The mangrove forest as a feeding ground and nursery habitat for the ichthyofauna: Mida Creek in Kenya

peer reviewedMangrove forests are among the most productive ecosystems, sustaining both terrestrial and aquatic fauna (Kathiresan, 2011). They are important to coastal fisheries by providing foraging and hiding places for commercially valuable fishes (Tomlinson, 1986; Rönnbäck 1999). This research investigated the fish assemblage of Mida Creek (Kenya, East Africa) as well as the presumed feeding and nursery functions of the area for the ichthyofauna present. This explorative study contributes to a Kenyan-Flemish project in which scientists aim to identify the impacts of human exploitation and management regimes of mangroves on biodiversity richness and abundance, including demersal fish. The species composition of the ichthyofauna of Mida and trophic interactions therein was studied for five representative sampling areas. These sites are located at various distances from local villages in order to include the effect of different degrees of human disturbance. Samples were collected during 5-6 consecutive days close to spring tide in mid July 2011. Fishes were caught using several types of passive fishing gears such as large and small fyke nets, gill nets and occasionally beach seine. Each individual was identified to species level, measured and weighed. We performed stomach content analysis to provide information about fish diet. Furthermore, stable isotope analysis was applied on most fishes in order to detect whether the source of primary production for the higher trophic levels is mangrove-related or not. A total of 29 fish species was found with a catch of 939 teleost specimens. Our analyses showed that a majority of fish belonged to the zoobenthivorous/omnivorous trophic mode, they were mainly feeding on invertebrates. Their diet was quite similar over different locations and life stages. Two species (Sphyraena barracuda and Synodus variegatus) exhibited a mixed diet with a piscivorous preference. Results concerning the population structure suggested that the fish community of Mida consisted of both transient and resident species. Juveniles were, however, numerically more abundant in the whole area than adult specimens. Based on our restricted sampling period and methodology, we were not able to accurately detect human impacts on fish stock and species composition between locations. Finally, our results confirm that Mida Creek mangrove is an important habitat for the ichthyofauna especially for juvenile fishes. Its role as feeding and nursery ground appears well established

Growth rings, growth ring formation and age determination in the mangrove <i>Rhizophora mucronata</i>

Background and Aims The mangrove Rhizophora mucronata has previously been reported to lack annual growth rings, thus barring it from dendrochronological studies. In this study the reported absence of the growth rings was reconsidered and the periodic nature of light and dark brown layers visible on polished stem discs investigated. In addition, the formation of these layers in relation to prevailing environmental conditions, as well as their potential for age determination of the trees, was studied.Methods Trees of known age were collected and a 2.5-year cambial marking experiment was conducted to determine the periodic nature of the visible growth layers.Key Results Annual indistinct growth rings were detected in R. mucronata and are defined by a low vessel density earlywood and a high vessel density latewood. The formation of these growth rings and their periodic nature was independent from site-specific environmental conditions in two forests along the Kenyan coast. However, the periodic nature of the rings was seriously affected by slow growth rates, allowing accurate age determination only in trees with radial growth rates above 0.5 mm year(-1). The onset of the formation of the low vessel density wood coincided with the onset of the long rainy season (April-May) and continues until the end of the short rainy season (November). The high vessel density wood is formed during the dry season (December-March). Age determination of the largest trees collected in the two studied forests revealed the relatively young age of these trees (+/-100 years).Conclusions This study reports, for the first time, the presence of annual growth rings in the mangrove R. mucronata, which offers further potential for dendrochronological and silvicultural applications

Bordetella avium cross-reacts with B. bronchiseptica by ELISA but natural B. avium infection in rats is unlikely

The specificity of a Bordetella bronchiseptica antibody ELISA for the monitoring of laboratory rodents  was re-evaluated by studying the serological relationship of the B. bronchiseptica antigen and antigens of  B. avium, B. hinzii, B. holmesii and an unclassified Bordetella sp. Immunization of rats with B. avium  strains induced antibodies to the B. bronchiseptica antigen. Bordetella antibody free rats that were experimentally  infected with a B. avium strain seroconverted to the bacterium but not to B. bronchiseptica and  were B. avium culture positive at one week postinfection but not at 6 weeks. Pathogen free rats exposed to  the B. avium infected rats remained free from any cultural or serological evidence of B. avium infection.  Lung lesions were not seen in experimentally infected and exposed rats. Natural B. avium infection in rats  therefore seems unlikely.

Shelter from the storm? Use and misuse of coastal vegetation bioshields for managing natural disasters

Vegetated coastal ecosystems are known to provide myriad ecosystem services to billions of people globally. However, in the aftermath of a series of recent natural disasters, including the Indian Ocean Tsunami, Hurricane Katrina and Cyclone Nargis, coastal vegetation has been singularly promoted as a protection measure against large storm surges and tsunami. In this paper, we review the use of coastal vegetation as a "bioshield" against these extreme events. Our objective is to investigate the long-term consequences of rapid plantation of bioshields on local biodiversity and human capital. We begin with an overview of the scientific literature, in particular focusing on studies published since the Indian Ocean Tsunami in 2004 and discuss the science of wave attenuation by vegetation. We then explore case studies from the Indian subcontinent and evaluate the detrimental impacts bioshield plantations can have upon native ecosystems. We draw a clear distinction between coastal restoration and the introduction of exotic species in inappropriate locations in the name of coastal protection. We conclude by placing existing bioshield policies into a larger socio-political context and outline a new direction for coastal vegetation policy and research

Gender specific effects of the calcium channel TRPV4 on osteoporotic fracture risk and osteoblast-osteoclast coupling

TRPV4 is a member of the transient receptor potential (TRP) superfamily and responds to an array of stimuli, including osmolarity, pH and pressure. Recent findings showing that TRPV4 deficiency leads to reduced sensing of mechanical stimuli led us to explore the role of TRPV4 in bone. TRPV4 mRNA was abundantly expressed in both osteoblasts and osteoclasts as assessed by qPCR. Femoral cortical and trabecular bone mass as assessed by microcomputed tomography was higher in male TRPV4 knockout mice compared to wild type mice. Despite thicker bone structures, cortical porosity was increased in the male TRPV4 knockout mice leading to reduced bone strength as assessed by 3-point bending. Osteoclast and osteoblast differentiation and function was studied, using bone marrow cultures from wildtype and TRPV4 knockout mice. Osteoclast numbers as well as the formation of resorption pits were significantly reduced in cultures of TRPV4 knockout mice compared to wildtype littermates. In contrast, osteoblast differentiation and matrix mineralization was significantly increased in TRPV4 knockout bone marrow cultures. None of these parameters were significantly different in bones and bone marrow cultures of female knock out mice. These data implicate a gender-specific osteoblast–osteoclast uncoupling and support the observed increase in bone mass in male TRPV4 deficient mice. To assess the possible impact of TRPV4 on osteoporotic outcome in humans, we extracted data from the genome-wide association study within the Rotterdam Study. Two single nucleotide polymorphisms (SNPs) in the TRPV4 gene showed strong associations with osteoporotic fracture risk fragility fracture risk and hip fracture risk in men, but not in women. This was not affected after adjusting for height, weight, age and bone mineral density (BMD). In conclusion, TRPV4 plays an important role in male but not female bone biology. Apparently, the increased periosteal bone apposition fails to overcome the increased cortical porosity, leading to reduced bone strength in TRPV4 deficient male mice. In line with the gender-specific findings in mice, variations in the TRPV4 gene are predicting fracture risk in men but not in women

Investigating the role of ASCC1 in the causation of bone fragility

Bi-allelic variants in ASCC1 cause the ultrarare bone fragility disorder “spinal muscular atrophy with congenital bone fractures-2” (SMABF2). However, the mechanism by which ASCC1 dysfunction leads to this musculoskeletal condition and the nature of the associated bone defect are poorly understood. By exome sequencing, we identified a novel homozygous deletion in ASCC1 in a female infant. She was born with severe muscular hypotonia, inability to breathe and swallow, and virtual absence of spontaneous movements; showed progressive brain atrophy, gracile long bones, very slender ribs, and a femur fracture; and died from respiratory failure aged 3 months. A transiliac bone sample taken postmortem revealed a distinct microstructural bone phenotype with low trabecular bone volume, low bone remodeling, disordered collagen organization, and an abnormally high bone marrow adiposity. Proteomics, RNA sequencing, and qPCR in patient-derived skin fibroblasts confirmed that ASCC1 was hardly expressed on protein and RNA levels compared with healthy controls. Furthermore, we demonstrate that mutated ASCC1 is associated with a downregulation of RUNX2, the master regulator of osteoblastogenesis, and SERPINF1, which is involved in osteoblast and adipocyte differentiation. It also exerts an inhibitory effect on TGF-β/SMAD signaling, which is important for bone development. Additionally, knockdown of ASCC1 in human mesenchymal stromal cells (hMSCs) suppressed their differentiation capacity into osteoblasts while increasing their differentiation into adipocytes. This resulted in reduced mineralization and elevated formation of lipid droplets. These findings shed light onto the pathophysiologic mechanisms underlying SMABF2 and assign a new biological role to ASCC1 acting as an important pro-osteoblastogenic and anti-adipogenic regulator.</p

Role of radiography, MRI and FDG-PET/CT in diagnosing, staging and therapeutical evaluation of patients with multiple myeloma

Multiple myeloma is a malignant B-cell neoplasm that involves the skeleton in approximately 80% of the patients. With an average age of 60 years and a 5-years survival of nearly 45% Brenner et al. (Blood 111:2516–2520, 35) the onset is to be classified as occurring still early in life while the disease can be very aggressive and debilitating. In the last decades, several new imaging techniques were introduced. The aim of this review is to compare the different techniques such as radiographic survey, multidetector computed tomography (MDCT), whole-body magnetic resonance imaging (WB-MRI), fluorodeoxyglucose positron emission tomography- (FDG-PET) with or without computed tomography (CT), and 99mTc-methoxyisobutylisonitrile (99mTc-MIBI) scintigraphy. We conclude that both FDG-PET in combination with low-dose CT and whole-body MRI are more sensitive than skeleton X-ray in screening and diagnosing multiple myeloma. WB-MRI allows assessment of bone marrow involvement but cannot detect bone destruction, which might result in overstaging. Moreover, WB-MRI is less suitable in assessing response to therapy than FDG-PET. The combination of PET with low-dose CT can replace the golden standard, conventional skeletal survey. In the clinical practise, this will result in upstaging, due to the higher sensitivity