even in other specimens belonging to the order Zoantharia, which
includes P. tuberculosa, no PTX or congeners were found. No specimens
of various Zoanthus species or of Palythoa mutuki, a closely
related congener to P. tuberculosa (Reimer et al., 2007), showed
even traces of the toxins.
The results obtained in this study considerably differ from
earlier reports on PTX distribution in Caribbean coral reefs (Gleibs
and Mebs, 1999; Gleibs et al., 1995). In these studies, PTX was
found in a majority of marine organisms that are potential hosts of
the unknown PTX producer, namely zoantharians, soft corals, gorgonians,
and sponges. There are two main explanations for the
differences observed. Firstly, different methods were used for
detection of PTX and congeners. Mebs and coworkers (Gleibs et al.,
1995) relied upon haemolysis assays and HPLC separation using the
absorbance at a wavelength of 230 nm as an indicator of PTX
presence. However, in the current study, all detections were
exclusively based on LCeMS measurements, which resulted in
relatively high sensitivity and allowed for unambiguous identification
of PTX and 42-OH-PTX. Haemolytic compounds other than
PTX might have caused the haemolytic activity found in many of
the extracts from the Caribbean Sea, resulting in an overestimation
of PTX distribution. A considerable proportion of bacterial isolates
(17 out of 250, i.e. 7%) from P. caribaeorum showed PTX-like haemolytic
activity (Seemann et al., 2009), and bacterial isolates from
PTX-positive P. tuberculosa colonies from Okinawa caused ouabaindelayed
haemolysis but did not produce PTX as concluded from
LCeMS experiments (unpublished data). Secondly, one needs to be
cautious when comparing distribution patterns obtained from
geographically very distant sampling sites, which might have
considerably different environmental conditions, for instance with
regard to water temperatures, water composition, and nutrients.
Studies conducted in the Colombian Caribbean, which includes the
Santa Marta area where Mebs and coworkers performed their
research (Gleibs and Mebs, 1999; Gleibs et al., 1995), have shown
that both human and natural stressors influence the algal cover of
reefs (Rodriguez-Ramirez et al., 2010), and a recent survey in the
same region found relatively high densities of benthic dinoflagellates
including Ostreopsis ovata and other species likely to
produce toxins (Rodriguez et al., 2010). Therefore, it may be that the
Caribbean sampling area at the times of these past studies (Gleibs
and Mebs, 1999; Gleibs et al., 1995) could have resulted in a
higher spread of PTX producing organisms. Furthermore, seasonal
effects and changes over time may play an important role. For
instance, the data of PTX and 42-OH-PTX obtained in this study
showed considerable changes in both the proportion of positive
colonies and average toxin concentrations from specimens sampled
at different times. These effects are difficult to explain as long as the
producer has not been identified. The data suggest that the
ผลิตเป็น epiphytes (สีเขียวและสาหร่ายสีแดง) ชีวิตที่
อาจจะเป็นเจ้าภาพเป็น endophytes (ปะการังอ่อน, zoantharians, hydrozoans,
ฟองน้ำ) และหญ้าที่มีศักยภาพใน PTX ที่มีส่วนผสมของวัสดุ (ปลาดาว
หอย, กุ้ง, ปลิงทะเล) ตัวอย่างสาหร่ายทั้งหมด
(n ¼ 12) การทดสอบเชิงลบสำหรับ PTX และ congeners ของมัน ปะการังอ่อน
(n ¼ 6) และฟองน้ำ (n ¼ 4) ไม่ได้มีการตรวจพบปริมาณของ
สารพิษที่เกี่ยวข้องอย่างใดอย่างหนึ่ง หญ้าที่มีศักยภาพรวมทั้งปลาดาว
หอย, กุ้งและยังผ่านการทดสอบเชิงลบทั้งหมด น่าสนใจมากที่สุด
การแปล กรุณารอสักครู่..