title: VapC Toxins from Mycobacterium tuberculosis are ribonucleases that differentially inhibit growth and are neutralized by cognate VapB antitoxins

authors: Ahidjo, Bintou Ahmadou

subjects: Mycobacterium tuberculosis

abstract: The chromosome of Mycobacterium tuberculosis (Mtb) encodes forty seven toxin-antitoxin modules belonging to the VapBC family. The role of these modules in the physiology of Mtb and the function(s) served by their expansion are unknown. We investigated ten vapBC modules from Mtb and the single vapBC from M. smegmatis. Of the Mtb vapCs assessed, only Rv0549c, Rv0595c, Rv2549c and Rv2829c were toxic when expressed from a tetracycline-regulated promoter in M. smegmatis. The same genes displayed toxicity when conditionally expressed in Mtb. Toxicity of Rv2549c in M. smegmatis correlated with the level of protein expressed, suggesting that the VapC level must exceed a threshold for toxicity to be observed. In addition, the level of Rv2456 protein induced in M. smegmatis was markedly lower than Rv2549c, which may account for the lack of toxicity of this and other VapCs scored as ‘non-toxic’. The growth inhibitory effects of toxic VapCs were neutralized by expression of the cognate VapB as part of a vapBC operon or from a different chromosomal locus, while that of non-cognate antitoxins did not. These results demonstrated a specificity of interaction between VapCs and their cognate VapBs, a finding corroborated by yeast two-hybrid analyses. Deletion of selected vapC or vapBC genes did not affect mycobacterial growth in vitro, but rendered the organisms more susceptible to growth inhibition following toxic VapC expression. However, toxicity of ‘non-toxic’ VapCs was not unveiled in deletion mutant strains, even when the mutation eliminated the corresponding cognate VapB, presumably due to insufficient levels of VapC protein. Together with the ribonuclease (RNase) activity demonstrated for Rv0065 and Rv0617 – VapC proteins with similarity to Rv0549c and Rv3320c, respectively – these results suggest that the VapBC family potentially provides an abundant source of RNase activity in Mtb, which may profoundly impact the physiology of the organism.

text: VapC Toxins from Mycobacterium tuberculosis are ribonucleases that differentially inhibit growth and are neutralized by cognate VapB antitoxins The chromosome of Mycobacterium tuberculosis (Mtb) encodes forty seven toxin-antitoxin modules belonging to the VapBC family. The role of these modules in the physiology of Mtb and the function(s) served by their expansion are unknown. We investigated ten vapBC modules from Mtb and the single vapBC from M. smegmatis. Of the Mtb vapCs assessed, only Rv0549c, Rv0595c, Rv2549c and Rv2829c were toxic when expressed from a tetracycline-regulated promoter in M. smegmatis. The same genes displayed toxicity when conditionally expressed in Mtb. Toxicity of Rv2549c in M. smegmatis correlated with the level of protein expressed, suggesting that the VapC level must exceed a threshold for toxicity to be observed. In addition, the level of Rv2456 protein induced in M. smegmatis was markedly lower than Rv2549c, which may account for the lack of toxicity of this and other VapCs scored as ‘non-toxic’. The growth inhibitory effects of toxic VapCs were neutralized by expression of the cognate VapB as part of a vapBC operon or from a different chromosomal locus, while that of non-cognate antitoxins did not. These results demonstrated a specificity of interaction between VapCs and their cognate VapBs, a finding corroborated by yeast two-hybrid analyses. Deletion of selected vapC or vapBC genes did not affect mycobacterial growth in vitro, but rendered the organisms more susceptible to growth inhibition following toxic VapC expression. However, toxicity of ‘non-toxic’ VapCs was not unveiled in deletion mutant strains, even when the mutation eliminated the corresponding cognate VapB, presumably due to insufficient levels of VapC protein. Together with the ribonuclease (RNase) activity demonstrated for Rv0065 and Rv0617 – VapC proteins with similarity to Rv0549c and Rv3320c, respectively – these results suggest that the VapBC family potentially provides an abundant source of RNase activity in Mtb, which may profoundly impact the physiology of the organism.

year: 2011

title: Ecological and physical characteristics of the Te Awa O Katapaki Stream, Flagstaff, Waikato

authors: Hicks, Brendan J.

subjects: Te Awa O Katapaki Stream

abstract: 1. The fish, macroinvertebrates, aquatic vegetation, and water quality indicate that the Te Awa O Katapaki Stream is an unpolluted, pastureland stream that is typical of the Waikato region.
2. The stream has very high nutrient concentrations that probably result from the dairy farming upstream.
3. The fish fauna is dominated by the native shortfinned eels. The presence of the migratory common smelt indicates that swimming fish species also have free access to the stream from the Waikato River.
4. Fish of high conservation value, such as giant or banded kokopu (Galaxias argenteus or G. fasciatus) were absent, which is predictable given the warm, unshaded nature of the stream.
5. Fish and invertebrates would soon recolonise the restored stream following any work in the streambed.

text: Ecological and physical characteristics of the Te Awa O Katapaki Stream, Flagstaff, Waikato 1. The fish, macroinvertebrates, aquatic vegetation, and water quality indicate that the Te Awa O Katapaki Stream is an unpolluted, pastureland stream that is typical of the Waikato region.
2. The stream has very high nutrient concentrations that probably result from the dairy farming upstream.
3. The fish fauna is dominated by the native shortfinned eels. The presence of the migratory common smelt indicates that swimming fish species also have free access to the stream from the Waikato River.
4. Fish of high conservation value, such as giant or banded kokopu (Galaxias argenteus or G. fasciatus) were absent, which is predictable given the warm, unshaded nature of the stream.
5. Fish and invertebrates would soon recolonise the restored stream following any work in the streambed.

year: 2001

title: "He taketake, he hurumanu te moana i rōhia ai": Mā te Māori ngā toronga o te motu ki whenua kē e taurima?

authors: Dewes, Kaneihana

subjects: Iwi taketake

abstract: Kai te tino ia o te tuhinga rangahau nei, he whakatōmene i te āhua kaiārahi o te Māori i ngā tūāhua hono ki ahurea kē. Mā konei e whakatau ai, e whakatūwherahia rānei ngā āhuatanga e mea ana mā te Māori ngā toronga o te motu ki whenua kē e taurima. He momo tēnei nā te Māori, i takea mai i ngā mahi pokai moana, me ngā waka i whakaterea i ngā rohenga moana o Te Moana-nui-a-Kiwa, ā, puta noa. Waihoki, he taonga tonu wā tātau kai ngā tauira o ngā tūhononga ahurea o ngā iwi taketake o te ao; he taonga anō kai waenganui i a tātau ngā whenua maha i pakanga ki rāwāhi, he tohu nui nā te ‘price of citizenship’. He momo nā te Māori te tātaki i ngā mahi whakarauora reo, waihoki, he rite tonu te noho tahi ki whenua kē i roto i te kōingo ki te whakatipu i te reo o te whenua. Mā konei, ka marohi ai te hiranga o Te Reo Māori me ngā Tikanga Māori, tēnei hiranga e tohu ana i te hua o ngā hononga ahurea ki ngā iwi taketake huri noa, kia whai hua mō Niu Tireni i ngā toronga ki whenua kē.

text: "He taketake, he hurumanu te moana i rōhia ai": Mā te Māori ngā toronga o te motu ki whenua kē e taurima? Kai te tino ia o te tuhinga rangahau nei, he whakatōmene i te āhua kaiārahi o te Māori i ngā tūāhua hono ki ahurea kē. Mā konei e whakatau ai, e whakatūwherahia rānei ngā āhuatanga e mea ana mā te Māori ngā toronga o te motu ki whenua kē e taurima. He momo tēnei nā te Māori, i takea mai i ngā mahi pokai moana, me ngā waka i whakaterea i ngā rohenga moana o Te Moana-nui-a-Kiwa, ā, puta noa. Waihoki, he taonga tonu wā tātau kai ngā tauira o ngā tūhononga ahurea o ngā iwi taketake o te ao; he taonga anō kai waenganui i a tātau ngā whenua maha i pakanga ki rāwāhi, he tohu nui nā te ‘price of citizenship’. He momo nā te Māori te tātaki i ngā mahi whakarauora reo, waihoki, he rite tonu te noho tahi ki whenua kē i roto i te kōingo ki te whakatipu i te reo o te whenua. Mā konei, ka marohi ai te hiranga o Te Reo Māori me ngā Tikanga Māori, tēnei hiranga e tohu ana i te hua o ngā hononga ahurea ki ngā iwi taketake huri noa, kia whai hua mō Niu Tireni i ngā toronga ki whenua kē.

year: 2022