Gum microbes may be linked to allergies

The makeup of bacterial communities in gum tissue could be involved in allergic diseases in adults, according to NIEHS researchers and their collaborators.

The researchers analyzed sequencing data to characterize bacteria in gum tissue samples from 453 Norwegian adults. Their analysis included more than 2,200 types of bacteria. The results showed that oral bacterial communities that were less diverse were linked with atopy, a genetic tendency to develop allergic diseases, and rhinitis, which is irritation and inflammation of the mucous membrane inside the nose.

In addition, the relative abundance of different groups of bacteria was linked to atopy, rhinitis, and eczema — skin inflammation typically characterized by itchiness, redness, and a rash. The type of bacteria implicated in these conditions include Leptotrichia, Fusobacterium, and Streptococcus. Some bacteria were also related to the use of rhinitis medications. Additional findings showed that connections between microbial networks were linked to allergies. According to the authors, the results may lead to new treatments for allergic diseases. (JW)

Citation: Lee M, Vindenes HK, Fouladi F, Shigdel R, Ward JM, Peddada SD, London SJ, Bertelsen RJ. 2025. Oral microbiota related to allergy in Norwegian adults. J Allergy Clin Immunol Glob 4(2):100435.

Gene networks, external signals underly sex determination of germline

New findings at the single-nucleus level show how male and female germ cells develop in mouse embryos, according to NIEHS researchers and their collaborators.

During embryonic development, germ cells give rise to gametes, which are specialized reproductive cells. Gametes are essential for transmitting genetic information to the next generation. How primordial germ cells (PGCs) acquire their sex-specific fate (eggs or sperm) and respond to environmental signals in gonads that produce gametes remains unclear.

The researchers analyzed gene activity and chromatin — a complex interaction between DNA and protein — within individual nuclei of mouse PGCs during embryonic development. They identified molecules and chromatin regions involved in sex determination of germ cells. The results suggest that the accessibility of chromatin to molecular machinery that affects gene activity may influence the fate of PGCs.

In addition, single-nucleus sequencing data revealed transcription factors that control gene activity in PGCs. The findings also shed light on how PGCs communicate with other cells. According to the authors, many factors play a role in guiding PGC fate during embryonic development. The study could guide future research on reproductive diseases, such as infertility in humans. (JW)

Citation: Alexander AK, Rodriguez KF, Chen YY, Amato C, Estermann MA, Nicol B, Xu X, Yao HHC. 2025. Single-nucleus multiomics reveals the gene regulatory networks underlying sex determination of murine primordial germ cells. Elife 13:RP96591.

Short-term caloric restriction may affect sleep in healthy women

Reducing calorie intake may negatively affect sleep in healthy women without obesity, according to NIEHS researchers and their collaborators.

Short- and long-term calorie reduction has become increasingly popular due to their potential benefits for brain function, cancer prevention, heart health, and weight loss. Many people trying to lose weight rely on dieting, regardless of their body size. However, both energy balance from diet and quality sleep are essential for proper cellular function. Although sleep is also closely linked to the reproductive hormone system of girls and women, how hormonal changes across the menstrual cycle affect sleep remains poorly understood.

The researchers evaluated how short-term moderate calorie reduction influenced sleep throughout the menstrual cycle. They studied 17 healthy women, about 23 years old, who moderately reduced their calorie intake for five days during the early follicular phase of two menstrual cycles without a change in exercise. Participants wore devices to monitor sleep for the following month and provided urine and blood samples to measure reproductive and neurometabolic hormones. The researchers found a strong and consistent association between short-term dietary restriction and poorer sleep quality throughout the menstrual cycle.

The results add to the growing evidence that calorie restriction can affect sleep, particularly during hormonal fluctuations. According to the authors, future studies are needed to determine if these results apply to women with overweight or obesity, as well as how longer-term and more stringent caloric deficits impact sleep. (SS)

Citation: Kim AE, Shekhar S, Hirsch KR, Purse BP, McGrath JA, Zava TT, Smith-Ryan AE, Hall JE. 2025. Caloric restriction, the menstrual cycle and sleep in women without obesity. J Clin Endocrinol Metab; doi: 10.1210/clinem/dgaf145. [Online 5 March 2025].