Coral settlement onto Halimeda opuntia: a fatal attraction to an ephemeral substrate?

Degraded reefs with a high abundance of macroalgae usually also have low densities of coral recruits. Few studies, however, have examined whether these algae affect coral larval settlement. This study demonstrates, experimentally, that larvae of the Caribbean coral Favia fragrum can settle on the green alga Halimeda opuntia even when another substrate more suitable for settlement is present. Larval settlement onto experimental substrates was quantified under three treatments: rubble only, rubble plus plastic algal mimic, and rubble plus live H. opuntia. Similar total larval settlement was observed in all treatments. No larvae settled on the algal mimic, but total settlement was similar on the rubble in the first two treatments, showing that the rubble alone offered sufficient substrate for high settlement success. About half the larvae in the live algal treatment settled on H. opuntia instead of on the rubble, showing that larvae did not reject this substrate as they did the algal mimic. This result raises the possibility that corals will settle on some macroalgae when their abundance is high. Most macroalgae, including H. opuntia, are ephemeral substrates unsuitable for post-settlement survival. Such unexpected settlement may therefore have significant consequences for coral recruitment success on algal-dominated reefs.     

The application of spectroscopy techniques for diagnosis of malaria parasites and arboviruses and surveillance of mosquito vectors: A systematic review and critical appraisal of evidence

Spectroscopy-based techniques are emerging diagnostic and surveillance tools for mosquito-borne diseases. This review has consolidated and summarised recent research in the application of Raman and infrared spectroscopy techniques including near- and mid-infrared spectroscopy for malaria and arboviruses, identified knowledge gaps, and recommended future research directions. Full-length peer-reviewed journal articles related to the application of Raman and infrared (near- and mid-infrared) spectroscopy for malaria and arboviruses were systematically searched in PUBMED, MEDILINE, and Web of Science databases using the PRISMA guidelines. In text review of identified studies included the methodology of spectroscopy technique used, data analysis applied, wavelengths used, and key findings for diagnosis of malaria and arboviruses and surveillance of mosquito vectors. A total of 58 studies met the inclusion criteria for our systematic literature search. Although there was an increased application of Raman and infrared spectroscopy-based techniques in the last 10 years, our review indicates that Raman spectroscopy (RS) technique has been applied exclusively for the diagnosis of malaria and arboviruses. The mid-infrared spectroscopy (MIRS) technique has been assessed for the diagnosis of malaria parasites in human blood and as a surveillance tool for malaria vectors, whereas the near-infrared spectroscopy (NIRS) technique has almost exclusively been applied as a surveillance tool for malaria and arbovirus vectors.Conclusions/SignificanceThe potential of RS as a surveillance tool for malaria and arbovirus vectors and MIRS for the diagnosis and surveillance of arboviruses is yet to be assessed. NIRS capacity as a surveillance tool for malaria and arbovirus vectors should be validated under field conditions, and its potential as a diagnostic tool for malaria and arboviruses needs to be evaluated. It is recommended that all 3 techniques evaluated simultaneously using multiple machine learning techniques in multiple epidemiological settings to determine the most accurate technique for each application. Prior to their field application, a standardised protocol for spectra collection and data analysis should be developed. This will harmonise their application in multiple field settings allowing easy and faster integration into existing disease control platforms. Ultimately, development of rapid and cost-effective point-of-care diagnostic tools for malaria and arboviruses based on spectroscopy techniques may help combat current and future outbreaks of these infectious diseases.     

Potent inhibition of sperm motility by palytoxin

Palytoxin, produced by a stationary marine animal and one of the most toxic substances known, was used as a spear poison in ancient Hawaii to cause death by cardiovascular contracture. We report here that the motility of hamster caudal epididymal (HCE) and other sperm can be inhibited by as little as 10⁻¹³ M palytoxin in a time-dependent manner. This inhibition manifested itself as a loss in flagellar amplitude, often accompanied by an increase in beat frequency, resulting in a loss of forward progression and ultimately cessation of movement. Similar effects were observed in sperm from guinea pigs, rabbit, cattle, sea urchins and man. Preincubation with palytoxin did not prevent the induction of motility from quiescence in HCE sperm when free calcium ion was added. However, regardless of the timing of palytoxin addition this very vigorous motility disappeared shortly after it appeared. These, plus earlier observations showing palytoxin did not cause lysis under similar conditions or inhibit the progressive motility of demembranated sperm axoneme preparations, suggest both that this large molecule acts via the plasma membrane to cause its exceedingly toxic effects and that spermatozoa may be useful for the investigation of the mechanism of action of palytoxin.     

Examining the Use of Mass Transplantation of Brooding and Spawning Corals to Support Natural Coral Recruitment in Sulawesi/Indonesia

Coral transplantation is frequently advocated as a possible means of coral reef rehabilitation. One of the purported benefits of transplantation is a positive effect of transplants on coral recruitment by sexual reproduction of transplants (“seeding”) and/or settlement cues generated by the presence of live coral (“attraction”). However, evidence for this assertion is scarce. Here, we investigated the effect of coral transplantation on larval recruitment. A total of 6,164 fragments of four coral species (acroporids and pocilloporids) were transplanted at three sites in North Sulawesi, Indonesia. Coral recruitment onto limestone settlement plates was examined every 3 months and on concrete structures at the end of the study (≥15 months) in the presence and absence of transplants. Transplant survival after 1 year ranged between 20 and 30% for pocilloporids and between 40 and 80% for acroporids. Transplantation had no consistent effect on the number of coral recruits on the settlement plates or on the concrete structures. Recruitment was relatively high compared to other locations in the region and fluctuated seasonally, with increased rates in all treatments during peaks of reproduction. We conclude that, in the presence of high background recruitment and detrimental environmental conditions, coral transplantation may not be an effective method to boost coral recruitment. The provision of stable substrate for settlement in the form of artificial reefs, combined with improved management to reduce chronic stressors, constitutes a better use of resources.     

Enhanced passive surveillance dengue infection among febrile children: Prevalence,co-infections and associated factors in Cameroon

Dengue virus (DENV) causes a spectrum of diseases ranging from asymptomatic, mild febrile to a life-threatening illness: dengue hemorrhagic fever. The main clinical symptom of dengue is fever, similar to that of malaria. The prevalence of dengue virus infection, alone or in association with other endemic infectious diseases in children in Cameroon is unknown. The aim of this study was to determine the prevalence of dengue, malaria and HIV in children presenting with fever and associated risk factors.Dengue overall prevalence was 20.2%, Malaria cases were 52.7% and HIV cases represented 12.6%. The prevalence of dengue-HIV co-infection was 6.0% and that of Malaria-dengue co-infection was 19.5%. Triple infection prevalence was 4.3%. Dengue virus infection is present in children and HIV-Dengue or Dengue- Malaria co-infections are common. Dengue peak prevalence was between August and October. Sex and age were not associated with dengue and dengue co-infections. However, malaria as well as HIV were significantly associated with dengue (P = 0.001 and 0.028 respectively). The diagnosis of dengue and Malaria should be carried out routinely for better management of fever.