Response of Guanosine 5′-Triphosphate Concentration to Nutritional Changes and Its Significance for Bacillus subtilis Sporulation

We have investigated the changes in the guanosine 5'-triphosphate (GTP) and P-ribosyl-PP pools in stringent and relaxed strains of Bacillus subtilis under conditions frequently used to initiate sporulation. After a shift-down from a Casamino Acids-glutamate to a glutamate medium (Sterlini-Mandelstam shift-down), the pools of adenosine 5'-triphosphate and P-ribosyl-PP increased in both strains; in the stringent strain, ppGpp and pppGpp increased and GTP decreased rapidly, whereas in the relaxed strain, ppGpp and pppGpp increased only slightly and GTP decreased only slowly and less extensively. The stringent strain sporulated well, whereas the relaxed strain sporulated late and poorly. Addition of decoyinine, an inhibitor of guanosine 5'-monophosphate synthetase, caused a further decrease of GTP and initiated good sporulation of the relaxed strain. After a shift-down from a glucose-lactate to a lactate medium (Ramaley-Burden shift-down) the pool of P-ribosyl-PP (and GTP) decreased in both strains, indicating a shortage of purine precursors. This shift-down also caused a stringent response which prevented the consumption of nucleotides, as shown by the maintenance of adenosine 5'-triphosphate at a high concentration in the stringent strain but not in the relaxed strain. After a delay, the relaxed strain, in which GTP decreased as fast as in the stringent strain, sporulated also as efficiently. In nutrient sporulation medium the stringent strain and, less effectively, the relaxed strain accumulated ppGpp and pppGpp transiently towards the end of exponential growth. Eventually, the P-ribosyl-PP pool decreased drastically in both strains. In all cases the initiation of sporulation was correlated with a significant decrease of GTP. Granaticin, an antibiotic which prevents the charging of leucyl-transfer ribonucleic acid, was used to show that the stringent response inhibited the formation of xanthosine monophosphate from inosine monophosphate. It prevented the accumulation of xanthosine monophosphate in decoyinine-treated cultures of the stringent strain but not in those of the relaxed strain.     

alpha1-Antitrypsin variants in different racial groups in Malaysia.

In a study of Malaysians of different racial groups, 1,510 sera (908 from Malays, 371 from Chinese and 231 from Indians) were identified for their protease inhibitor (Pi) types. The gene frequencies for the alleles PiM, PiS and PiX in Malays were, respectively, 0.979, 0.015, and 0.007. In Chinese, the frequencies were 0.981, 0.019 and 0.000, and in Indians they were 0.976, 0.24, and 0.000. It is interesting that the usually rare PiX type is found in appreciable frequency in the Malays. Two different types with unusual behavior and obscure origin were also found.     

Partial trisomy 14q

Summary A dysmorphic female born with partial trisomy of the proximal segment of the long arm of chromosome 14 had 47 chromosomes. The extra one was acrocentric, smaller than the D group, and bigger than the G-chromosome group. By GTG banding it was identified as a deleted chromosome 14, the karyotype being 47,XX,+del 14(q24). Chromosome analysis of the parents was normal.     

An auto-anti-b in an a1b person. Serological studies.

The serum of a patient (Mr. Lat) with the regular blood group A1 B contains an anti-B reacting with all cells having a B antigen except Bx and cis AB. The anti-B reacts at 4 degrees C and occasionally at room temperature as shown by agglutination, absorption-eluction and by thermo-dynamic assays. The antibody is regarded as an irregular autoantibody belonging to the group of the so called "suppressed" or "latent" antibodies.     

Hepatocyte population dynamics during hydrocortisone and thioacetamide treatment

Summary The orderly organization in a number of discrete classes of weight persists in the hepatocytes during acute and chronic poisoning with thioacetamide and during a prolonged treatment with hydrocortisone, though many striking cytological and structural changes occur in the liver.The number of hepatocyte classes decreases under hydrocortisone treatment and during acute and chronic thioacetamide poisoning, and increases during recovery after acute thioacetamide poisoning and during the late phases of chronic thioacetamide poisoning. This is due to decrements and increments in dry mass of the hepatocytes, which occur by steps, through repeated losses and additions of a constant amount of solids substantially corresponding to the class period.Such a mechanism is similar to that acting in the hepatocyte atrophy due to starvation and in the hepatocyte enlargement occurring during postnatal development. Therefore, the increment and the decrement in dry mass by defined steps takes place in the hepatocytes in both physiological and pathological conditions.This work was supported by a grant of the Consiglio Nazionale delle Ricerche, Rome, Italy.     

Arabinogalactan proteins and arabinan pectins abound in the specialized matrices surrounding female gametes of the fern Ceratopteris richardii

Planta - Both male and female gametes of archegoniates are highly specialized cells surrounded by an extraprotoplasmic matrix rich in AGPs, which are speculated to facilitate development and gamete...     

NEMO specifically recognizes K63‐linked poly‐ubiquitin chains through a new bipartite ubiquitin‐binding domain

An important property of NEMO, the core element of the IKK complex involved in NF‐κB activation, resides in its ability to specifically recognize poly‐ubiquitin chains. A small domain called NOA/UBAN has been suggested to be responsible for this property. We recently demonstrated that the C‐terminal Zinc Finger (ZF) of NEMO is also able to bind ubiquitin. We show here by ZF swapping and mutagenesis that this represents its only function. While neither NOA nor ZF shows any preference for K63‐linked chains, we demonstrate that together they form a bipartite high‐affinity K63‐specific ubiquitin‐binding domain. A similar domain can be found in two other proteins, Optineurin and ABIN2, and can be freely exchanged with that of NEMO without interfering with its activity. This suggests that the main function of the C‐terminal half of NEMO is to specifically bind K63‐linked poly‐ubiquitin chains. We also demonstrate that the recently described binding of NEMO to linear poly‐ubiquitin chains is dependent on the NOA alone and does not require the presence of the ZF.