| 1. |
- Cardini, Ulisse, et al.
(författare)
-
Functional significance of dinitrogen fixation in sustaining coral productivity under oligotrophic conditions
- 2015
-
Ingår i: Proceedings of the Royal Society of London. Biological Sciences. - : The Royal Society. - 0962-8452 .- 1471-2954. ; 282:1818
-
Tidskriftsartikel (refereegranskat)abstract
- Functional traits define species by their ecological role in the ecosystem. Animals themselves are host-microbe ecosystems (holobionts), and the application of ecophysiological approaches can help to understand their functioning. In hard coral holobionts, communities of dinitrogen (N-2)-fixing prokaryotes (diazotrophs) may contribute a functional trait by providing bioavailable nitrogen (N) that could sustain coral productivity under oligotrophic conditions. This study quantified N-2 fixation by diazotrophs associated with four genera of hermatypic corals on a northern Red Sea fringing reef exposed to high seasonality. We found N-2 fixation activity to be 5- to 10-fold higher in summer, when inorganic nutrient concentrations were lowest and water temperature and light availability highest. Concurrently, coral gross primary productivity remained stable despite lower Symbiodinium densities and tissue chlorophyll a contents. In contrast, chlorophyll a content per Symbiodinium cell increased from spring to summer, suggesting that algal cells overcame limitation of N, an essential element for chlorophyll synthesis. In fact, N-2 fixation was positively correlated with coral productivity in summer, when its contribution was estimated to meet 11% of the Symbiodinium N requirements. These results provide evidence of an important functional role of diazotrophs in sustaining coral productivity when alternative external N sources are scarce.
|
|
| 2. |
- Cardini, Ulisse, et al.
(författare)
-
Microbial dinitrogen fixation in coral holobionts exposed to thermal stress and bleaching
- 2016
-
Ingår i: Environmental Microbiology. - : Wiley. - 1462-2912 .- 1462-2920. ; 18:8, s. 2620-2633
-
Tidskriftsartikel (refereegranskat)abstract
- Coral holobionts (i.e., coral-algal-prokaryote symbioses) exhibit dissimilar thermal sensitivities that may determine which coral species will adapt to global warming. Nonetheless, studies simultaneously investigating the effects of warming on all holobiont members are lacking. Here we show that exposure to increased temperature affects key physiological traits of all members (herein: animal host, zooxanthellae and diazotrophs) of both Stylophora pistillata and Acropora hemprichii during and after thermal stress. S. pistillata experienced severe loss of zooxanthellae (i.e., bleaching) with no net photosynthesis at the end of the experiment. Conversely, A. hemprichii was more resilient to thermal stress. Exposure to increased temperature (+ 6 degrees C) resulted in a drastic increase in daylight dinitrogen (N-2) fixation, particularly in A. hemprichii (threefold compared with controls). After the temperature was reduced again to in situ levels, diazotrophs exhibited a reversed diel pattern of activity, with increased N-2 fixation rates recorded only in the dark, particularly in bleached S. pistillata (twofold compared to controls). Concurrently, both animal hosts, but particularly bleached S. pistillata, reduced both organic matter release and heterotrophic feeding on picoplankton. Our findings indicate that physiological plasticity by coral-associated diazotrophs may play an important role in determining the response of coral holobionts to ocean warming.
|
|
| 3. |
- Rehman, I. -U, et al.
(författare)
-
Port site tuberculosis a rare post operation entity : A case report
- 2022
-
Ingår i: Annals of Medicine and Surgery. - : Ovid Technologies (Wolters Kluwer Health). - 2049-0801. ; 78
-
Tidskriftsartikel (refereegranskat)abstract
- Laparoscopic cholecystectomy is one of the most common procedures done worldwide. Post-surgical site infections are common, yet there are occurrences of uncommon complications, including port site tuberculosis (TB). We report a case of a 62-year-old man who was the victim of post-surgical site infection of port sites caused probably by improper sterilization. The patient lacked any common symptoms of tuberculosis and his initial lab investigations were not affirmative. A biopsy depicting the growth of multiple epithelioid granulomas finally led to the diagnosis of port site tuberculosis. The patient was treated by incision and drainage followed by anti-tubercular therapy. This treatment regime showed complete resolution of disease on follow-ups. Such cases require multidisciplinary team (Surgery, Pathology and Infectious disease department in our case) inputs for prompt diagnosis and treatment.
|
|
