Climate change-induced ecosystem disturbance: a review on sclerophyllous and semi-deciduous forests in Tunisia.

According to the sixth assessment report of the Intergovernmental Panel on Climate Change (IPCC), global climate change is now unequivocal. Tunisia, like many other countries, has been affected by climate changes, including rising temperatures, intense heatwaves, and altered precipitation regimes. Tunisia's mean annual temperatures has risen about +1.4 °C in the twentieth century, with the most rapid warming taking place since the 1970s. Drought represents a primary contributing factor to tree decline and dieback. Long-term drought can result in reduced growth and health of trees, thereby increasing their susceptibility to insect pests and pathogens. Reported increases in tree mortality point toward accelerating global forest vulnerability under hotter temperatures and longer, more intense droughts. In order to assess the effect of these climate changes on the current state of forest ecosystems in Tunisia and their evolution, an investigative study was required. Here, we review the current state of knowledge on the effects of climate change on sclerophyllous and semi-deciduous forest ecosystems in Tunisia. Natural disturbance during recent years, as well as the adaptability and resilience of some forest species to climate change, were surveyed. The Standardized Precipitation Evapotranspiration Index (SPEI) is a multi-scalar drought index based on climate data that has been used to analyse drought variability. The SPEI time scale analysis showed a negative trend over the 1955-2021 period in Tunisian forest regions. In 2021, Tunisia lost 280 km2 of tree cover to fires, which is equivalent to 26% of the total lost area between 2008 and 2021. Changing climate conditions have also affected phenological parameters, with an advance in the start of the green season (SOS) of 9.4 days, a delay at the end of the green season (EOS) of 5 days, with a consequent extended duration of the green season (LOS) by an average of 14.2 days. All of these alarming findings invite us to seek adaptation strategies for forest ecosystems. Adapting forests to climate change is therefore a challenge for scientists as well as policymakers and managers.

[Prevalence of Toxoplasma gondii infection in Tunisian sheep]. / Prévalence d'infection des ovins par Toxoplasma gondii en Tunisie.

The aim of this study is to estimate the prevalence of Toxoplasma gondii infection in 527 sheep from 4 governorates of Tunisia by Elisa (350 animals) and PCR (177 animals). The seroprevalence in sheep was estimated to be 1.8% (N = 166) in the governorate of Siliana (North Tunisia) and 19% (N = 184) in the governorate of Kasserine (Central Tunisia) with a commercial Elisa kit. T. gondii DNA was extracted from the apex of the heart in 25.5% (N = 106) of sheep from the Sidi-Bouzid governorate (Central Tunisia) and 12.7% (N = 71) from the Ben-Arous governorate (North Tunisia). There was no statistically significant difference between different age categories' prevalence within each locality. Our results indicate that T. gondii infection is frequent in Tunisian sheep. The implementation of a national control programme against toxoplasmosis should not neglect sheep as a frequently infected intermediate host.

Approaches for the identification of potential excreted/secreted proteins of Leishmania major parasites.

Leishmania parasites are able to survive in host macrophages despite the harsh phagolysosomal vacuoles conditions. This could reflect, in part, their capacity to secrete proteins that may play an essential role in the establishment of infection and serve as targets for cellular immune responses. To characterize Leishmania major proteins excreted/secreted early after promastigote entry into the host macrophage, we have generated antibodies against culture supernatants of stationary-phase promastigotes collected 6 h after incubation in conditions that partially reproduce those prevailing in the parasitophorous vacuole. The screening of an L. major cDNA library with these antibodies led us to isolate 33 different cDNA clones that we report here. Sequence analysis revealed that the corresponding proteins could be classified in 3 groups: 9 proteins have been previously described as excreted/secreted in Leishmania and/or other species; 11 correspond to known proteins already characterized in Leishmania and/or other species although it is unknown whether they are excreted/secreted and 13 code for unknown proteins. Interestingly, the latter are transcribed as shown by RT-PCR and some of them are stage regulated. The L. major excreted/secreted proteins may constitute putative virulence factors, vaccine candidates and/or new drug targets.