Bacteriophage λ p gene shows host killing which is not dependent on λ DNA replication

Bacteriophage λ having a mutation replacing glycine by glutamic acid at the 48th codon of cro, kills the host under N- conditions; we call this the hk mutation. In λN-N-cl-hk phage-infected bacteria, the late gene R i expressed to a significant level, phage DNA synthesis occurs with better efficiency, and the Cro activity is around 20% less, all compared to those in λN-N-cl-hk+-infected bacteria. Segments of λ DNA from the left of pR to the right of tR2, carrying cro, cll, O,P, and the genes of the nin5 region from the above hk and hk+ phages, were cloned in pBR322. Studies with these plasmids and their derivatives having one or more of the λ genes deleted indicate that the hk mutation is lethal only when a functional P gene is also present. When expression of P from pR is elevated, due to the deletion of tR1, host killing also occurs without the hk mutation. We conclude that the higher levels of P protein, produced either (1) when cro has the hk mutation or (2) when tR1 is deleted, are lethal to the host. We also show that due to the hk mutation, the Cro protein becomes partially defective in its negative regulation at pR, resulting in the expression of P to a lethal level even in the absence of N protein-mediated antitermination. This P protein-induced host killing depends neither on λ DNA replication nor on any other gene functions of the phage

<span style="font-size: 21.5pt;mso-bidi-font-size:14.5pt;font-family:"Times New Roman","serif"">Clastogenic effects of dietary <i>supplement-Spirulina </i>alga, and some medicinal <span style="font-size:22.0pt;mso-bidi-font-size:15.0pt;font-family:"Times New Roman","serif"; mso-bidi-font-weight:bold">plant<b> </b><span style="font-size:21.5pt; mso-bidi-font-size:14.5pt;font-family:"Times New Roman","serif"">products from <i>Boswellia serrata, Withania smnnifera </i>on mice </span></span></span>

1068-1070<span style="font-size: 15.0pt;mso-bidi-font-size:8.0pt;font-family:" times="" new="" roman","serif""="">Pretreatment of aqueous extracts of Zyrulina <span style="font-size:15.5pt; mso-bidi-font-size:8.5pt;font-family:" times="" new="" roman","serif""="">(Spirulina), Aswagandha <span style="font-size:15.5pt;mso-bidi-font-size:8.5pt;font-family: " times="" new="" roman","serif""="">(Withania) <span style="font-size:15.0pt; mso-bidi-font-size:8.0pt;font-family:" times="" new="" roman","serif""="">and Nopane (Boswellia) <span style="font-size:15.0pt;mso-bidi-font-size:8.0pt;font-family: " times="" new="" roman","serif""="">on colchicine induced chromosome damage showed weakness of clastogenic activity in Swiss albino mice. None of the treatments increased significantly the number of chromosome aberrations. </span

Synthesis, structure, and electrochemistry of acetylide and oxo incorporated mixed Fe/Mo and Fe/W chalcogen-bridged clusters

Thermolysis of a benzene solution containing [Fe2Mo(CO)10(&#956;3-Se)2] (1) and [(&#951;5-C5Me5)W(CO)3C&#8801;CPh] (2) under an optimum concentration of oxygen in the reaction medium yields the cluster [(&#951;5-C5Me5)MoWFe2(O)(&#956;3-Se)(&#956;4-Se)(CO)8(CCPh)] (3), containing a monooxygenated metal center. Under an argon atmosphere, thermolysis of [Fe2Mo(CO)10(&#956;3-S)2] (4) with [(&#951;5-C5Me5)W(CO)3CCPh] (2) in benzene leads to an oxygen-free mixed metal cluster [(&#951;5-C5Me5)MoWFe4(&#956;3-S)3(&#956;4-S)(CO)14(CCPh)] (9). Interestingly, on reacting a benzene solution of 4 with 2 and [(&#951;5-C5Me5)Mo(CO)3C&#8801;CPh] (5) under an increased concentration of oxygen in the reaction medium gave way to clusters [(&#951;5-C5Me5)WMo2(&#956;-O)2(&#956;-S)(&#956;3-CCPh){Fe2(CO)6(&#956;3-S)2}2] (6), [(&#951;5-C5Me5)WMo(O)2(&#956;-O)(&#956;-CCPh){Fe2(CO)6(&#956;3-S)2}] (7), and [(&#951;5-C5Me5)Mo3(&#956;-O)2(&#956;-S)(&#956;3-CCPh){Fe2(CO)6(&#956;3-S)2}2] (8) with higher oxygen content. The structures of the newly formed clusters 3, 6, 7, 8, and 9 were established crystallographically and the oxo-containing Mo and W clusters investigated electrochemically

Insertion of CS<SUB>2</SUB> into a metal acetylide bond and conversion of the bonding mode of S<SUB>2</SUB>CC&#8801;CPh from &#951;<SUP>2</SUP> to &#951;<SUP>3</SUP>

Photolysis of a benzene solution containing [(L)Mo(CO)3(C&#8801;CPh)] (L=&#951;5-C5H5 1; &#951;5-C5Me5 2) and CS2 leads to the formation of dithiopropiolato containing complexes, [(L)Mo(CO)2(&#951;2-S2CC&#8801;CPh)] (L=&#951;5-C5H5 4; L=&#951;5-C5Me5 5). In presence of air, [(&#951;5-C5H5)Mo(CO)3(C&#8801;CPh)] reacts with CS2 to give 4 as the major and [(&#951;5-C5H5)Mo(O)(&#951;3-S2CC&#8801;CPh)] (6) as minor products. Similarly, [(&#951;5-C5Me5)Mo(CO)3(C&#8801;CPh)] reacts with CS2 under aerobic conditions to give compound 5 along with [(&#951;5-C5Me5)Mo(O)(&#951;3-S2CC&#8801;CPh)] (7) as minor product. When solutions of 4 or 5 are photolysed under a constant purge of air, 4 gives 6, and 5 gives 7 in high yields. Room temperature stirring of 5 with [W(CO)5(THF)] forms [&#951;5-C5Me5)Mo(CO)2CS2{W(CO)5}2C&#8801;CPh] (9). All new compounds have been characterised by IR and 1H-NMR spectroscopy and the structures of 4, 6, 7 and 9 have been established crystallographically

Synthesis, structure, and electrochemistry of [(&#951;<SUP>5</SUP>-C<SUB>5</SUB>H<SUB>5</SUB>)<SUB>2</SUB>Mo<SUB>2</SUB>WFe<SUB>2</SUB>(O)<SUB>2</SUB>(S)<SUB>2</SUB>(CO)<SUB>9</SUB>(CCPh)<SUB>2</SUB>]

Thermolysis of a toluene solution containing [Fe2W(CO)10(&#956; 3-S)2] (1) and [(&#951;5-C5H5)Mo(CO)3(CCPh)] (2) in the presence of air at 70 &#176;C yields the mixed-metal cluster [(&#951;5-C5H5)2Mo2WFe2(O)2(S)2(CO)9(CCPh)2] (3). The structure of 3 has been established crystallographically. It consists of a triangular Fe2W unit, each face of which is capped by a sulfido ligand. Each Fe atom bears three carbonyl groups, while the W atom is attached to two different Mo-containing moieties. It is &#960;-bonded to the C&#8801;C bond of a (&#951;5-C5H5)Mo(CO)3(C&#8801;CPh) unit, and it is also bonded to a second Mo atom, and this bond is bridged by an oxo group and a &#956;2,&#951;2-CCPh group. Also attached to this Mo atom is a terminal oxo group. Compound 3 has been investigated electrochemically