enzymatically into DOPAC. The effect of dopamine on mammalian food intake is controversial. Mice unable to synthesize central dopamine die of starvation. However, studies have also shown that central injection of dopamine inhibits food intake. The effect of dopaminergic system in the fish feeding behavior has been scarcely explored. We report that the inclusion of l-dopa in the diets results in the activation of sea bass central dopaminergic system but also in the significant increase of the hypothalamic serotonin levels. Dietary l-dopa induces a decrease of food intake and feed conversion efficiency that drives a decline of all growth parameters tested. No behavioral effects were observed after l-dopa treatment. l-dopa treatment stimulated central expression of NPY and CRF. It suggests that CRF might mediate l-dopa effects on food intake but also that CRF neurons lie downstream of NPY neurons in the hierarchical forebrain system, thus controlling energy balance. Unexpectedly, dietary administration of haloperidol, a D₂-receptor antagonist, cannot block dopamine effects but also induces a decline of the food intake. This decrease seems to be a side effect of haloperidol treatment since fish exhibited a decreased locomotor activity. We conclude that oral l-dopa inhibits sea bass food intake and growth. Mechanism could also involve an increase of hypothalamic serotoninergic tone.     

Pollen analysis of honeys from the Mamora forest region (NW Morocco)

The present work refers to the pollen analysis of 35 Moroccan honey samples from the Mamora forest region. The samples were directly provided by the beekeepers, all professionals. The quantitative analysis showed that nectar is the main honey source in the samples studied, and that most honeys have a medium-low presence of botanical elements (BEN). The qualitative analysis of the samples showed the presence of 54 taxa belonging to 29 families, and 31 of the samples were unifloral: 24 of eucalyptus, 3 of orange, 2 of Loeflingia, 1 of mint and 1 of Ridolfia segetum. The eucalyptus honeys of the studied region are characterized by their high content in pollen grains (NGP; x¯=180000) and their low honeydew indicator elements content (HDE; x¯=4000); Plantago f. (present in 70% of the samples), Quercus f. and Brassicaceae (50%) and Ceratonia siliqua (30%) could be mentioned among the characteristic accompanying species of this honey type.     

Pollen biology in four Mediterranean Quercus species

Potential pollen production, viability and germination were studied in the most important species of Quercus in the mountains of Córdoba to determine the contribution of each species to the total amount of airborne pollen. The results were compared over two consecutive years with different rainfall patterns. The viability of pollen grains was determined at anther opening, and during the pollination period, in order to determine potential pollination capacity. Results indicated that there were differences in the number of pollen grains produced by stamen in the four species. Equally, there were differences in the number of flowers among the species, being Q. suber the species with higher number of catkins groups and flowers per individual tree. Total pollen production per tree can be summarized in the following proportion: 1: 3: 3: 6 (Q. coccifera, Q. ilex ssp. ballota, Q. faginea and Q. suber). Potential pollen viability was estimated using the Fluorochromatic Reaction (FCR) and a germination assay. The results have shown that Quercus potential pollen viability is high and declines slowly with time. Q. coccifera was the species with the highest percentage of germination, with Q. suber being the lowest.