Changes in expression of Slit1 and its receptor Robo2 in trigeminal ganglion and inferior alveolar nerve following inferior alveolar nerve axotomy in adult rats: a pilot study.

The objective of this study was to analyze changes in expression pattern of Slit1 and Robo2, and to clarify the relationship between these changes and functional recovery of the axotomized inferior alveolar nerve (IAN) without repair using a rat IAN axotomy model. Slit1 and Robo2 were weakly expressed in samples taken from trigeminal ganglion (TG) and IAN of sham surgery rats. In axotomized rats, expression levels increased significantly from day 2 to day 28 post-axotomy, with peaks on days 14 (Slit1) and 7 (Robo2) after axotomy (relative to sham: Slit1 in TG P<0.0005, Slit1 in IAN P = 0.003, Robo2 in TG P<0.0005, and Robo2 in IAN P<0.0005). Over-expressed Slit1 and Robo2 in both the TG and IANs of axotomized rats did not return to sham levels during the 28-day observation period of this study. The regeneration and functional recovery of axotomized IAN was evaluated by jaw opening reflex (JOR) recorded before and after axotomy. JOR occurrence (0% on day 7, 35% on day 14, and 85% on day 28) increased gradually, and the relative threshold of electrical stimulation eliciting JOR decreased gradually (1000.0 ± 0.0% on day 7, 854.3 ± 132.5% on day 14, and 302.6 ± 92.3% on day 28). On day 28 after axotomy, JOR occurrence and the relative JOR threshold had almost returned to those of sham rats. These findings suggest that Slit1 and Robo2 are involved in the regeneration and functional recovery of the axotomized IAN.

Rehabilitation studies and recovery of a once lifeless estuary: the Golden Horn.

Within this study fluctuations in biodiversity of the Golden Horn from past to present are evaluated. Limited studies and observations dating back to 60 years ago pointed out the importance of the Golden Horn as a fishery. Unfortunately, in accordance with increase in unplanned settlements and industry around the Golden Horn in the 1960s, pollution stress became a demanding factor for this unique environment, affecting biodiversity adversely. Preliminary studies in the 1990s indicated survival of only a couple of pollution-resistant species, at the relatively cleaner outer estuary. Following intensification of "still ongoing" rehabilitation studies in 1998, a remarkable day-by-day recovery in marine life has began, in regard to improvements in water quality. Surveys conducted in 2002 using SCUBA, documented the level of diversification of life at the Golden Horn. Extended till Haliç Bridge, all appropriate substratums were intensely covered by macrobenthic forms and particularly filter feeders dominated the plankton-rich ecosystem. Detection of seahorses at the inner-middle parts of the estuary, in addition to numerous fish, invertebrate and macroalgae species, clearly depicted the level of recovery and change in the ecosystem. All results support the existence of a dynamic biological life at the Golden Horn, improving considerably with rehabilitation studies. Achieving the diversity of the 1940s is not possible, since the Black and Marmara seas, highly influencing water quality in the Golden Horn are also suffering from anthropogenic impacts and are far beyond their rich diversity in the 1940s. However, it is obvious that ecosystems should recover when mankind gave a chance to them. Recovery of the recently lifeless Golden Horn in such a short period of time is a very good example.

Benthic community structure of the Bosphorus and surrounding area.

Abstract Spatial and temporal distribution of benthic communities around the Strait of Istanbul (Bosphorus) and the effect of lower layer discharge on these communities have been evaluated during studies between February-December 1999. Mytilus galloprovincialis was the dominant species with fasies at the Black Sea station that is not affected by the strait lower layer current system. On the other hand, another Black Sea station, influenced by the strait lower layer currents, has a similar biota to the strait stations. Species richness and diversity is highest in the strait than other areas. The dominant species is Maera grossimana. However, the station located at the Black Sea exit of the strait has a different biota, and various groups/species appeared to be dominant. Melinna palmata is the dominant species at the Sea of Marmara during the study period. Low dissolved oxygen values of lower layer and soft substratum of sediment resulted in wide distribution of Melinna palmata, adapted to these conditions. The closer stations to the strait in the Sea of Marmara have higher diversity as a result of hydrodynamic processes. On the other hand, coastal stations with low currents and inputs have lower index values, showing the negative effect of discharges and pollution.

Nutrient distribution in the Bosphorus and surrounding areas.

As part of a five years monitoring project "Water Quality Monitoring of the Strait of Istanbul", February-December 1999 nutrient dynamics of the Black Sea-the Sea of Marmara transect are studied to evaluate the effect of discharges given by deep disposals. Through a one-year study, upper layer nutrient concentrations were generally under the effect of northwestern-shelf Black Sea originated waters. This effect was strictly observed in July, when the upper layer flow was the thickest. On the other hand, partly in November but especially in December the northwestern-shelf Black Sea originated water flow was a minimum resulting in similar concentrations in both layers. Nutrient fluctuations also affected the chlorophyll a and POC concentrations as parameters of productivity. The nutrient concentrations decreased with the effect of spring bloom and highest chlorophyll a values were detected in November at Strait stations that did not match to the Sea of Marmara values. This fact represents the time-scale difference between the Black Sea and the Sea of Marmara. On the contrary, high nutrient concentrations in the lower layer (especially inorganic phosphate), and therefore low N:P ratios reflect the effect of deep discharge. Vertical mixing caused by meteorological conditions of the shallow station (M3) under the effect of surface discharges resulted in homogenous distribution of nutrients. Nutrient concentrations of the stations affected by deep discharge showed that the two-layer stratification of the system did not permit the discharge mix to the upper layer.