Browsing by Subject "Biology"
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- ItemOpen AccessEvolution of the hypoxia-sensitive cells involved in amniote respiratory reflexes(2017) Hockman, Dorit; Burns, Alan J; Schlosser, Gerhard; Gates, Keith P; Jevans, Benjamin; Mongera, Alessandro; Fisher, Shannon; Unlu, Gokhan; Knapik, Ela W; Kaufman, Charles K; Mosimann, Christian; Zon, Leonard I; Lancman, Joseph J; Dong, P Duc S; Lickert, Heiko; Tucker, Abigail S; Baker, Clare V HThe evolutionary origins of the hypoxia-sensitive cells that trigger amniote respiratory reflexes – carotid body glomus cells, and ‘pulmonary neuroendocrine cells’ (PNECs) - are obscure. Homology has been proposed between glomus cells, which are neural crest-derived, and the hypoxia-sensitive ‘neuroepithelial cells’ (NECs) of fish gills, whose embryonic origin is unknown. NECs have also been likened to PNECs, which differentiate in situ within lung airway epithelia. Using genetic lineage-tracing and neural crest-deficient mutants in zebrafish, and physical fate-mapping in frog and lamprey, we find that NECs are not neural crest-derived, but endoderm-derived, like PNECs, whose endodermal origin we confirm. We discover neural crest-derived catecholaminergic cells associated with zebrafish pharyngeal arch blood vessels, and propose a new model for amniote hypoxia-sensitive cell evolution: endoderm-derived NECs were retained as PNECs, while the carotid body evolved via the aggregation of neural crest-derived catecholaminergic (chromaffin) cells already associated with blood vessels in anamniote pharyngeal arches.
- ItemOpen AccessExpression pattern and role of Foxcl during hair follicle morphogenesis(2004) Manda, Juziel K; Professor Sue H. Kidsonhe murine Foxcl, which encodes a forkhead/winged helix transcription factor, 1s expressed in many embryonic tissues including prechondrogenic and peri-ocular mesenchyme, meninges, endothelial cells and kidney. Homozygous Foxe] null mice embryos die at birth with hydrocephalus, eye defects, and multiple skeletal abnormalities identical to those of the classical mutant, congenital hydrocephalus. Although the structure and function of murine Foxe] has been analyzed in many embryonic tissues, relatively little is known about the expression and role of this gene in the skin. To determine the Foxe] expression pattern during embryonic and neonatal skin development, this study utilised mice in which the Lac-z reporter gene was placed under the control of wild-type Foxcl promoter by homologous combination (Kume et al, 1998, Cell 93, 985-996). Lac-z encodes enzymatically active ~-galactosidase, which converts the colourless chromogenic 5-bromo-4-chloro-3-indolyl-~, Dgalactoside (X-gal) into a blue product enabling visualization of the Foxe] expression pattern. Skin samples from heterozygous and homozygous mutant mouse embryos (13.5-18.5 dpc) and neonates (P0-P7) were fixed in 4% PFA, stained for ~- galactosidase activity and processed for histology. Foxe] expression was detected by the presence of the blue colour. The results show that Foxe] is specifically expressed in the epithelial cells of the hair follicles at all stages of embryonic skin development. In the developing hair follicles Foxcl promoter activity is induced at high levels in the post-mitotic precursor cells of the hair shaft, inner root sheath and sebaceous gland of the pelage hair and whisker follicles. In mature anagen hair follicles, high levels of Foxcl are persistently detected in the keratogenous zone of the hair and sebaceous gland. Within the sebaceous glands, Foxcl was strongly expressed in cells that are located at the centre of the gland. Within the Foxcl-expressing compartments, most cells do not exhibit the nuclear proliferation marker BrdU. Co-localisation of Foxe] and apoptotic marker TUNEL was detected in keratogenous zone of the hair and in cells located closer to the sebaceous gland duct. Foxe] expression switched off during telogen. These results XVI suggest that Foxe] expression is associated with the transition from a proliferative to a post-mitotic state and that Foxe] may be involved in initiation of terminal differentiation and keratinization. High levels of Foxe] are maintained in fully differentiated hair keratinocytes and sebocytes possibly as one of the earliest events that perhaps trigger programmed cell death (apoptosis). The second objective of this study was to investigate the development of hair follicles in a mutant in order to determine the role of Foxcl. Hair follicle development was analysed in skin samples of homozygous mutant mouse embryos (13.5-l 8.5 dpc) using histological, immunocytochemical and histomorphometrical methods. Different stages of hair follicle morphogenesis were defined on the basis of accepted morphological criteria (Paus et al., 1999, J. Invest. Dermatol.; 113(4): 523-32.) Histological examination showed that hair follicle development was induced normally on the back of Foxcl mutant embryos at around 13.5 (dpc), with epidermal cells forming a hair plug (stages 1 and 2). Between 14.5 dpc - 15.5 dpc, the skin formed a completely penetrant bulbar hair follicle phenotype, which had initiated development of the inner root sheath characteristic of stages 4-5 of follicular development. Similarly, histological examination of Foxe] null follicles from 15.5 dpc to around birth showed no gross morphological defects in the hair shaft compartment where Foxe] is expressed. Quantitatively, embryonic skin showed no significant differences in rate of growth and number of hair follicles between Foxe] null mutants and wild types (P>0.05). These morphological findings suggest that the initial signalling events in embryonic hair development are independent of Foxe]. In conclusion, histological examination of the mutant skin shows that pelage hair follicle formation is initiated and proceeds normally up to the formation the bulbar hair follicles (stages 5) with no recognisable effects on the total number of induced hair follicles. The results show that Foxcl signalling is not required for induction and early development of hair follicle in embryos. Foxcl signalling, however, is likely to be essential for regulating differentiation of post-natal hair and sebaceous gland. Fmiher studies to determine how Foxe] signalling regulates post-natal hair follicle differentiation will be an excellent area for future research.
- ItemOpen AccessLong-term vegetation change in the Succulent Karoo, South Africa following 67 years of rest from grazing(2005) Rahlao, Sebataolo; Hoffman, TimmChanges in species richness and vegetation composition in the diverse semi arid Succulent Karoo vegetation of South Africa were investigated after 67 • (1937-2004) years of rest from grazing at the Worcester Veld Reserve. Vegetation change in 70 plots at this 75 ha site was assessed using multi variate ordination techniques. Changes in plant communities on termitaria sites were consistently greater than for adjacent off-termitaria sites and the north-facing slopes changed more than the south-facing slopes. There was a higher increase in diversity on off-termitaria than termitaria sites. On termitaria sites there was a general decrease in stem succulents, particularly Euphorbia mauretanica and an increase in long-lived evegreen shrubs such as Pteronia incana and Asparagus suaveo/ens. Most sites changed in a similar direction primarily determined by their association with termitaria and secondarily with .. aspect. These findings suggest a predictable and directional replacement sequence under changing disturbance (grazing) regimes in a semi-arid region.
- ItemOpen AccessA pandemic recap: lessons we have learned(2021-09-10) Coccolini, Federico; Cicuttin, Enrico; Cremonini, Camilla; Tartaglia, Dario; Viaggi, Bruno; Kuriyama, Akira; Picetti, Edoardo; Ball, Chad; Abu-Zidan, Fikri; Ceresoli, Marco; Turri, Bruno; Jain, Sumita; Palombo, Carlo; Guirao, Xavier; Rodrigues, Gabriel; Gachabayov, Mahir; Machado, Fernando; Eftychios, Lostoridis; Kanj, Souha S; Di Carlo, Isidoro; Di Saverio, Salomone; Khokha, Vladimir; Kirkpatrick, Andrew; Massalou, Damien; Forfori, Francesco; Corradi, Francesco; Delibegovic, Samir; Machain Vega, Gustavo M.; Fantoni, Massimo; Demetriades, Demetrios; Kapoor, Garima; Kluger, Yoram; Ansari, Shamshul; Maier, Ron; Leppaniemi, Ari; Hardcastle, Timothy; Vereczkei, Andras; Karamagioli, Evika; Pikoulis, Emmanouil; Pistello, Mauro; Sakakushev, Boris E.; Navsaria, Pradeep H.; Galeiras, Rita; Yahya, Ali I; Osipov, Aleksei V; Dimitrov, Evgeni; Doklestić, Krstina; Pisano, Michele; Malacarne, Paolo; Carcoforo, Paolo; Sibilla, Maria G.; Kryvoruchko, Igor A; Bonavina, Luigi; Kim, Jae I; Shelat, Vishal G; Czepiel, Jacek; Maseda, Emilio; Marwah, Sanjay; Chirica, Mircea; Biancofiore, Giandomenico; Podda, Mauro; Cobianchi, Lorenzo; Ansaloni, Luca; Fugazzola, Paola; Seretis, Charalampos; Gomez, Carlos A.; Tumietto, Fabio; Malbrain, Manu; Reichert, Martin; Augustin, Goran; Amato, Bruno; Puzziello, Alessandro; Hecker, Andreas; Gemignani, Angelo; Isik, Arda; Cucchetti, Alessandro; Nacoti, Mirco; Kopelman, Doron; Mesina, Cristian; Ghannam, Wagih; Ben-Ishay, Offir; Dhingra, Sameer; Coimbra, Raul; Moore, Ernest E; Cui, Yunfeng; Quiodettis, Martha A.; Bala, Miklosh; Testini, Mario; Diaz, Jose; Girardis, Massimo; Biffl, Walter L; Hecker, Matthias; Sall, Ibrahima; Boggi, Ugo; Materazzi, Gabriele; Ghiadoni, Lorenzo; Matsumoto, Junichi; Zuidema, Wietse P; Ivatury, Rao; Enani, Mushira A; Litvin, Andrey; Al-Hasan, Majdi N.; Demetrashvili, Zaza; Baraket, Oussama; Ordoñez, Carlos A; Negoi, Ionut; Kiguba, Ronald; Memish, Ziad A; Elmangory, Mutasim M; Tolonen, Matti; Das, Korey; Ribeiro, Julival; O’Connor, Donal B; Tan, Boun K; Van Goor, Harry; Baral, Suman; De Simone, Belinda; Corbella, Davide; Brambillasca, Pietro; Scaglione, Michelangelo; Basolo, Fulvio; De’Angelis, Nicola; Bendinelli, Cino; Weber, Dieter; Pagani, Leonardo; Monti, Cinzia; Baiocchi, Gianluca; Chiarugi, Massimo; Catena, Fausto; Sartelli, MassimoOn January 2020, the WHO Director General declared that the outbreak constitutes a Public Health Emergency of International Concern. The world has faced a worldwide spread crisis and is still dealing with it. The present paper represents a white paper concerning the tough lessons we have learned from the COVID-19 pandemic. Thus, an international and heterogenous multidisciplinary panel of very differentiated people would like to share global experiences and lessons with all interested and especially those responsible for future healthcare decision making. With the present paper, international and heterogenous multidisciplinary panel of very differentiated people would like to share global experiences and lessons with all interested and especially those responsible for future healthcare decision making.
- ItemOpen AccessSneaky African fig wasps that oviposit through holes drilled by other species(2009) Compton, Stephen G; Van Noort, Simon; McLeish, Michael; Deeble, Mark; Stone, VictoriaWatshamiella Wiebes species (Hymenoptera: Chalcidoidea: Pteromalidae: Sycoryctinae) were observed to engage, monitor and subsequently use oviposition holes made by other parasitoid fig wasp genera (Apocrypta Coquerel and Sycoryctes Mayr) to oviposit into host figs (Moraceae, Ficus) through the fig wall. They may be inquilines, klepto-parasitoids, or hyper-parasitoids; however, further biological investigations of larval diet are required to establish their life history strategy. Watshamiella species are morphologically robust, with enlarged fore femora and tibia, and aggressively interact with other fig wasps and ants. Our observations contribute towards unravelling the complex suite of behavioural adaptations and interactions involved in the community ecology of the obligate mutualism that exists between fig wasps and their host figs.
- ItemOpen AccessThe effect of clothing on decomposition and scavenging in two forensically significant habitats in Cape Town, South Africa(2024) Adams, Kara Sierra; Gibbon, VictoriaIn South Africa, identifying unknown human remains presents an ongoing challenge given the high murder rate in the country. A crucial aspect of the forensic death investigation involves estimating the postmortem interval, which is influenced by biogeographic factors specific to the region. To ensure the collection of forensically relevant data, the experimental design incorporated single, clothed individuals, as they constitute the majority of unidentified human remains in the Western Cape province. The effect of clothing on scavenging and decomposition were examined in two forensically significant habitats in Cape Town, South Africa. To explore the impact of clothing on scavenging and decomposition, research was conducted in two open habitats, one periurban habitat and one suburban habitat. Six clothed and uncaged porcine carcasses weighing 60kg each were deployed between July 2021 and January 2023 (FHS SEC REF 018_023 & 022_001). Data were collected on carcass mass loss over time, vertebrate scavenger activity, prevailing weather, and carcass tissue desiccation. A comparative sample of 16 unclothed carcasses deployed between 2014 and 2016 was analysed to assess the impact of clothing and biomass load on the decomposition rate. Overall, winter-season clothing delayed decomposition, but summer-season clothing accelerated the process. Carcass weight loss was directly affected by the scavenging of the Cape grey mongoose (Galerella pulverulenta), which accelerated the decomposition rate. Additionally, single carcasses within the same habitat decomposed quicker than the multi-carcass deployments. Natural precocious mummification is a unique phenomenon documented in the Western Cape province, and a novel component of this research was that it formed the first quantitative assessment of desiccation leading to precocious mummification. Printed computing boards inserted into the carcass tissue recorded full-thickness tissue moisture content from three sites on each carcass in 15-minute intervals. The data were analysed through generalised additive modelling with environmental temperature, humidity, solar radiation, and precipitation as covariates. Desiccation in summer appeared to follow an exponential decline, and temperature was the most influential environmental factor. These novel data demonstrate the potential of utilising accumulated degree days and moisture content to estimate the postmortem interval. The combined results advocate using single-clothed carcasses deployed across multiple seasonal trials in forensically significant locations to produce data that can be considered forensically realistic.